damp-proofing a garage
Fred
I have a single-skin brick garage. It appears as though the DPM is at
ground level! I'm sure the garden has not been built-up so I think
this was a mistake by the builders. When it rains heavily and puddles
form on the ground, sometimes these seep into the garage.
Inside the garage one wall has been painted, the other is bare brick.
I am finally about to line the walls with insulation and plywood but
am wondering what to do about the brickwork first. On the painted
wall, a couple of the bricks at ground level have peeling paint. That
could be due to age (I've never painted them since moving here) but I
think the bricks may be a little damp but it is only one or two bricks
on the bottom course.
Without digging up the floor and laying a new membrane, what are my
opinions? Would painting the walls with a waterproof paint help or
would that make things worse? I was thinking either bitumen paint or a
special waterproofer. I found this:
Though don't know anything about it.
Would you paint the bottom few courses only or the whole wall? I was
thinking of painting inside rather than outside but would it be worth
painting the bottom courses outside too? I think in the past they had
black masonry paint on them.
TIA
js.b1
garage.
If the outside ground is higher.
Dig a ditch, line with membrane, set in a perforated land drain in
gravel. You can get 80mm in 25m lengths quite cheaply on Ebay.
Bitumen paint for walls.
Everbuild do a D.P.M. which is bitumen with latex as I recall, costs a
bit more tho. Wet the brush with water, then dip in the tin and onto
the walls. Walls from ground to ceiling and floor if necessary
although I suspect a liquid DPM you can pour is probably better
(someone will be along shortly).
Treated battens on wall.
Screw treated battens to wall, then infill with insulation, insulation
over the top ideally re cold bridging, them board out. The insulation
& PB does not touch the floor so any leaks can not wick up the wall as
it were.
jo...@jjdesigns.fsnet.co.uk
I really enjoyed watching that. A good one.
Had a wry smile though with the shot (morning) of big Al painting a
first spot of DPM on the wall. Come going-to-the-pub time he then
proudly shows what seemed an acre of walls and floor covered in the
black stuff. It didn't quite ring 100% true :)
Vernon
Celotex website advises to place insulation against wall, then batten on
top to form a cavity, and cables for sockets etc can run in the cavity.
Then put plasterboard or in OP case ply on top.
NT
but he makes a boob re the dampproofing. If you put the VB on the cold
side of insulation as he did, condensation is likely, and it cant get
out. Fit any insulaiton, then add a VB on top.
Dig and backfill with gravel should work if you can provide drainage.
NT
js.b1
Bitumen on wall, then p/t battens, rockwool between battens, celotex
over battens, foil tape over joints, PB over celotex, taped joints.
If you do not bitumen a single leaf wall you will get chronic water
ingress.
If you do not tape the joints of the celotex or tape PB, you do not
have a vapour barrier.
So basically he was relying on 2 vapour barriers.
Fine as long as that in the middles does not fail - and there comes an
issue re "drylined socket accessories" in something like a kitchen.
The moisture can get in, can't get out of the PB, can't get out of the
wall. One reason why I always insulated behind backboxes to remove the
cold bridge which worked superbly on a test kitchen (just 6mm Marmox
is enough, but I used 12.5mm since I had bits kicking about).
In the middle go p/t battens - and hopefully stainless screws where it
is single leaf brickwork.
The only foolproof way would be to turn it into a "pool shower room".
Seal with wall with Primer-G / Primer -S / SBR, then Mapei Keraflex,
then Marmox in 6-50mm thickness, then polyurethane sealant & tape the
joints, then plaster skim with tiles or whatever on top. The problem
is that gives too low a U value for most applications, it is however
very waterproof. Stick a piece of Marmox behind any backboxes, since
it is extruded polystyrene it is tough enough to work ok.
There is no perfect solution, I too do not like even p/t battens in
any wall which gets damp and much prefer bonding the insulation to the
wall. In that respect I am surprised there is not a "Marmox-PIR" (ok,
there is, but rarely found) in terms of a cement & glass-fibre backed
PIR which can be bonded directly to the wall with Keraflex. That
ensures nothing is getting through your single brick skin (or double
solid brick which can be just as bad in certain circumstances).
