Shed Roof Repair

[A1Dan]

My shed roof had new felt fitted 18 months or so ago - I know this as I was renting the house at the time, but have now bought it. So the felt is in good condition still, but over winter it has been letting water in where the joins & nails are. You can see from the outside where the dampness is building up around them (one join in particular):

At some point I'll be looking at replacing the whole roof with something better, but that's down the list of jobs at the moment! Hoping there's a decent solution to tide me over for now... any kind of tape nor similar that'll keep it watertight for another year or two?

 

[Harry Bloomfield]

At some point I'll be looking at replacing the whole roof with something better, but that's down the list of jobs at the moment! Hoping there's a decent solution to tide me over for now... any kind of tape nor similar that'll keep it watertight for another year or two?

Difficult to tell, but - If the lean of the roof, is away from the camera position, then the overlap has been done the wrong way.

 

[A1Dan]

Difficult to tell, but - If the lean of the roof, is away from the camera position, then the overlap has been done the wrong way.

Good shout, I think you might be right actually... I'll need to get up a ladder and check when it's light, but the far side / top of photo is lower, and it sure looks like the lowest / furthest felt lies on top of the middle one, doesn't it?

Pretty dumb if so... I know nothing about felt roofs, but pretty sure it would have occurred to me to do the overlap so the water runs downwards!

I guess if we're right, then the only sensible answer is pull it up and start again?

 

[foxhole]

You could throw a tarp over it , cheap and quick , if recovering just overlay with Epdm , cheap enough on a small shed .

 

[A1Dan]

So, got myself up a ladder to have a proper look, and all is not as we'd thought...

Firstly, the overlap is done the correct way - the below photos are the other way round from the long distance one, with the roof sloping down from the top to bottom of the photo.

Secondly, what I took from a distance to be pooling damp patches are not! The dark patches are actually a tar-like mark, presumably something that is meant to seal the roof?
Edit: Scratch this part... I just looked from the bedroom window again, and the main patches towards the centre and left on the original photo have gone... and they are much darker than anything on the below anyway. So they *were* damp patches after all, they've just dried out over a couple of days of little-to-no rain!

Whatever it is it's obviously not working, as the beams inside have patches that are pretty consistently damp other than in warm dry spells, and actively drip if it's been raining much!

 

[A1Dan]

You could throw a tarp over it , cheap and quick , if recovering just overlay with Epdm , cheap enough on a small shed .

A tarp could be a practical solution while the shed awaits its long-term future (it's possible I may be looking at moving it in a year or two)... are there any real draw-backs if it's securely attached other than the aesthetic appearance and long-term durability?

Didn't know anything about EPDM, but having read up it certainly looks a solid solution... but more a long term thing that needs applying properly, as new felt would, right?

 

[Harry Bloomfield]

Secondly, what I took from a distance to be pooling damp patches are not! The dark patches are actually a tar-like mark, presumably something that is meant to seal the roof?

That, was what concerned me too! With those better photos, it appears to be a fair job. You don't usually get leaks where the clout nails are inserted, because the felt seals against them, and it looks as if it has been torched on.

2nd photo, close to the top/back, on the right - Is that a tear in the material?

 

[A1Dan]

That, was what concerned me too! With those better photos, it appears to be a fair job. You don't usually get leaks where the clout nails are inserted, because the felt seals against them, and it looks as if it has been torched on.

2nd photo, close to the top/back, on the right - Is that a tear in the material?

Nope, that's a twig, if I'm looking at the same thing!

Still no clearer on what's causing the ingress then. Next time it's been raining a lot I'll go and give the inside a closer inspection... pretty sure the leaks line up with the joins in the felt, but may be able to spot more specifics...

 

[Harry Bloomfield]

Still no clearer on what's causing the ingress then. Next time it's been raining a lot I'll go and give the inside a closer inspection... pretty sure the leaks line up with the joins in the felt, but may be able to spot more specifics...

I'm not seeing any indication of an overlap, where the joints are. That might point be worth checking. If you find it is those joints, get a tub of Blackjack, to paint along the joints, as a quick fix.

 

[opps]

That, was what concerned me too! With those better photos, it appears to be a fair job. You don't usually get leaks where the clout nails are inserted, because the felt seals against them, and it looks as if it has been torched on.

2nd photo, close to the top/back, on the right - Is that a tear in the material?

Why would they nail down torched mineral felt?

 

[Harry Bloomfield]

Why would they nail down torched mineral felt?

Who knows, but someone did.

 

[opps]

As a short term fix, something like a small tin of IsoFlex might work for a couple of years.

The tarp option- A cheap blue tarp will break down in less than a year, they tend not to be UV safe. The last one that I purchased from Wickes to build a temporary cover down the side of the garage so that I could spray MDF started to shred blue specs after a week or so at the height of summer.

I recently purchased some clear, thicker cross stitched, clear tarps from Leyland SDM. After a year in the sun, you can push your finger through the stitched bits.

A decent tarp will probably cost more that the original roof felt.

On the upside, you can apply more felt over the existing felt and use a product such as Isoflex as a short term fix.