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Render onto s/s mesh
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Andrew Phillips
Aug 13, 2012, 6:34:13 PM8/13/12
to
Hello,
The pebbledash above my bay window (30s semi) had cracked extensively,
revealing a galvanised mesh that was now beyond rust.
So, I have knocked all the exterior render off the bay and now have
stainless steel expamet mesh ready to start the repair.
I understand that I should use stainless nails and tie wire with s/s
mesh, not galvanised.
That I should overlap sections of mesh by four inches.
That the mesh is backed by 1/4" thick wooden battens to allow the
render to penetrate the mesh and hang on.
That these battens are also to hold the bituminised felt sheet* behind
the mesh in place against the wooden studding behind it (I guess I
could use 1200 ga polythene sheet too).
*Thinking of 'undertile felt' from B&Q - similar thickness to the
original, though the B&Q stuff is lightly sanded.
Things I am less certain about - my house is from 1938 and has lime
plaster inside and lime mortar between the bricks, it's quite white in
appearance and the mesh had this in it too - but there appear to be
three coats of render, the inner one fairly white, the next a little
darker, the third with all the pebbles stuck in it. I am thing the
base coat is not pure lime mortar though? More likely 1:1:5
lime:cement:sharp sand? What about coarse sand - is that better?
I believe the layers should get weaker as you go out, so the next
layer might be 1:1:6?
Not sure about the pebbledash layer - needs to be able to take pebbles
though having tried this once they just seem to bounce off ;0)
Also not sure about 'bonding' to the mesh and/or the brickwork at the
edges with pva or 'sbr' slurry?
Is the initial 'pricking' coat to the mesh done in a special way or is
it just a thin coat to get the 'tongues' of render stuck through the
back?
Also not sure about putting waterproofer in the render - after all,
lime mortar is breathable, so is cement/lime mortar to a certain
extent. I don't want to trap water where a lime render could have
'breathed' it out so to speak.
Any comments/advice/tips??
Andy
The pebbledash above my bay window (30s semi) had cracked extensively,
revealing a galvanised mesh that was now beyond rust.
So, I have knocked all the exterior render off the bay and now have
stainless steel expamet mesh ready to start the repair.
I understand that I should use stainless nails and tie wire with s/s
mesh, not galvanised.
That I should overlap sections of mesh by four inches.
That the mesh is backed by 1/4" thick wooden battens to allow the
render to penetrate the mesh and hang on.
That these battens are also to hold the bituminised felt sheet* behind
the mesh in place against the wooden studding behind it (I guess I
could use 1200 ga polythene sheet too).
*Thinking of 'undertile felt' from B&Q - similar thickness to the
original, though the B&Q stuff is lightly sanded.
Things I am less certain about - my house is from 1938 and has lime
plaster inside and lime mortar between the bricks, it's quite white in
appearance and the mesh had this in it too - but there appear to be
three coats of render, the inner one fairly white, the next a little
darker, the third with all the pebbles stuck in it. I am thing the
base coat is not pure lime mortar though? More likely 1:1:5
lime:cement:sharp sand? What about coarse sand - is that better?
I believe the layers should get weaker as you go out, so the next
layer might be 1:1:6?
Not sure about the pebbledash layer - needs to be able to take pebbles
though having tried this once they just seem to bounce off ;0)
Also not sure about 'bonding' to the mesh and/or the brickwork at the
edges with pva or 'sbr' slurry?
Is the initial 'pricking' coat to the mesh done in a special way or is
it just a thin coat to get the 'tongues' of render stuck through the
back?
Also not sure about putting waterproofer in the render - after all,
lime mortar is breathable, so is cement/lime mortar to a certain
extent. I don't want to trap water where a lime render could have
'breathed' it out so to speak.
Any comments/advice/tips??
Andy
Phil L
Aug 13, 2012, 6:51:07 PM8/13/12
to
Andrew Phillips wrote:
> Hello,
> The pebbledash above my bay window (30s semi) had cracked extensively,
> revealing a galvanised mesh that was now beyond rust.
>
> So, I have knocked all the exterior render off the bay and now have
> stainless steel expamet mesh ready to start the repair.
>
If it's a square bay, I'd strongly advise you to clad it in upvc rather than
> Hello,
> The pebbledash above my bay window (30s semi) had cracked extensively,
> revealing a galvanised mesh that was now beyond rust.
>
> So, I have knocked all the exterior render off the bay and now have
> stainless steel expamet mesh ready to start the repair.
>
rendering, if it's rounded, IE curved, then render is the way forward.
> I understand that I should use stainless nails and tie wire with s/s
> mesh, not galvanised.
>
> That I should overlap sections of mesh by four inches.
> That the mesh is backed by 1/4" thick wooden battens to allow the
> render to penetrate the mesh and hang on.
>
used indoors - they won't last long outdooors, nor would I fancy trying to
affix them to mesh.
> That these battens are also to hold the bituminised felt sheet* behind
> the mesh in place against the wooden studding behind it (I guess I
> could use 1200 ga polythene sheet too).
>
> *Thinking of 'undertile felt' from B&Q - similar thickness to the
> original, though the B&Q stuff is lightly sanded.
>
> Things I am less certain about - my house is from 1938 and has lime
> plaster inside and lime mortar between the bricks, it's quite white in
> appearance and the mesh had this in it too - but there appear to be
> three coats of render, the inner one fairly white, the next a little
> darker, the third with all the pebbles stuck in it. I am thing the
> base coat is not pure lime mortar though? More likely 1:1:5
> lime:cement:sharp sand? What about coarse sand - is that better?
>
> I believe the layers should get weaker as you go out, so the next
> layer might be 1:1:6?
>
and pebbledashing.
You don't need three coats.
> Not sure about the pebbledash layer - needs to be able to take pebbles
> though having tried this once they just seem to bounce off ;0)
>
> Also not sure about 'bonding' to the mesh and/or the brickwork at the
> edges with pva or 'sbr' slurry?
>
> Is the initial 'pricking' coat to the mesh done in a special way or is
> it just a thin coat to get the 'tongues' of render stuck through the
> back?
>
wet and it will just sag through the mesh
> Also not sure about putting waterproofer in the render - after all,
> lime mortar is breathable, so is cement/lime mortar to a certain
> extent. I don't want to trap water where a lime render could have
> 'breathed' it out so to speak.
