Thread: Shed leaks!

Lift the roof sheet above the leak and you should be able to see the water track to get an idea how far up the roof the leak is.
Check the neoprene washers under the screws as well, it is surprising how much water you still get through a poorly seated roofing screw.

Or water test in sections with a hose to try and recreate the leak

Originally Posted by BobL

I've been on the roof and can't see anything obvious apart from perhaps insufficient tek screws holding the flashing on but if the water came in that way I would expect it to rum down the inside wall.

Had a closer look at that line of flashing and there are only Tek screws about every metre apart leaving up to 2mm wide gaps in between the screws so I've added about 15 more Tek screws so they're about 300 mm apart and no gaps.

It's weird because along the other main line of shed flashing those screws are much closer together. Ordinarily I would say that maybe the builders ran out of screws during the build but that was not teh case as they seem to have wy more fasteners and materials. Amongst the stuff they left behind were boxes of TeK screws of various sizes and 10 sheets of Colourbond

Whats that song? "there's a hole in the roof dear Lisa dear Lisa a hole. Well fix it dear Bob fix it."

Originally Posted by rod1949

Whats that song? "there's a hole in the roof dear Lisa dear Lisa a hole. Well fix it dear Bob fix it."

Now that's showing our age.

Anyway I thought it was a "bucket"?

Do you get frosts there and if so only shows up when there is a frost

Originally Posted by rwbuild

Do you get frosts there and if so only shows up when there is a frost

Leaks only when it rains. The more it rains the more it leaks. I put a 2L ice cream container under the leak and even when its raining hard it takes several hours to fill it - I usually empty it morning an evening and that stops it overflowing. A few a days ago we had 44mm and that's the only time the ice cream container has overflowed in the last year or so.

Bob,
I had intermittent leaking of my shed roof. I couldn't work out why after some rain, no leaks and other rain it would leak. Eventually found the problem, the shed builders hadn't laid the corrugated iron right to the edge of the shed frame so the flashing was only over one rib instead of two. Further, they had put about four or five screws in the lower run of the corrie' before the flashing had gone on. I decided the rain was getting blown in under the flashing when the wind was from the Sou-east. Since the sheets were held in place by the usual screws through the top ribs and the ones in the lower were no longer necessary I removed them and silastiked the holes. No leaks since then.
I hope this is not too confusing, as I don't know the correct terminology for the ups and downs of corrugated iron ribs.
Cheers,
Geoff.

Originally Posted by Boringgeoff

Bob,
I had intermittent leaking of my shed roof. I couldn't work out why after some rain, no leaks and other rain it would leak. Eventually found the problem, the shed builders hadn't laid the corrugated iron right to the edge of the shed frame so the flashing was only over one rib instead of two.

That appears to be EXACTLY what has happened.

Along that 6m of flashing there were 7 screws (ie 1 per m) but there was no screw at the flashing join and there were mm gaps in several place between the screws.

There have been no more leaks since I added the extra Tek screws, but have yet to have a really heavy downpour.

I think we're in for one this afternoon, Bob.

Originally Posted by Boringgeoff

I think we're in for one this afternoon, Bob.

We just had about an inch or more of rain in the last hour - shed roof still leaking but not as bad.
It strongly hints at what I have to do and that is extend the flashing over to the next ridge of roof sheeting.
Or maybe just get some of that sticky black double sided tape and seal the existing flashing to the roof with that?

Could be they failed to turn up the valleys under the ridge flashing. Pretty common place for water ingress and it can just run down the underside of the sheet / top of the insulation from there. Usually only leaks if there's a bit of wind blowing the water back up under the flashing.

If you still suspect it's the edge flashing, use Crommelin Superseal if you can squish it between the flashing and the sheet. It's a closed cell UV stable foam that squishes nicely when you tek screw it back down. Relatively cheap, available from Bunnings and water will never get past it.

Take a photo next time you're looking at it so we have an idea what you're working with.

Thanks Moph,

Originally Posted by Moph

Could be they failed to turn up the valleys under the ridge flashing. Pretty common place for water ingress and it can just run down the underside of the sheet / top of the insulation from there. Usually only leaks if there's a bit of wind blowing the water back up under the flashing.

It's not at the ridge cap - they do have the valleys turned up and sealed those with foam.
It appears to be the roof flashing down the slope of the shed.

If you still suspect it's the edge flashing, use Crommelin Superseal if you can squish it between the flashing and the sheet. It's a closed cell UV stable foam that squishes nicely when you tek screw it back down. Relatively cheap, available from Bunnings and water will never get past it.

I have bought some double sided roofing tape and today is supposed to be dry so will give it a crack.

Take a photo next time you're looking at it so we have an idea what you're working with.

Below is a diagram - the is the gutter end of the shed - well I took the gutter off as it was constantly choking with leaves and the runoff ends up in the same patch of garden anyway.

Blue line shows where I reckon water is getting in - its also the direction of prevailing winds.
Roofing insulation under red arrow is saturated and water drips off roof sheeting at black arrow.

I tripled the number of Tek screws that hold flashing down which worked for light showers but when we had 30 mm on Friday/Sat the amount of water leaking into shed was about 3L, so much less than usual but it's where it falls (right into my drill bit racks) that is a nuisance.

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Is there a turndown on the flashing at the blue arrow?
If there isn’t there needs to be and is your problem

Originally Posted by Beardy

Is there a turndown on the flashing at the blue arrow?

There is a small turndown on the flashing (blue arrow), but its poorly located and was not making contact all the way along the roof sheet underneath it as it only had 1 screw per metre.
Have since added 3 screws per meter but there are still small <1mm gaps in some places. I'm going to seal that whole line with double sided roofing tape this morning.


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