Replacing corrugated asbestos-cement garage roof
Simon
beyond repair (I've emergency-sealed cracks and new ones now appear) so
I want to replace it. (I know my local tip will take it with advance
notice).
The company that built it will replace it for not a great deal of money
(about 250 quid I was quoted last year I think) but they will use
fibre-cement sheets.
However I've seen that you can get bitumen type corrugated sheets from
B&Q/wickes etc for about 7 quid a pop.
So the question is, which is the best material for a garage roof? I
kinda get the feeling that with fibre-cement it'll have the same
brittle characteristics and will degrade over not many years. Are the
bitumen sheets any better/worse?
Thanks,
Simon
Chris Bacon
> My garage has corrugated asbestos-cement garage roof, which is cracked
> beyond repair (I've emergency-sealed cracks and new ones now appear) so
> I want to replace it. (I know my local tip will take it with advance
> notice).
>
> The company that built it will replace it for not a great deal of money
> (about 250 quid I was quoted last year I think) but they will use
> fibre-cement sheets.
These are good, as is corrugated iron (which is probably cheaper, too).
> However I've seen that you can get bitumen type corrugated sheets from
> B&Q/wickes etc for about 7 quid a pop.
This is called "Onduline" and is AFAIR made by Johnny Frog.
> So the question is, which is the best material for a garage roof? I
> kinda get the feeling that with fibre-cement it'll have the same
> brittle characteristics and will degrade over not many years.
Well, about 40 or so...
> Are the bitumen sheets any better/worse?
They sag. They sag, lots. They're better if you put them on
Sterling Board, but that adds to the cost.
You could DIY a pitched roof for a few hundred.
Thomas Prufer
>They sag. They sag, lots. They're better if you put them on
>Sterling Board, but that adds to the cost.
They will not take to being stepped on well, and will crack if stepped on in
winter. (Mines are on a double layer of bitumen felt on wood, so are supported
well.) The colored ones lose their color in a few years. No way will it last 40
years or so.
Thomas Prufer
meow...@care2.com
fibre reinforced cement usually lasts very well, its one of the best
for longevity. That doesnt guarantee every batch will, but for long
life its your best bet, short of concrete house tiles or slates.
You can make your own flat fibre cement sheets if you want, it isnt
hard.
NT
Chris Bacon
> Chris Bacon wrote:
> [Onduline]
>> They sag. They sag, lots. They're better if you put them on
>> Sterling Board, but that adds to the cost.
>
> They will not take to being stepped on well, and will crack if stepped on in
> winter.
Thanks, I didn't know that.
> (Mines are on a double layer of bitumen felt on wood, so are supported
> well.) The colored ones lose their color in a few years. No way will it
> last 40 years or so.
I shouldn't think they would, either. Do they (IYE) seem to
encourage moss growth?
Chris Bacon
> You can make your own flat fibre cement sheets if you want, it isnt
> hard.
Interesting. How?
Autolycus
"Simon" <stuffa...@gmail.com> wrote in message
news:1147777569....@j73g2000cwa.googlegroups.com...
As others have said, the bitumen-fibre sheets are sold as Onduline,
Coroline, and as a Wickes own-brand. Worth looking at the onduline web
site for recommendations on pitch, supports, and fixings. I've used it
on a moderately-pitched (20-odd degrees) roof successfully (so far).
Watch out for a few gotchas: it's only available in short, (2m) sheets,
with a cover width of about 850mm; matching ridge cappings are quite
expensive; and the sheds make their profit on the fixing screws.
Box section steel is cheaper, and can span further, but is susceptible
to condensation on the underside, which then drips everywhere, unless
you use a "proper" roof construction. Several ebay sellers offer it in
various finishes and two thicknesses. Beware of the thin stuff (0.5mm)
and a rather rum outfit in Erdington, although I've just finished a 25
square metre roof using both.
The big advantage of steel is that you can buy it in long lengths, so if
your garage has a very shallow front-back pitch, you can avoid end laps,
which are a bit of a pain, especially in fibre-cement sheets where you
have to saw chunks off the corners of the sheets to avoid having four
thicknesses of the stuff.
The SLE cladding site has some useful stuff http://www.slecladding.co.uk
but they're not especially cheap.
--
Kevin Poole
**Use current month and year to reply (e.g. may...@mainbeam.co.uk)***
Car Transport by Tiltbed Trailer - based near Derby
Simon
material, so I'll go with that approach. Is it actually "better" than
the old asbestos stuff, or could my original one just have been badly
installed? I say that because the last roof is probably only 10-15
years old, way less than the 40 years lifetime suggested for fibre
cement.