>
> Any comments/advice/tips??
(the 2nd coat won't stick to it when it's dry.)
Also, forget about the lime
Andy Dingley
Aug 13, 2012, 7:13:16 PM8/13/12
to
>> (30s semi)
> If it's a square bay, I'd strongly advise you to clad it in upvc rather than
> rendering,
Also if you'd like it to look fecking ugly afterwards and entirely
inappropriate for a '30s house.
You can round the UPVC "Shameless accident compensation cheque" effect
off nicely by finding a '30s semi with a semicircular arch porch, then
fitting a tiny UPVC door into the middle of it. Fill the gap with
more UPVC - you can get this in raised & fielded panels for a classy
effect.
> If it's a square bay, I'd strongly advise you to clad it in upvc rather than
> rendering,
inappropriate for a '30s house.
You can round the UPVC "Shameless accident compensation cheque" effect
off nicely by finding a '30s semi with a semicircular arch porch, then
fitting a tiny UPVC door into the middle of it. Fill the gap with
more UPVC - you can get this in raised & fielded panels for a classy
effect.
eeyore....@gmail.com
Aug 13, 2012, 7:21:05 PM8/13/12
to
On Monday, 13 August 2012 23:51:07 UTC+1, Phil L wrote:
> Andrew Phillips wrote:
>
> > Hello,
>
> > The pebbledash above my bay window (30s semi) had cracked extensively,
>
> > revealing a galvanised mesh that was now beyond rust.
>
> >
>
> > So, I have knocked all the exterior render off the bay and now have
>
> > stainless steel expamet mesh ready to start the repair.
>
> >
>
>
>
> If it's a square bay, I'd strongly advise you to clad it in upvc rather than
>
> rendering, if it's rounded, IE curved, then render is the way forward.
Sadly, I can't stand the sight of uPVC. Instant character bypass for a house
> Andrew Phillips wrote:
>
> > Hello,
>
> > The pebbledash above my bay window (30s semi) had cracked extensively,
>
> > revealing a galvanised mesh that was now beyond rust.
>
> >
>
> > So, I have knocked all the exterior render off the bay and now have
>
> > stainless steel expamet mesh ready to start the repair.
>
> >
>
>
>
> If it's a square bay, I'd strongly advise you to clad it in upvc rather than
>
> rendering, if it's rounded, IE curved, then render is the way forward.
;0) In any case, it's a single return bay and cladding that would look odd. If I were to go that way I'd do it in slate shingles, but I'd probably need planning permission to change the look of the house at the front like that plus it'd still look odd as a single return bay done in slate.
>
>
>
> > I understand that I should use stainless nails and tie wire with s/s
>
> > mesh, not galvanised.
>
> >
>
> yes
Tick.
>
>
> > I understand that I should use stainless nails and tie wire with s/s
>
> > mesh, not galvanised.
>
> >
>
> yes
>
>
>
> > That I should overlap sections of mesh by four inches.
>
> > That the mesh is backed by 1/4" thick wooden battens to allow the
>
> > render to penetrate the mesh and hang on.
>
> >
>
>
>
> You've lost me already, 1/4 of an inch batens? - these are lath, like what's
>
> used indoors - they won't last long outdooors, nor would I fancy trying to
>
> affix them to mesh.
The laths are as good as they day they were nailed in position 75 years ago - seriously, if I don't damage them taking them off, I'll use them again. They go behind the mesh - they (a) give a 1/4" gap for 'pricking out' of the mortar to occur through the mesh before the felt starts and (b) hold the bituminous felt dpm to the wooden studs behind.
>
>
> > That I should overlap sections of mesh by four inches.
>
> > That the mesh is backed by 1/4" thick wooden battens to allow the
>
> > render to penetrate the mesh and hang on.
>
> >
>
>
>
> You've lost me already, 1/4 of an inch batens? - these are lath, like what's
>
> used indoors - they won't last long outdooors, nor would I fancy trying to
>
> affix them to mesh.
>
>
>
> > That these battens are also to hold the bituminised felt sheet* behind
>
> > the mesh in place against the wooden studding behind it (I guess I
>
> > could use 1200 ga polythene sheet too).
>
> >
>
> Breathable membrane is what you require
Surely breathable membrane is not of much use if pressed hard up against the render coming through the mesh - it also looks too flimsy to have something touching it - since there is no airflow in the stud what is the point of breathable membrane? I would in effect be rendering onto breathable membrane, as the render will reach back through the mesh to it. If warm humid air could enter the stud from inside somehow then it might condense on the back of the cold render, but it can't so I don't see why brethable is necessary. The bituminous felt isn't breathable and the studwork behind is 100% sound.
>
>
> > That these battens are also to hold the bituminised felt sheet* behind
>
> > the mesh in place against the wooden studding behind it (I guess I
>
> > could use 1200 ga polythene sheet too).
>
> >
>
> Breathable membrane is what you require
>
>
>
> > *Thinking of 'undertile felt' from B&Q - similar thickness to the
>
> > original, though the B&Q stuff is lightly sanded.
>
> >
>
> > Things I am less certain about - my house is from 1938 and has lime
>
> > plaster inside and lime mortar between the bricks, it's quite white in
>
> > appearance and the mesh had this in it too - but there appear to be
>
> > three coats of render, the inner one fairly white, the next a little
>
> > darker, the third with all the pebbles stuck in it. I am thing the
>
> > base coat is not pure lime mortar though? More likely 1:1:5
>
> > lime:cement:sharp sand? What about coarse sand - is that better?
>
> >
>
> Red building sand, like what's used for mortar is what everyone renders with
>
>
>
> > I believe the layers should get weaker as you go out, so the next
>
> > layer might be 1:1:6?
>
> >
>
> I'd be temted to use 3:1 sand cement on first coat, then 4:1 for top coat
>
> and pebbledashing.
>
> You don't need three coats.
>
>
>
> > Not sure about the pebbledash layer - needs to be able to take pebbles
>
> > though having tried this once they just seem to bounce off ;0)
>
> >
>
> They stick better when wet.
Good idea
>
>
> > *Thinking of 'undertile felt' from B&Q - similar thickness to the
>
> > original, though the B&Q stuff is lightly sanded.
