# Leaky shed roof



## brianhr (25 Nov 2009)

The recent bad weather has found weaknesses in my shed roof. It is only 10ft x 12ft so the work required is small. I have covered it with a tarpaulin for the time-being and have replaced the soggy timbers at the gable ends. 

My question relates to the replacement felt. The existing felt is loose-laid (one layer of a fairly heavy felt) and so is easy to remove. Conventional instructions advise not nailing the felt down from the roll but to open it up and let it 'mature' on site. Is this really essential? Could I fix it at the top of the ridge and let it mature under the tarpaulin before finally nailing it down in the spring? The overlaps would be left unsealed.


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## bigjoe (25 Nov 2009)

Hi Brian,
Ive never matured felt,i normally try and wait for a mild,minimal wind day but a warm day is easier for folding it round edges etc.

You could lay it under the tarp and finish it in the spring even just for some better weather.

Regards

Joe


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## dedee (25 Nov 2009)

Must you use felt?

I'd heartedly recomend corrugated bitumen roofing sheets. Easy to put up, no gluing required and will last a lot longer than felt.

Coroline is the market leader:-
http://www.fascias.com/en-gb/dept_738.html

Andy


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## MikeG. (25 Nov 2009)

Damn, beat me to it! This a much better solution for shed rooves....much better. Simple, cheap, relatively long-lasting compared with felt, looks better, easier to fit than felt etc etc.......

Most Builder's Merchants have their own brands.

Mike


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## cambournepete (25 Nov 2009)

I have seen really thick bitumen paint that is supposed to fill in cracks and holes in existing felt.
No experience of using it though, but I think I'd try that myself before changing the whole roof...


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## MikeG. (25 Nov 2009)

It isn't a question of changing your whole roof, Pete. If you have to replace the felt because it has given up then this simply nails in place over the top. Much better a job than slopping a liquid about hoping it fills all the gaps!

Mike

PS Onduline is another common brand-name.


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## dedee (25 Nov 2009)

With the corrugated sheets, depending on your roof construction, it is also very easy to add a bit of extra light by using an odd clear corrugated panel.

Andy


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## dedee (25 Nov 2009)

I've been searching for this page which I'd lost from my bookmarks.

Excellent info here on how to lay corrugated sheets

http://www.slecladding.co.uk/ondul.htm

Andy


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## devonwoody (25 Nov 2009)

Isnt there a roof felt that is now applied with a blow torch instead of wet bitumen?


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## head clansman (25 Nov 2009)

hi 

yes there is torch on felt , i used GRP fibre glass flat roofing, expensive but very good . hc


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## brianhr (26 Nov 2009)

Many thanks for the suggestions. How did I know Mike would suggest corrugated roof sheets? Actually I have already bought the felt and think the corrugated sheets would look a little too "agricultural" as the shed I inherited is only 18inches from the boundary and rises above the adjoining fence by about 3ft. In fact the shed is only 15ft from my neighbour's back door. I need to be the quietest woodworker around!


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## MikeG. (26 Nov 2009)

brianhr":vxapoew2 said:


> How did I know Mike would suggest corrugated roof sheets? Actually I have already bought the felt



I've never actually liked that rolling eyes smiley, but........ :roll: 

Mike


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## brianhr (29 Nov 2009)

Mike, Forget the rolling eyes. Advice is just that, nothing more. I asked about the problems with laying felt at this time of the year. That's all.


> I've never actually liked that rolling eyes smiley, but......


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## Benchwayze (30 Nov 2009)

So I have a leaky roof on my 'lean-to' garden shed. 

I can see how I fix this stuff over the top, on a framework, and I know how to seal the drip edge and the sides. But how do I seal the front edge, to prevent water running down underneath? 

Looks to be suitable only for ridge-roofing. Presumably there is a ridge moulding available. 