NT
Ah, that makes more sense :) I only saw as far as the bitumen coating
and cutting a doorway out.
NT
Fred
wrote:
>Bitumen paint for walls.
>Everbuild do a D.P.M. which is bitumen with latex as I recall, costs a
>bit more tho.
Does anyone else have an opinion on bitumen vs. "dpm paint"?
I haven't found anyone selling the Everbuild one but Wickes do a
rubber/bitumen paint specifically marketed as a dpm and the reviews on
its web site are good.
I read here that two coats of bitumen paint would work. Would I need
two coats of the dpm paint or can I save myself a coat if I buy the
special dpm paint?
TIA
js.b1
> I haven't found anyone selling the Everbuild one
http://buildingsuppliesdirect.co.uk/product/Everbuild-Bitumens-D.P.M./3817
Google for Everbuild d.p.m. - there are other suppliers.
> but Wickes do a rubber/bitumen paint specifically marketed
> as a dpm and the reviews on its web site are good.
Probably the same stuff. It is nothing magical.
> I read here that two coats of bitumen paint would work. Would I need
> two coats of the dpm paint or can I save myself a coat if I buy the
> special dpm paint?
See the instructions.
For floor use I recall Tommy Walsh used 3 coats on the "stick-built-
glass-box" on Challenge Tommy Walsh, the one with the "French idea"
outside CU which was moved inside. For walls I suspect a single coat
will do - not read the tin. He wet the brush in a bucket of water
before dipping into the D.P.M. otherwise it gets rather tiring to
apply... probably a hoard of minions working off camera :-)
NT
I dont expect dpm paint would be anything but bitumen
NT
harry
> Hi,
>
> I have a single-skin brick garage. It appears as though the DPM is at
> ground level! I'm sure the garden has not been built-up so I think
> this was a mistake by the builders. When it rains heavily and puddles
> form on the ground, sometimes these seep into the garage.
>
> Inside the garage one wall has been painted, the other is bare brick.
> I am finally about to line the walls with insulation and plywood but
> am wondering what to do about the brickwork first. On the painted
> wall, a couple of the bricks at ground level have peeling paint. That
> could be due to age (I've never painted them since moving here) but I
> think the bricks may be a little damp but it is only one or two bricks
> on the bottom course.
>
> Without digging up the floor and laying a new membrane, what are my
> opinions? Would painting the walls with a waterproof paint help or
> would that make things worse? I was thinking either bitumen paint or a
> special waterproofer. I found this:
>
>
> Though don't know anything about it.
>
> Would you paint the bottom few courses only or the whole wall? I was
> thinking of painting inside rather than outside but would it be worth
> painting the bottom courses outside too? I think in the past they had
> black masonry paint on them.
>
> TIA
It helps a lot if your garage roof has gutters and downpipes so that
water from the roof is conducted away from the building. Water
falling from the roof can otherwise end up running down the walls esp.
in windy weather. It's worst of all if the overhang of the roof is
small.
Fred
wrote:
>I dont expect dpm paint would be anything but bitumen
It claims to be a mixture of rubber and bitumen but strangely it is
cheaper than bitumen paint, so I wonder whether it contains less
bitumen or whether the price is lower because of economies of scale:
perhaps they sell so much dpm paint they can offer it for less?
Fred
I already have some bitumen paint, so if it is just as good, I will
use that up and save buying a new tin.
One wall is bare brick, so that's straightforward enough but the other
wall already has paint on. Can I paint bitumen/dpm paint over the
existing paint or will I have to strip the existing paint first?
TIA
zaax
Have you working out why the walls are getting damp?
--
---
zaax
Frustration casues accidents: allow faster traffic to overtake.
Fred
wrote:
>Have you working out why the walls are getting damp?
The walls are not damp at the moment. I felt them the other day to
check. When it rains heavily some puddles form inside but I wonder
whether the water passes through the first line of mortar rather than
the first line of bricks? Anyhow, I've never known the walls get damp,
only the floor and only then when we have had very, very heavy rain.