>
> >
>
> > Things I am less certain about - my house is from 1938 and has lime
>
> > plaster inside and lime mortar between the bricks, it's quite white in
>
> > appearance and the mesh had this in it too - but there appear to be
>
> > three coats of render, the inner one fairly white, the next a little
>
> > darker, the third with all the pebbles stuck in it. I am thing the
>
> > base coat is not pure lime mortar though? More likely 1:1:5
>
> > lime:cement:sharp sand? What about coarse sand - is that better?
>
> >
>
> Red building sand, like what's used for mortar is what everyone renders with
>
>
>
> > I believe the layers should get weaker as you go out, so the next
>
> > layer might be 1:1:6?
>
> >
>
> I'd be temted to use 3:1 sand cement on first coat, then 4:1 for top coat
>
> and pebbledashing.
>
> You don't need three coats.
>
>
>
> > Not sure about the pebbledash layer - needs to be able to take pebbles
>
> > though having tried this once they just seem to bounce off ;0)
>
> >
>
> They stick better when wet.
>
>
>
>
>
> > Also not sure about 'bonding' to the mesh and/or the brickwork at the
>
> > edges with pva or 'sbr' slurry?
>
> >
>
> not required on the mesh at all, but yes everywhere else
Excellent
>
>
>
>
> > Also not sure about 'bonding' to the mesh and/or the brickwork at the
>
> > edges with pva or 'sbr' slurry?
>
> >
>
> not required on the mesh at all, but yes everywhere else
>
>
>
> > Is the initial 'pricking' coat to the mesh done in a special way or is
>
> > it just a thin coat to get the 'tongues' of render stuck through the
>
> > back?
>
> >
>
> Just applied as normal, although it will need to be a fairly stiff mix, too
>
> wet and it will just sag through the mesh
Stiff mix, check.
>
>
> > Is the initial 'pricking' coat to the mesh done in a special way or is
>
> > it just a thin coat to get the 'tongues' of render stuck through the
>
> > back?
>
> >
>
> Just applied as normal, although it will need to be a fairly stiff mix, too
>
> wet and it will just sag through the mesh
>
>
>
> > Also not sure about putting waterproofer in the render - after all,
>
> > lime mortar is breathable, so is cement/lime mortar to a certain
>
> > extent. I don't want to trap water where a lime render could have
>
> > 'breathed' it out so to speak.
>
> >
>
> > Any comments/advice/tips??
>
>
>
> You can put W/P in the top coat but not the first
>
> (the 2nd coat won't stick to it when it's dry.)
Good point - needs suction I suppose as well as scratches. >
>
>
> > Also not sure about putting waterproofer in the render - after all,
>
> > lime mortar is breathable, so is cement/lime mortar to a certain
>
> > extent. I don't want to trap water where a lime render could have
>
> > 'breathed' it out so to speak.
>
> >
>
> > Any comments/advice/tips??
>
>
>
> You can put W/P in the top coat but not the first
>
> (the 2nd coat won't stick to it when it's dry.)
>
>
> Also, forget about the lime
You want me to mix a lime rendered house with a cement render? As I understand it, cement is very hard and can crack with older houses, plus if any moisture gets in through a crack it can't get out again - except inside. My brother had this problem with his house which had been inappropriately cement-rendered.
>
> Also, forget about the lime
Thing is, the original house render is fine after 75 years so I'm loathe to change it or mix and match - the only thing that failed was the galvanised mesh...
eeyore....@gmail.com
Aug 13, 2012, 7:48:28 PM8/13/12
to
On Tuesday, 14 August 2012 00:21:05 UTC+1, (unknown) wrote:
> On Monday, 13 August 2012 23:51:07 UTC+1, Phil L wrote:
>
> > Andrew Phillips wrote:
Regarding the studding behind the render etc - if it is ventilated I haven't seen how yet, but I only took a quick peek behind the bituminous felt dpm sheet. Since it is not ventilated from inside or outside, the only way it could be is via cavity wall air but again I'll have to have another look. The felt dpm by the way had a horizontal overlap join in it near the top - so does actually pass air, though as I say the air has nowhere to go as far as I've yet seen.
> On Monday, 13 August 2012 23:51:07 UTC+1, Phil L wrote:
>
> > Andrew Phillips wrote:
John Rumm
Aug 13, 2012, 8:14:55 PM8/13/12
to
On 13/08/2012 23:34, Andrew Phillips wrote:
> Hello,
> The pebbledash above my bay window (30s semi) had cracked extensively,
> revealing a galvanised mesh that was now beyond rust.
>
> So, I have knocked all the exterior render off the bay and now have
> stainless steel expamet mesh ready to start the repair.
>
> I understand that I should use stainless nails and tie wire with s/s
> mesh, not galvanised.
>
> That I should overlap sections of mesh by four inches.
> That the mesh is backed by 1/4" thick wooden battens to allow the
> render to penetrate the mesh and hang on.
I am guessing you are describing similar to what I did here:
> Hello,
> The pebbledash above my bay window (30s semi) had cracked extensively,
> revealing a galvanised mesh that was now beyond rust.
>
> So, I have knocked all the exterior render off the bay and now have
> stainless steel expamet mesh ready to start the repair.
>
> I understand that I should use stainless nails and tie wire with s/s
> mesh, not galvanised.
>
> That I should overlap sections of mesh by four inches.
> That the mesh is backed by 1/4" thick wooden battens to allow the
> render to penetrate the mesh and hang on.
http://www.internode.co.uk/loft/rendering.htm
> That these battens are also to hold the bituminised felt sheet* behind
> the mesh in place against the wooden studding behind it (I guess I
> could use 1200 ga polythene sheet too).
> *Thinking of 'undertile felt' from B&Q - similar thickness to the
> original, though the B&Q stuff is lightly sanded.
> Things I am less certain about - my house is from 1938 and has lime
> plaster inside and lime mortar between the bricks, it's quite white in
> appearance and the mesh had this in it too - but there appear to be
> three coats of render, the inner one fairly white, the next a little
> darker, the third with all the pebbles stuck in it. I am thing the
> base coat is not pure lime mortar though? More likely 1:1:5
> lime:cement:sharp sand? What about coarse sand - is that better?
these situations acts as a plasticiser, but does not bestow the
traditional attributes of "proper" lime mortar.