Cheers

John


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## MikeG. (30 Nov 2009)

Benchwayze":1kkfsbpj said:


> I know how to seal the drip edge and the sides. But how do I seal the front edge, to prevent water running down underneath?
> Looks to be suitable only for ridge-roofing. Presumably there is a ridge moulding available.
> John



By "this stuff" I assume you mean Onduline (or equivalent)? There is a ridge, and there are gable-end pieces as well. I don't follow "seal the front edge".....do you mean the eaves (where it runs into a gutter)?.........or is it that you have a mono-pitch roof, and are referring to the highest point (still called a ridge, I believe)?

Mike


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## dedee (30 Nov 2009)

full fixing instructions for onduline or equivalents here

http://www.slecladding.co.uk/ondulfix.htm

edit,
One tip I would give is try to find roofing screws rather than nails just in case you need to take a sheet up for repair.

Andy


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## Benchwayze (30 Nov 2009)

Yes Mike.. 

There's only one pitch or slope; which has nothing to do with 'planes'!
 :roll: 

I call it a lean-to construction, (although it's a free standing shed) and the front-ridge or head is the bit I am thinking of.

The reason I ask is that I was thinking of putting some kind of corrugated plastic on the top, but I would have had the same problem. This rigid felt sounds ideal!

Thanks for jogging my grey cells on terminology...

Regards
John


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## Benchwayze (30 Nov 2009)

dedee":3inymiqq said:


> full fixing instructions for onduline or equivalents here
> 
> http://www.slecladding.co.uk/ondulfix.htm
> 
> ...


I was ahead of you there Dedee. I had already thought about using an ordinary screwdriver rather than a Birmingham one!

Cheers
J.


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## adzeman (1 Dec 2009)

I have been following this post with interest as I had the same problem earlier in the year and I thought solved it. Went down the bituminised corrugated sheet road.
Guess what?
Went into the workshop yesterday to the sound of dripping water.

oh dear it never rains it just pours down.


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## devonwoody (1 Dec 2009)

We had 90mm of rain in Devon over the past 7day, and it was heavy, I expect the rain overflowed the corrugations and crept in that way?

Through the holes made for holding sheets down?


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## adzeman (2 Dec 2009)

You are probably correct in your analysis, need to get up there and look. Its leaking in a different area then last time.
Because of time restrictions I only repaired the defective area, should have done the lot.
Where I had the big leak I installed a roof light and to support the flashings boarded it with 19mm waterproof ply. The Roof nail went into this so I think it is the sheer volume of rainwater creeping up the edges.

It is a drip and not a deluge as previous. Have some pictures but cant post from home. Cant get Broadband from our village, but if interested will post from another location.


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## OPJ (2 Dec 2009)

devonwoody":3hkf7obo said:


> We had 90mm of rain in Devon over the past 7day, and it was heavy, I expect the rain overflowed the corrugations and crept in that way?
> 
> Through the holes made for holding sheets down?



What I've found with my roof is that, because the each sheet is only overlapped by one corrugation (less materials, less work, etc. :roll, this gives rain water an excellent opportunity to find a way in to my workshop! :x I also find it creeps in around the fixings.

What I've been meaning to do for some time is to get up there and just fill all these gaps with sealant. One thing I like about the Onduline system is that you can _over sheet_ without having to remove the old covering (particularly important if it's asbestos). With this though, they do recommend you coat both sides of the old sheets with a thin 50/50 mix of PVA, which sounds like a good idea to help keep the dust down if you did decide you wanted to remove it...


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## adzeman (3 Dec 2009)

My problems started when we had the snow earlier this year. Its was wet and sticky and laid about 100mm thick. This put weight on the corrugated bitumen sheets which deflected.
When the snow melted the sheets did not go back to their original shape.
Rain as you described entered the work shop. The underside of the roof is insulated for sound which became wet turned into a stogy mess, a nightmare!
The sheets do flex with the wind and move and distort in hot sunlight.
The half of the roof I replaced was built up with 19mm ply, coated with bitumen paint and the original corrugated sheets replaced with new sheet nails. Flashband was used to flash the upstands, any joints in the plywood and as an eaves flashing into the gutter. Any rain getting past the overlap just travels down the ply sheets into the gutter.
Just whish I had done the other half of the roof, which I will do next dry period.


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