Installing new corrugated roof

9 Aug 2013
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United Kingdom
My garage currently has a corrugated fiber cement roof which is pretty leaky :(

I've arranged for a company to come and remove and dispose of the old roof panels (as the are likely asbestos containing) and need something new in its place.

I have contacted a few local roofing companies who all seem to want to push me towards a 'flat' roof style arrangement with torched felt at a cost of around £1500 (which by their own admission should last just 10-15 years).

The roof is a bit of an odd shape, the description of the style is apparently 'saltbox' ... Like this ...


The corrugated panels are on the longer rear section, while the small front piece is tiles. Ridge tiles have been mortared over the joint.

I'm a fairly happy DIY'er (and it's only a garage) and have priced up replacement corrugated bitumen panels from Wickes at about £350.
The corrugated panels also have a ridge piece in matching colour (y).

Given that the instructions for these are to nail through the sheet into the beams, how should I finish the tiled side?
The ridge pieces have a matching corrugation which won't sit flush against the tile, and I'm pretty sure that nailing through clay tiles isn't going to work. Is there a better solution?

Also, for the sides. The current sheets are laid on a bed of mortar on top of the bricks. Is there something I can use to seal this joint without mortar, maybe dry verge caps?
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Thanks for the replies. The insulated sheets look like a much beteer solution, especially as they come in long lengths so I can cover the entire length without a jigsaw of panel pieces.

Are they easy to get hold of?
I've searched online an can only find a couple of suppliers, my local places only sell the uninsulated sheets :(
You sometimes have to order and wait for delivery. A lot of branches will only stock un insulated
Thickness of insulated sheets will alter the height of the sheeted part which alters the levels at the ridge, may be a case for spray insulation under standard ones.
Thickness of insulated sheets will alter the height of the sheeted part which alters the levels at the ridge, may be a case for spray insulation under standard ones.

This is a concern. Currently the corrugated sheets are around 50mm high at the upper part. As the front is tiled it is pretty highly stacked, but the ridge has rounded tiles which are concreted in place.
I think the only option is to see how it looks when the old stuff is removed and try and make good.

The insulated panels are only 30mm thick at the highest point and more like 15mm across most of the width. Is 15mm insulation really going to achieve much, or would plain panels and a layer of rockwool on the inside be more effective?
Main purpose of insulation under tin is it helps stop condensation forming which drips down and soaks everything .

If you use Rockwool , it makes a nice little place if rodents get in there..
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I think you can get them with an anti condensation coating - I thing it's like a special fabric stuck on the underside.
Onduline / bitumen type roof panels aren’t terribly waterproof.


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Thanks for coming back to me, can you also take a picture of how its finished against the other end (exposed wall)?

Just looking to see how you waterproofed the panels that end, and what you used for it :)
DCFF58E0-ADE0-453E-8A9A-8D12FAE40C0E.jpeg The end cap isn't on the exposed side of mine at the mo but can be done in a couple of ways.
Either have an overhang of the end sheet and bend it down over a barge board or finish flush with the end and use right angle lengths like in the ones in the picture on my rusty roof by the compost to cap it .post#3
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