> I believe the layers should get weaker as you go out, so the next
> layer might be 1:1:6?
substrate though.
> Not sure about the pebbledash layer - needs to be able to take pebbles
> though having tried this once they just seem to bounce off ;0)
though.
> Also not sure about 'bonding' to the mesh and/or the brickwork at the
> edges with pva or 'sbr' slurry?
edges. Keeps it all tidy an in place.
> Is the initial 'pricking' coat to the mesh done in a special way or is
> it just a thin coat to get the 'tongues' of render stuck through the
> back?
mesh. Scratch it up, and then stick the finish coat on that.
> Also not sure about putting waterproofer in the render - after all,
> lime mortar is breathable, so is cement/lime mortar to a certain
> extent. I don't want to trap water where a lime render could have
> 'breathed' it out so to speak.
they solve.
--
Cheers,
John.
/=================================================================\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\=================================================================/
eeyore....@gmail.com
Aug 13, 2012, 9:00:42 PM8/13/12
to
On Tuesday, August 14, 2012 1:14:55 AM UTC+1, John Rumm wrote:
> On 13/08/2012 23:34, Andrew Phillips wrote:
>
>
>
> > Hello,
>
> > The pebbledash above my bay window (30s semi) had cracked extensively,
>
> > revealing a galvanised mesh that was now beyond rust.
>
> >
>
> > So, I have knocked all the exterior render off the bay and now have
>
> > stainless steel expamet mesh ready to start the repair.
>
> >
>
> > I understand that I should use stainless nails and tie wire with s/s
>
> > mesh, not galvanised.
>
> >
>
> > That I should overlap sections of mesh by four inches.
>
> > That the mesh is backed by 1/4" thick wooden battens to allow the
>
> > render to penetrate the mesh and hang on.
>
>
>
> I am guessing you are describing similar to what I did here:
Hello John,
> On 13/08/2012 23:34, Andrew Phillips wrote:
>
>
>
> > Hello,
>
> > The pebbledash above my bay window (30s semi) had cracked extensively,
>
> > revealing a galvanised mesh that was now beyond rust.
>
> >
>
> > So, I have knocked all the exterior render off the bay and now have
>
> > stainless steel expamet mesh ready to start the repair.
>
> >
>
> > I understand that I should use stainless nails and tie wire with s/s
>
> > mesh, not galvanised.
>
> >
>
> > That I should overlap sections of mesh by four inches.
>
> > That the mesh is backed by 1/4" thick wooden battens to allow the
>
> > render to penetrate the mesh and hang on.
>
>
>
> I am guessing you are describing similar to what I did here:
Yes, That's exactly what I'm doing!
>
>
>
> http://www.internode.co.uk/loft/rendering.htm
>
>
>
> > That these battens are also to hold the bituminised felt sheet* behind
>
> > the mesh in place against the wooden studding behind it (I guess I
>
> > could use 1200 ga polythene sheet too).
>
>
>
> Or building paper is a another common backing...
I've heard of it, will look it up - sounds...fragile.
>
>
> http://www.internode.co.uk/loft/rendering.htm
>
>
>
> > That these battens are also to hold the bituminised felt sheet* behind
>
> > the mesh in place against the wooden studding behind it (I guess I
>
> > could use 1200 ga polythene sheet too).
>
>
>
> Or building paper is a another common backing...
>
>
>
> > *Thinking of 'undertile felt' from B&Q - similar thickness to the
>
> > original, though the B&Q stuff is lightly sanded.
>
>
>
> Yup, something with some Hessian reinforcement is easier to fix.
Mine is held onto the studding by laths and clout nails and onto the brickwork at the edges by clout nails into wooden rawlplugs and with penny sized copper washers.
>
>
> > *Thinking of 'undertile felt' from B&Q - similar thickness to the
>
> > original, though the B&Q stuff is lightly sanded.
>
>
>
> Yup, something with some Hessian reinforcement is easier to fix.
>
>
>
> > Things I am less certain about - my house is from 1938 and has lime
>
> > plaster inside and lime mortar between the bricks, it's quite white in
>
> > appearance and the mesh had this in it too - but there appear to be
>
> > three coats of render, the inner one fairly white, the next a little
>
> > darker, the third with all the pebbles stuck in it. I am thing the
>
> > base coat is not pure lime mortar though? More likely 1:1:5
>
> > lime:cement:sharp sand? What about coarse sand - is that better?
>
>
>
> If you use cement in it, then its not really lime render. The lime in
>
> these situations acts as a plasticiser, but does not bestow the
>
> traditional attributes of "proper" lime mortar.
I understand that, although I do believe it is somewhat breathable compared to solely cement mortar - the cement fills up the inter-grain spaces pretty much completely I believe.
>
>
> > Things I am less certain about - my house is from 1938 and has lime
>
> > plaster inside and lime mortar between the bricks, it's quite white in
>
> > appearance and the mesh had this in it too - but there appear to be
>
> > three coats of render, the inner one fairly white, the next a little
>
> > darker, the third with all the pebbles stuck in it. I am thing the
>
> > base coat is not pure lime mortar though? More likely 1:1:5
>
> > lime:cement:sharp sand? What about coarse sand - is that better?
>
>
>
> If you use cement in it, then its not really lime render. The lime in
>
> these situations acts as a plasticiser, but does not bestow the
>
> traditional attributes of "proper" lime mortar.
My problem is that I can't tell if the original builder used lime mortar or cement/lime mortar. The sand where I am is silver and when you add lime it's snowy white. That's the colour the base coat is, snowy white. The next coat is a shade darker, but that could just be a weaker mix so more sane. I guess it's hard to tell what mortar is made of...
>
>
>
> > I believe the layers should get weaker as you go out, so the next
>
> > layer might be 1:1:6?
>
>
>
> Not sure its that critical. You don't want the render stronger than the
>
> substrate though.
The substrate is mesh and those common bricks that are too ugly to use without a coating.
>
>
> > I believe the layers should get weaker as you go out, so the next
>
> > layer might be 1:1:6?
>
>
>
> Not sure its that critical. You don't want the render stronger than the
>
> substrate though.