Thanks all
Simon
Chris Bacon
> Hmm so it seems the concensus is that the fibre cement is the better
> material, so I'll go with that approach. Is it actually "better" than
> the old asbestos stuff
I doubt it's actually better. Could be, though - I'm not sure
how it is made.
> or could my original one just have been badly
> installed? I say that because the last roof is probably only 10-15
> years old, way less than the 40 years lifetime suggested for fibre
> cement.
It's possible. The 40 years I suggested was based on experience
of asbestos cement roofs that have not been mucked about with -
if the roof's been bumped, or structure isn't quite rigid, I bet
it could fall to bits early.
Thomas Prufer
>I shouldn't think they would, either. Do they (IYE) seem to
>encourage moss growth?
The surface of my Onduline is rough, a very fine cross-hatch pattern. Moss and
algae grow on it, but no worse than on the adjacent fiber cement. But it doesn't
take to pressure washing well, whereas the fiber coment does. (Don't
pressure-wash asbestos fiber cement, btw, as it releases the fibers, so they
tell me.)
Also, the fiber cement may be available with an acrylic coating, usually
colored. ISTR something like one or two quid extra for color-coated. Might want
to check.
Thoams Prufer
Autolycus
> Hmm so it seems the concensus is that the fibre cement is the better
> material, so I'll go with that approach.
It's different. For some applications, it may be better, for others,
e.g. as I suggested, long, low-pitched roofs, it may not be. It's
certainly expensive and heavy.
Is it actually "better" than
> the old asbestos stuff, or could my original one just have been badly
> installed? I say that because the last roof is probably only 10-15
> years old, way less than the 40 years lifetime suggested for fibre
> cement.
If it's that new, I'd be very surprised if it is asbestos-cement. Could
second-hand sheets have been used when it was built? There was a
thriving trade in s/h asbestos-cement sheets long after fibre-cement
became the new norm.
If they really are that new, and have failed, I'd be looking very hard
at the underlying structure, to see if it is adequately stiff. If it
isn't, then you've either got to strengthen it or take a chance with a
less brittle material. Or stop exercising the elephant on it.
If you do use fibre-cement, think hard before painting the underneath:
if you make it any less absorbent, you'll get condensation, just like
you would with steel sheets.
keith_765
They tend to sag and curl and they look unsightly being black in colour. The
only advantage is that they are light weight. Cement fibre corrugated sheet
will out last the Bitumen. The down side they are a lot heavier.Have you
consider plastic coated steel sheets. They come in lengths to go in one, are
light weight and easy to fix and come in various colours. Down side is that
you may have to under line with an insulation sheet to stop condensation,
but well worth it.
Keith
raden
<stuffa...@gmail.com> writes
he experienced problems with excessive sagging and condensation
--
geoff
raden
<chris...@thai.com> writes
>Thomas Prufer wrote:
>> Chris Bacon wrote:
>> [Onduline]
>>> They sag. They sag, lots. They're better if you put them on
>>> Sterling Board, but that adds to the cost.
>> They will not take to being stepped on well, and will crack if
>>stepped on in
>> winter.
>
>Thanks, I didn't know that.
>
--
geoff
meow...@care2.com
asbestos sheet _is_ fibre reinforced cement, the fibre used was
asbestos. New fibre cement boarsd simply uses other fibres, eg nylon,
polypropylene, glass.
NT
meow...@care2.com
The material is simply fibre reinforced cement board. 1:3 mix with 5%
alkali resistant chopped glass fibres works fine. 1% polypropylene or
nylon fibre is also used for other purposes, though whether that gives
as much tensile strength as the glass I dont know.
The mould base is a sheet of glass, or ply with polythene on it. 6-8mm
wood is attached round the edges. The mix is made, it must be mixed
properly, and its tamped into the mould. Applying a sheet of polythene
on top will smooth it and keep it damp while it cures.
Flat sheet is less strong than corrugated, hence you may want to use
thicker sheet than the corru. It also looks a lot better.
NT
Chris Bacon
> Chris Bacon wrote:
>>meow2222 wrote:
>>>You can make your own flat fibre cement sheets if you want, it isnt
>>>hard.
>>
>>Interesting. How?
>
> The material is simply fibre reinforced cement board. 1:3 mix with 5%
> alkali resistant chopped glass fibres works fine.
I thought all glass was "alkali resistant"?
? 1% polypropylene or
> nylon fibre is also used for other purposes, though whether that gives
> as much tensile strength as the glass I dont know.
a) I've used this in render, b) getting it evenly spread in the mix
is nigh impossible, c) I doubt it very much.
