Garage Roof Advice

[cf-leeds]

I need to replace a very leaky old garage roof, which is currently in corrugated asbestos sheets (I think they're asbestos anyway). I'm aware of the disposal process for old asbestos roof and I have details of the local council disposal process for asbestos - I'm ok with all that.

My question is what's the best replacement for the roof.

It's a flat sloping roof with a single gutter across the back end of the garage - It's a prefab garage. (not a pitch roof).

I thought I'd just look online for some galvanised corrugated metal sheets, around the same dimensions at the old asbestos, but I find there are many products out there, including corrugated bitumen sheets.

Can anyone offer some advice on a good option here.

My main criteria are, easy to install, good-value, long lasting in terms of no discolouring, if they happen to be dark great for example. Is there anything that you'd definitely avoid ?

Any tips welcome.

Thanks in advance.

[Chris Hogg]

Onduline?

[Michael Chare]

We had a double garage roof recovered with edpm which is black. It is on top of boards much of which was there before. Another approach is to use glass fibre.

[williamwright]

Seconded. I vaguely remember that there's different grades available for some similar products.

Bill

[Bev]

Onduline is the heavier being c3mm; Coroline is 26.mm 'other brands' such as may be found on the link are thinner and more flexible. I did the shed roof last autumn using Onduline from (ISTR) Roofing Superstore as the best value for me. Use the proper fixings for it whichever brand you go for. A (limited) range of colours and pitch sizes also can be found in Onduline

[newshound]

The problem with Onduline or Wickes own brand corrugated bitumen is that it is only rated for 10 years life, especially if the slope is shallow or the purlin spacing large. I need to replace my shed's roof this year, admittedly that lasted 25 years, but we rent a stables where it has failed badly at 10 years. Basically, it sags and then tears. It will certainly last longer if you board underneath it with sterling board. I have not quite decided whether to do that with mine, or whether to convert to plastic coated steel, or perhaps to corrugated fibreglass (which is a bit more expensive).

It gets slightly lighter in colour over time, not enough to matter IMHO.

Metal sheet comes in a range of thicknesses and geometries. The thinnest (eBay) lasts pretty well, it is light and pretty easy to cut and fix. If in a windy area you need to make sure the edges are well fixed down.

[Harry Bloomfield, Esq.]

cf-leeds laid this down on his screen :

The modern equivalent of the corrugated galvanised metal, is a squared box section, galvanised and painted in various colours. It comes in two thicknesses, get the thicker one - less chance of it denting. Also get the special self sealing bolts/screws for it.

You can get plain or ready insulated underside.

A very easy DIY job, with probably no need to cut the sheets. If you do need to, the maker suggests cutting with a scissor like implement, which will seal the cut edge with galv..

I did both my garage and workshop roofs with it, 10 years ago - no complaints here.

[Brian Gaff (Sofa]

Is not that very flammable for a garage? However definitely avoid plastic. It goes brittle in just a few years, at least all the stuff I had on my roof did, but now the garage is gorn and a nice flattish bit of concrete remains. grin.

Brian

[Murmansk]

I did mine in box profile sheeting - like they make the walls of BQ and other sheds from.

Comes in various colours and it's produced in whatever lengths you ask for

[nothanks]

I agree, excellent stuff and quick to fit. I did the roof and walls of a blockwork shed last year, put 50mm celotex "seconds" under the wall panels and between the rafters, then plasterboard'ed. It's now a very snug shed! A couple of years before I replaced part of the asbestos wall panels on a much larger shed and hope to finish it this year, but the timber battens are rotten so it's a larger job.

[newshound]

Not sure how the proper farming/industrial stuff over here is fixed down. The cheap stuff that I have used is just screwed through the high spots with a sort of domed plastic cap over the screws. I agree, it doesn't need much slope for water but of course here we also need to cater for snow.

[Andy Burns]

What's on sale in Wickes isn't Onduline (or wasn't a few years back) it's Coroline, which is a bit thinner, surprised they haven't been pulled-up for it (or maybe they have actually changed what they sell?)

[PeterC]

I bought all the makings for my second shed from Wickes about 12 years ago It was dfinitely Onduline then. I did quite a bit of research to avoid the thinner one. I see that Wickes is selling Onduline at 3mm - that's correct; what it actually is... A few years ago ISTR that it was branded as Wickes and thinner than that which I bought. Next door's shed was re-roofed in a corrugated sheet that looked remarkably like asbestos cement. The roofer (lives about 150 yds up the road) said that it should last for about 50 yeras.

[Chris Bacon]

I'm doing a similar thing. I think I'm going to use 3" corrugated galvanised rather than plastic coated, on 11mm Sterling board. I don't want bitumen or felt, might use EDPM but prefer corrugated.

[fred]

I've built two sheds over the last 30 years and both were roofed in galvanised corrugated steel. It was the cheapest I could find and has lasted so far with no sign of degradation. Its what farm buildings traditionally used.

[newshound]

It does look a bit agricultural in a domestic setting though (whereas even cement-asbestos weathers in and more or less goes with brick and tiles).