>
>
>
> > Not sure about the pebbledash layer - needs to be able to take pebbles
>
> > though having tried this once they just seem to bounce off ;0)
>
>
>
> Never tried it, so can't comment... there are some videos on youtube
>
> though.
>
>
>
> > Also not sure about 'bonding' to the mesh and/or the brickwork at the
>
> > edges with pva or 'sbr' slurry?
>
>
>
> Use corner beads at the corners (fixed first), and a render stop at any
>
> edges. Keeps it all tidy an in place.
The render stop at the bottom - the bell-casting - must have been a piece of wood, removed after the render set. The render also sits partly on a beam above the window below. The beam has the outside edge sloping so as to offer the render some support where it touches it. There is a little rot in the centre where the render sat on it but the beam is otherwise sound. I will cut the rot out and splice in a small facing strip profiled to blend in, with nails and Cascamite boat glue, plus treat the wood.
>
>
> > Not sure about the pebbledash layer - needs to be able to take pebbles
>
> > though having tried this once they just seem to bounce off ;0)
>
>
>
> Never tried it, so can't comment... there are some videos on youtube
>
> though.
>
>
>
> > Also not sure about 'bonding' to the mesh and/or the brickwork at the
>
> > edges with pva or 'sbr' slurry?
>
>
>
> Use corner beads at the corners (fixed first), and a render stop at any
>
> edges. Keeps it all tidy an in place.
There is no corner bead that I could see - the mesh just went around the corner. There are extra laths in the corner to support the mesh at it turns 90 degrees.
>
>
>
> > Is the initial 'pricking' coat to the mesh done in a special way or is
>
> > it just a thin coat to get the 'tongues' of render stuck through the
>
> > back?
>
>
>
> I just apply normal thickness backing coat, which pretty much hides the
>
> mesh. Scratch it up, and then stick the finish coat on that.
>
>
>
> > Also not sure about putting waterproofer in the render - after all,
>
> > lime mortar is breathable, so is cement/lime mortar to a certain
>
> > extent. I don't want to trap water where a lime render could have
>
> > 'breathed' it out so to speak.
>
>
>
> Don't think I would. Impermeable coatings can cause as many problems as
>
> they solve.
Yes, I have seen this with my own eyes in other places. It is a concern, this render mix/waterproofer business, as the success of this type of construction might depend on the use of breathable lime - I don't know enough about it either way to make my mind up. Like I said, everything in the house contains lime, the brickwork mortar, the render, the interior lime plaster. The only unknown is if it's got any cement in it at all...
>
>
> > Is the initial 'pricking' coat to the mesh done in a special way or is
>
> > it just a thin coat to get the 'tongues' of render stuck through the
>
> > back?
>
>
>
> I just apply normal thickness backing coat, which pretty much hides the
>
> mesh. Scratch it up, and then stick the finish coat on that.
>
>
>
> > Also not sure about putting waterproofer in the render - after all,
>
> > lime mortar is breathable, so is cement/lime mortar to a certain
>
> > extent. I don't want to trap water where a lime render could have
>
> > 'breathed' it out so to speak.
>
>
>
> Don't think I would. Impermeable coatings can cause as many problems as
>
> they solve.
NT
Aug 14, 2012, 3:52:59 AM8/14/12
to
builds in a failure point, since its galv, and its perfect
straightness doesn't always suit old houses. I'd be inclined to leave
it out and form your edges by hand.
I would defintely not use plain cement render for the base layer when
you can use an insulating render such as papercrete, or standard
render with expanded stone included.
Vapour barrier should go on the warm side of any insulation, otherwise
condensation and rot is likely.
Pure white render is pretty well bound to be lime. Lime mortar is
normally 3:1 to 2.5:1, and isnt generally varied the way cement mixes
are. Lime is much softer, takes ages to set, and needs to be trowelled
during setting as it cracks. Unlike cement, trowelling when it part
set doesn't harm it.
Finally mixing a very little plastic fibre into the 1st coat can
reduce the risk of cracking to a degree. You can buy it at daft
prices, or just cut synthetic carpet and rag into diagonal strips and
feed it through a shredder.
NT
John Rumm
Aug 14, 2012, 9:29:01 AM8/14/12
to
On 14/08/2012 02:00, eeyore....@gmail.com wrote:
> On Tuesday, August 14, 2012 1:14:55 AM UTC+1, John Rumm wrote:
>> I am guessing you are describing similar to what I did here:
>
> Hello John,
>
> Yes, That's exactly what I'm doing!
>> http://www.internode.co.uk/loft/rendering.htm
> On Tuesday, August 14, 2012 1:14:55 AM UTC+1, John Rumm wrote:
>> I am guessing you are describing similar to what I did here:
>
> Hello John,
>
> Yes, That's exactly what I'm doing!
>> http://www.internode.co.uk/loft/rendering.htm
>> Or building paper is a another common backing...
>
> I've heard of it, will look it up - sounds...fragile.
Ultimately the strength comes from the rendered metal lath - all you
>
> I've heard of it, will look it up - sounds...fragile.
really need is something to stop it falling through as you render.
>>> *Thinking of 'undertile felt' from B&Q - similar thickness to
>>> the
>>
>>> original, though the B&Q stuff is lightly sanded.
>>
>>
>>
>> Yup, something with some Hessian reinforcement is easier to fix.
>
> Mine is held onto the studding by laths and clout nails and onto the
> brickwork at the edges by clout nails into wooden rawlplugs and with
> penny sized copper washers.
clenching them over was another common way (gives a length of grip along
the nail rather than just the head)
>> If you use cement in it, then its not really lime render. The lime
>> in
>> these situations acts as a plasticiser, but does not bestow the
>> traditional attributes of "proper" lime mortar.
>
> I understand that, although I do believe it is somewhat breathable
> compared to solely cement mortar - the cement fills up the
> inter-grain spaces pretty much completely I believe.
>
> My problem is that I can't tell if the original builder used lime
> mortar or cement/lime mortar. The sand where I am is silver and when
> you add lime it's snowy white. That's the colour the base coat is,
> snowy white. The next coat is a shade darker, but that could just be
> a weaker mix so more sane. I guess it's hard to tell what mortar is
> made of...
>> Use corner beads at the corners (fixed first), and a render stop at
>> any
>>
>> edges. Keeps it all tidy an in place.