> The mould base is a sheet of glass, or ply with polythene on it. 6-8mm
> wood is attached round the edges. The mix is made, it must be mixed
> properly, and its tamped into the mould. Applying a sheet of polythene
> on top will smooth it and keep it damp while it cures.
I assume this is all theoretical. Hm?
Thomas Prufer
>Yeah, but they have proper winters in Bavaria, unlike here
Onduline is still crap!
Mine's seven years old, and I can get maybe three more years out of it. It's
been repainted once with bituminous glop: The red color came off after a few
years, and after pressure-washing the algae and moss off (under trees, north
side) the glop looked a good idea. (Glop doesn't last long, though.)
It's on a well-built roof: solid t&g cladding, a layer of bituminous summat
tacked onto that, another melted over it, and the Onduline nailed on that with
special nails with litte plastic heads. It'll be waterproof even if the Onduline
were leaking.
A roof with just Onduline and no layer of something solid under it would be a
sagging nightmare! Once it sags enough for water to pond, freeze, collect
leaves, you'll step out onto it to patch it, fall through, and curse the stuff.
'Pends on pitch, of course.
Still, it's very cheap, easy to use, a breeze to install alone, and quiet under
rain. (You *do* have rain, seeing you don't have winters?)
I'd look for something more durable: Wood cladding and bituminous shingles
hasn't been mentioned yet, I think.
Thomas Prufer
Aidan
Autolycus wrote:
> The SLE cladding site has some useful stuff http://www.slecladding.co.uk
> but they're not especially cheap.
Regarding fibre cement roofing, I think the main product is Marley
Eternit. Besides roofing sheets, the material is also used for tiles,
slates and cladding panels.
http://www.marleyeternit.co.uk/
The list of stockists for roofing is odd (the list of 'your nearest
towns' doesn't include London!) but the list is more extensive for the
tiles & slates section.
I can recall using Marley's asbestos cement slates in the late '70s,
I'd think they've just changed the material used for the fibre
reinforcement.
meow...@care2.com
forgot to mention moulded sheets use a very fine sand. A mix of fine
and the usual would work.
NT
ag.j...@homecall.co.uk
newshound
> These sheets are nothing but cardboard covered in bitumen. They sag with any weight of rain or snow on them and need bracing at 600mm intervals max. I did my son's garage last year and now it all needs replacing. Total rubbish!!
>
equivalents. I did one 25 years ago and it is now about due for
replacing. Don't see why they should sag with rain unless there's no
slope! If you follow the manufacturer's spec they will support the
weight of a sensible adult, but you would not find me on an asbestos
cement roof without proper crawling boards.
Chris French
ag.j...@homecall.co.uk writes
What sheets? Presumably you are talking about corrugated bitumen sheets
eg Oduline?
> They sag with any weight of rain or snow on them and need bracing at
>600mm intervals max. I did my son's garage last year and now it all
>needs replacing. Total rubbish!!
like you didn't follow the installation instructions properly.
--
Chris French
Brian Gaff
And by the way, the plastic sheets are also terrible in that constant
baking and freezing makes the stuff brittle in about three years and the
next wind rips it off.
Brian
--
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This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...
bri...@blueyonder.co.uk
Blind user, so no pictures please!
<ag.j...@homecall.co.uk> wrote in message
news:b629745f-e35d-4ce0...@googlegroups.com...
harry
It's largely caused by the interior of the building getting hot. (Black roofs don't help).
You can reduce the problem by making sure the building has lots of ventilation to keep things cooler.
Maybe some sort of light reflective finish would help too.
Aluminium paint????
Andy Burns
> Thomas Prufer wrote:
>
>> Onduline is still crap!
>>
>> Mine's seven years old, and I can get maybe three more years out of it. It's
>> been repainted once with bituminous glop: The red color came off after a few
>> years, and after pressure-washing the algae and moss off
>
> It's largely caused by the interior of the building getting hot. (Black roofs don't help).
roof, with cross-battens spaced as recommended, nailed using the proper
fixings. Part of it is under a tree but after 4 years it hasn't needed
pressure washing or glop, the rain seems to keep it clear, maybe it's
down to the angle?
Martin Bonner
> In message <b629745f-e35d-4ce0...@googlegroups.com>,
> ag.j...@homecall.co.uk writes
> >These sheets are nothing but cardboard covered in bitumen.
>
> <don't have whatever post you are replying too>
17th May 2006! So not *quite* a decade old - but close enough.