>
> The render stop at the bottom - the bell-casting - must have been a
> piece of wood, removed after the render set. The render also sits
Yup, quite common. Also common to staple a bit of sash cord along the
>> any
>>
>> edges. Keeps it all tidy an in place.
>
> The render stop at the bottom - the bell-casting - must have been a
> piece of wood, removed after the render set. The render also sits
wood before putting in place. That then casts a "drip" into the bottom
of the render so the water falls away from the wall rather than run down
it.
> partly on a beam above the window below. The beam has the outside
> edge sloping so as to offer the render some support where it touches
> it. There is a little rot in the centre where the render sat on it
> but the beam is otherwise sound. I will cut the rot out and splice in
> a small facing strip profiled to blend in, with nails and Cascamite
> boat glue, plus treat the wood.
>
> There is no corner bead that I could see - the mesh just went around
> the corner. There are extra laths in the corner to support the mesh
> at it turns 90 degrees.
>> Don't think I would. Impermeable coatings can cause as many
>> problems as
>>
>> they solve.
>
> Yes, I have seen this with my own eyes in other places. It is a
> concern, this render mix/waterproofer business, as the success of
> this type of construction might depend on the use of breathable lime
> - I don't know enough about it either way to make my mind up. Like I
> said, everything in the house contains lime, the brickwork mortar,
> the render, the interior lime plaster. The only unknown is if it's
> got any cement in it at all...
ventilation somewhere if you need it.
Andrew Gabriel
Aug 14, 2012, 10:18:01 AM8/14/12
to
In article <hNOdncbVL6IIz7fN...@brightview.co.uk>,
The problem I had was forcing the render through the lath at all.
It tends to just push the lath against the wall behind, but not
go through and stick to the wall itself, and springs away when
you stop applying the pressure. I was only doing a very small area,
but I was very close to taking the lath off, rendering a very thin
layer direct to the wall, and then putting the lath back in the top
of that layer before continuing.
BTW, handling a sheet of expanded stainless steel lath is not very
dissimilar from handling a coil of razor wire - very difficult to
avoid cutting yourself to shreds. I might even suggest wearing
goggles.
--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]
John Rumm <see.my.s...@nowhere.null> writes:
> On 14/08/2012 02:00, eeyore....@gmail.com wrote:
>> On Tuesday, August 14, 2012 1:14:55 AM UTC+1, John Rumm wrote:
>
>>> I am guessing you are describing similar to what I did here:
>>
>> Hello John,
>>
>> Yes, That's exactly what I'm doing!
>
>>> http://www.internode.co.uk/loft/rendering.htm
>
>>> Or building paper is a another common backing...
>>
>> I've heard of it, will look it up - sounds...fragile.
>
> Ultimately the strength comes from the rendered metal lath - all you
> really need is something to stop it falling through as you render.
I've only rendered onto expanded stainless steel lath once.
> On 14/08/2012 02:00, eeyore....@gmail.com wrote:
>> On Tuesday, August 14, 2012 1:14:55 AM UTC+1, John Rumm wrote:
>
>>> I am guessing you are describing similar to what I did here:
>>
>> Hello John,
>>
>> Yes, That's exactly what I'm doing!
>
>>> http://www.internode.co.uk/loft/rendering.htm
>
>>> Or building paper is a another common backing...
>>
>> I've heard of it, will look it up - sounds...fragile.
>
> Ultimately the strength comes from the rendered metal lath - all you
> really need is something to stop it falling through as you render.
The problem I had was forcing the render through the lath at all.
It tends to just push the lath against the wall behind, but not
go through and stick to the wall itself, and springs away when
you stop applying the pressure. I was only doing a very small area,
but I was very close to taking the lath off, rendering a very thin
layer direct to the wall, and then putting the lath back in the top
of that layer before continuing.
BTW, handling a sheet of expanded stainless steel lath is not very
dissimilar from handling a coil of razor wire - very difficult to
avoid cutting yourself to shreds. I might even suggest wearing
goggles.
--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]
John Rumm
Aug 14, 2012, 10:48:33 AM8/14/12
to
On 14/08/2012 15:18, Andrew Gabriel wrote:
> In article <hNOdncbVL6IIz7fN...@brightview.co.uk>,
> John Rumm <see.my.s...@nowhere.null> writes:
>> On 14/08/2012 02:00, eeyore....@gmail.com wrote:
>>> On Tuesday, August 14, 2012 1:14:55 AM UTC+1, John Rumm wrote:
>>
>>>> I am guessing you are describing similar to what I did here:
>>>
>>> Hello John,
>>>
>>> Yes, That's exactly what I'm doing!
>>
>>>> http://www.internode.co.uk/loft/rendering.htm
>>
>>>> Or building paper is a another common backing...
>>>
>>> I've heard of it, will look it up - sounds...fragile.
>>
>> Ultimately the strength comes from the rendered metal lath - all you
Sorry - meant to say the lath and the render there!
> In article <hNOdncbVL6IIz7fN...@brightview.co.uk>,
> John Rumm <see.my.s...@nowhere.null> writes:
>> On 14/08/2012 02:00, eeyore....@gmail.com wrote:
>>> On Tuesday, August 14, 2012 1:14:55 AM UTC+1, John Rumm wrote:
>>
>>>> I am guessing you are describing similar to what I did here:
>>>
>>> Hello John,
>>>
>>> Yes, That's exactly what I'm doing!
>>
>>>> http://www.internode.co.uk/loft/rendering.htm
>>
>>>> Or building paper is a another common backing...
>>>
>>> I've heard of it, will look it up - sounds...fragile.
>>
>> Ultimately the strength comes from the rendered metal lath - all you
>> really need is something to stop it falling through as you render.
>
> I've only rendered onto expanded stainless steel lath once.
> The problem I had was forcing the render through the lath at all.
> It tends to just push the lath against the wall behind, but not
> go through and stick to the wall itself, and springs away when
> you stop applying the pressure. I was only doing a very small area,
> but I was very close to taking the lath off, rendering a very thin
> layer direct to the wall, and then putting the lath back in the top
> of that layer before continuing.
through easy enough. You get better integration of the lath if there is
a bit of space behind it every now and then.
> BTW, handling a sheet of expanded stainless steel lath is not very
> dissimilar from handling a coil of razor wire - very difficult to
> avoid cutting yourself to shreds. I might even suggest wearing
> goggles.
quite hazardous. Stiff gloves and a small disc in an 115mm AG to cut.
The Natural Philosopher
Aug 14, 2012, 11:28:27 AM8/14/12
to
Andrew Gabriel wrote:
> In article <hNOdncbVL6IIz7fN...@brightview.co.uk>,
> John Rumm <see.my.s...@nowhere.null> writes:
>> On 14/08/2012 02:00, eeyore....@gmail.com wrote:
>>> On Tuesday, August 14, 2012 1:14:55 AM UTC+1, John Rumm wrote:
>>>> I am guessing you are describing similar to what I did here:
>>> Hello John,
>>>
>>> Yes, That's exactly what I'm doing!
>>>> http://www.internode.co.uk/loft/rendering.htm
>>>> Or building paper is a another common backing...
>>> I've heard of it, will look it up - sounds...fragile.
>> Ultimately the strength comes from the rendered metal lath - all you
>> really need is something to stop it falling through as you render.
>
> I've only rendered onto expanded stainless steel lath once.
> The problem I had was forcing the render through the lath at all.
> It tends to just push the lath against the wall behind, but not
> go through and stick to the wall itself, and springs away when
> you stop applying the pressure. I was only doing a very small area,
> but I was very close to taking the lath off, rendering a very thin
> layer direct to the wall, and then putting the lath back in the top
> of that layer before continuing.
>
When the guys did here, (wood frame) they ply-ed the whole exterior,
> In article <hNOdncbVL6IIz7fN...@brightview.co.uk>,
> John Rumm <see.my.s...@nowhere.null> writes:
>> On 14/08/2012 02:00, eeyore....@gmail.com wrote:
>>> On Tuesday, August 14, 2012 1:14:55 AM UTC+1, John Rumm wrote:
>>>> I am guessing you are describing similar to what I did here:
>>> Hello John,
>>>
>>> Yes, That's exactly what I'm doing!
>>>> http://www.internode.co.uk/loft/rendering.htm
>>>> Or building paper is a another common backing...
>>> I've heard of it, will look it up - sounds...fragile.
>> Ultimately the strength comes from the rendered metal lath - all you
>> really need is something to stop it falling through as you render.
>
> I've only rendered onto expanded stainless steel lath once.
> The problem I had was forcing the render through the lath at all.
> It tends to just push the lath against the wall behind, but not
> go through and stick to the wall itself, and springs away when
> you stop applying the pressure. I was only doing a very small area,
> but I was very close to taking the lath off, rendering a very thin
> layer direct to the wall, and then putting the lath back in the top
> of that layer before continuing.
>
shoved a semi-permeable membrane over that and then nailed *vertical
battens* to that and the metal lath over that, with a drip bead at the
bottom.
That meant the render keyed very well and there was an air gap between
the render and the wood, which allows it to dry out if there is any
penetration, and also allows the walls to breath a little.
> BTW, handling a sheet of expanded stainless steel lath is not very
> dissimilar from handling a coil of razor wire - very difficult to
> avoid cutting yourself to shreds. I might even suggest wearing
> goggles.
>
--
Ineptocracy
(in-ep-toc’-ra-cy) – a system of government where the least capable to
lead are elected by the least capable of producing, and where the
members of society least likely to sustain themselves or succeed, are
rewarded with goods and services paid for by the confiscated wealth of a
diminishing number of producers.
eeyore....@gmail.com
Aug 14, 2012, 2:48:48 PM8/14/12
to
On Tuesday, 14 August 2012 15:18:01 UTC+1, Andrew Gabriel wrote:
> In article <hNOdncbVL6IIz7fN...@brightview.co.uk>,
>
> John Rumm <see.my.s...@nowhere.null> writes:
>
> In article <hNOdncbVL6IIz7fN...@brightview.co.uk>,
>
> John Rumm <see.my.s...@nowhere.null> writes:
>
> > On 14/08/2012 02:00, eeyore wrote:
>
> >> On Tuesday, August 14, 2012 1:14:55 AM UTC+1, John Rumm wrote:
>
> >
>
> >>> I am guessing you are describing similar to what I did here:
>
> >>
>
> >> Hello John,
>
> >>
>
> >> Yes, That's exactly what I'm doing!
>
> >
>
> >>> http://www.internode.co.uk/loft/rendering.htm
>
> >
>
> >>> Or building paper is a another common backing...
>
> >>
>
> >> I've heard of it, will look it up - sounds...fragile.
>
> >
>
> > Ultimately the strength comes from the rendered metal lath - all you
>
> > really need is something to stop it falling through as you render.
>
>
>
> I've only rendered onto expanded stainless steel lath once.
>
> The problem I had was forcing the render through the lath at all.
>
> It tends to just push the lath against the wall behind, but not
>
> go through and stick to the wall itself, and springs away when
>
> you stop applying the pressure. I was only doing a very small area,
>
> but I was very close to taking the lath off, rendering a very thin
>
> layer direct to the wall, and then putting the lath back in the top
>
> of that layer before continuing.
>
>
>
> BTW, handling a sheet of expanded stainless steel lath is not very
>
> dissimilar from handling a coil of razor wire - very difficult to
>
> avoid cutting yourself to shreds. I might even suggest wearing
>
> goggles.
I have already found out what 'orrible stuff s/s mesh is - it was hard enough trying to get it to roll up to get it into the car! I read that it is best to angle the holding nails for it so as to tension the sheet. Best to start in the middle and work out apparently. I expect I'll preform it if I need to take it around the corner to the return leg of the bay.
>
> >> On Tuesday, August 14, 2012 1:14:55 AM UTC+1, John Rumm wrote:
>
> >
>
> >>> I am guessing you are describing similar to what I did here:
>
> >>
>
> >> Hello John,
>
> >>
>
> >> Yes, That's exactly what I'm doing!
>
> >
>
> >>> http://www.internode.co.uk/loft/rendering.htm
>
> >
>
> >>> Or building paper is a another common backing...
>
> >>
>
> >> I've heard of it, will look it up - sounds...fragile.
>
> >
>
> > Ultimately the strength comes from the rendered metal lath - all you
>
> > really need is something to stop it falling through as you render.
>
>
>
> I've only rendered onto expanded stainless steel lath once.
>
> The problem I had was forcing the render through the lath at all.
>
> It tends to just push the lath against the wall behind, but not
>
> go through and stick to the wall itself, and springs away when
>
> you stop applying the pressure. I was only doing a very small area,
>
> but I was very close to taking the lath off, rendering a very thin
>
> layer direct to the wall, and then putting the lath back in the top
>
> of that layer before continuing.
>
>
>
> BTW, handling a sheet of expanded stainless steel lath is not very
>
> dissimilar from handling a coil of razor wire - very difficult to
>
> avoid cutting yourself to shreds. I might even suggest wearing
>
> goggles.
Regarding lime mortar, I read somewhere that lime fizzes when exposed to brick acid, whereas ordinary portland cement just bubbles gently. This might be an interesting test to try on what render I've already hacked off - though I have battery (sulphuric) acid available, not 'brick acid' whatever that is. I presume the lime will react and dissolve/turn to gas whilst the sand will be relatively unaffected. I'll give it a try with a few bits of mortar of different types of known provenance.
I'm veering back towards straight lime:sand render now, of the 1:2.5 variety for the base coat, but need to research it more as I know lime washes away in rain eventually ( I lime washed a wall once and after a couple of years it started to wear thin) so what's to stop a pebble-dash bearing final coat from eroding? Plus, people advise you should make up lime putty/coarse stuff weeks before you use it which is a pain, though I think I have at least two weeks before I'm ready to start rendering....
It still seems to me I haven't quite figured out what the original builders used as a render mix for all the layers, though lime was part of it.>
John Rumm
Aug 14, 2012, 4:33:41 PM8/14/12
to
On 14/08/2012 19:48, eeyore....@gmail.com wrote:
> Regarding lime mortar, I read somewhere that lime fizzes when exposed
> to brick acid, whereas ordinary portland cement just bubbles gently.
> This might be an interesting test to try on what render I've already
> hacked off - though I have battery (sulphuric) acid available, not
> 'brick acid' whatever that is.
Brick acid is HCL, not H2S04
> Regarding lime mortar, I read somewhere that lime fizzes when exposed
> to brick acid, whereas ordinary portland cement just bubbles gently.
> This might be an interesting test to try on what render I've already
> hacked off - though I have battery (sulphuric) acid available, not
> 'brick acid' whatever that is.
(can fizz on cement as well)
NT
Aug 14, 2012, 7:54:09 PM8/14/12
to
On Aug 14, 7:48 pm, eeyore.is.h...@gmail.com wrote:
> On Tuesday, 14 August 2012 15:18:01 UTC+1, Andrew Gabriel wrote:
> > In article <hNOdncbVL6IIz7fNnZ2dnUVZ8gudn...@brightview.co.uk>,
> On Tuesday, 14 August 2012 15:18:01 UTC+1, Andrew Gabriel wrote:
strength might - cement is far harder. But really, why would anyone
pay extra for white cement? If its white, its lime.
> already hacked off - though I have battery (sulphuric) acid available, not 'brick acid' whatever that is. I presume the lime will react and
> dissolve/turn to gas whilst the sand will be relatively unaffected. I'll give it a try with a few bits of mortar of different types of known provenance.
>
> I'm veering back towards straight lime:sand render now, of the 1:2.5 variety for the base coat, but need to research it more as I know lime washes away in rain eventually ( I lime washed a wall once and after a couple of years it started to wear thin) so what's to stop a pebble-dash bearing final coat from eroding? Plus, people advise you should make
what you had. Also lime does initially if it sees much rain before its
set, so check the forecast for the 2 days ahead.
> up lime putty/coarse stuff weeks before you use it which is a pain, though I think I have at least two weeks before I'm ready to start rendering....
> It still seems to me I haven't quite figured out what the original builders used as a render mix for all the layers, though lime was part of it.>
NT
Aug 15, 2012, 9:00:50 AM8/15/12
to
trowel at a fairly strong angle, so just the edge inch or so pushes
the mix through
NT
Martin Bonner
Aug 15, 2012, 10:52:52 AM8/15/12
to
On Tuesday, 14 August 2012 01:14:55 UTC+1, John Rumm wrote:
> > Things I am less certain about - my house is from 1938 and has lime
> > plaster inside and lime mortar between the bricks,
> > I am thinking the
> > Things I am less certain about - my house is from 1938 and has lime
> > plaster inside and lime mortar between the bricks,
> > base coat is not pure lime mortar though? More likely 1:1:5
> > lime:cement:sharp sand? What about coarse sand - is that better?
>
> If you use cement in it, then its not really lime render. The lime in
> these situations acts as a plasticiser, but does not bestow the
> traditional attributes of "proper" lime mortar.
<nods> I'd go for a hydraulic lime render. Hydraulic lime comes in bags like cement, and sets like cement - but the result isn't as stiff, and is breathable.
> > lime:cement:sharp sand? What about coarse sand - is that better?
>
> If you use cement in it, then its not really lime render. The lime in
> these situations acts as a plasticiser, but does not bestow the
> traditional attributes of "proper" lime mortar.
djam...@sky.com
Aug 7, 2015, 8:07:43 PM8/7/15
to
Andrew Gabriel
Aug 8, 2015, 4:19:14 AM8/8/15
to
In article <46cc9891-3138-4ca9...@googlegroups.com>,
Is this on the inside or the outside?
If you are pulling it off anyway, now is the time to make sure
it's well insulated behind it.
djam...@sky.com writes:
> Need some info on rendering a round bay window.All the rendering had blown and cracked just on the round bay,so i removed all the loose,then found a like a corrugated plastic sheet with bitumen on it,and felt behind it.Their isnt many supports ie timber behind the sheet,so could this be reason why it had blown ?If i added more timber supports and made it more secure,would this cure it ?
It doesn't sound like a product suitable for rendering on.
> Need some info on rendering a round bay window.All the rendering had blown and cracked just on the round bay,so i removed all the loose,then found a like a corrugated plastic sheet with bitumen on it,and felt behind it.Their isnt many supports ie timber behind the sheet,so could this be reason why it had blown ?If i added more timber supports and made it more secure,would this cure it ?
Is this on the inside or the outside?
If you are pulling it off anyway, now is the time to make sure
it's well insulated behind it.
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