Water soaking through shed walls. Help!

[triangularmonkey]

I'm noticed the inside of my T+G shed walls are soaking in water big. At first I thought I'd put a few coats of shed paint to try and seal it up and see how if that resolves it. Unfortunately no luck. Just rained and the inside of the wall is getting wetter and more rotten by the day. Any suggestions?

 

[freddiemercurystwin]

Don't store anything valuable in the shed.

T&G cladding on a shed is not waterproof and never has been. Shiplap is better though can still have the same problem. Shiplap T&G cladding is even better as the outer tongue (if that's the right word) is much lower down than the groove, so minimises the capillary action but I suspect you just have standard T&G.

If you want a waterproof shed you have to apply a membrane to the studs, then air gap formed with vertical battens, then the cladding. Too late now.

 

[triangularmonkey]

Don't store anything valuable in the shed.

T&G cladding on a shed is not waterproof and never has been. Shiplap is better though can still have the same problem. Shiplap T&G cladding is even better as the outer tongue (if that's the right word) is much lower down than the groove, so minimises the capillary action but I suspect you just have standard T&G.

If you want a waterproof shed you have to apply a membrane to the studs, then air gap formed with vertical battens, then the cladding. Too late now.

But Is there anything I can do at all, apart from replace the shed in other words? What about slapping bitumen or roofing compounds all over the thing. Or cauking up the exterior panel joins? Anything?

 

[freddiemercurystwin]

I think some people have tried silicone on the joints, don't know if that works, probably not very well. You could staple a membrane to the inside of the studs but that would leave the cavity unventilated which is not good for the life of the cladding or studs. There's been a few threads like this, have a search using the search thingy in the top right or scroll down a bit for 'similar threads'. Demand a refund if you paid for the shed?

 

[triangularmonkey]

I think some people have tried silicone on the joints, don't know if that works, probably not very well. You could staple a membrane to the inside of the studs but that would leave the cavity unventilated which is not good for the life of the cladding or studs. There's been a few threads like this, have a search using the search thingy in the top right or scroll down a bit for 'similar threads'. Demand a refund if you paid for the shed?

I know it might sound a bit desperate but I'd imagine a bit of guttering couldn't hurt? Can't say I like the idea of reproofing from the inside either and as you said it'll just promote mold and rot. Unfortunately I didn't build the shed, came with the house! Oh well.

 

[freddiemercurystwin]

Yes a gutter will do no harm and may help, depends which way the wind is blowing of course.

 

[Alec_t]

From the pic it looks a though the bottom board is the wettest, from rain splashing up presumably. What ground surface (soil, slabs, ...) is outside the shed?

 

[scbk]

Gutters will make a big difference.

Post a couple of photos of the outside of the shed

 

[triangularmonkey]

Gutters will make a big difference.

Post a couple of photos of the outside of the shed

This might be useful!

 

[Odds]

I think some people have tried silicone on the joints, don't know if that works, probably not very well. You could staple a membrane to the inside of the studs but that would leave the cavity unventilated which is not good for the life of the cladding or studs. There's been a few threads like this, have a search using the search thingy in the top right or scroll down a bit for 'similar threads'. Demand a refund if you paid for the shed?

Silicon works well enough but there's subsequent problems with condensation, so not a perfect solution by any means.
Your solution is as good as it gets and applying a good varnish to the exterior surface of the wood will help.
The damp appears to be along the base of the wall so how much of a gap is under the floor?

 

[Why Not Indeed]

What is the shed sat on?

 

[chris aram]

You've done what I've done on one of my shed walls and fitted the cladding upside down....in other words, the female part of the cladding should be above the male part of the cladding when it joins together. That means rain will drip down the wall and when it gets to the join it won't be able to ingress. If it's upside down (like yours is) then when the rain gets to the gap it will fill up the 'female' U shape and drip into the inside of the shed. Because I've only done it on one of my shed walls and that wall is right up against the neighbour's fence, I'm just going to paint it with bitumen roofing paint to seal the gaps altogether. In your case it's more problematic as the black paint isn't that sightly. You could disconnect each of the wall frames and turn them around or paint the entire shed with some kind of sealant. Good luck!

 

[Why Not Indeed]

fitted the cladding upside down

Are you sure?

 

[JohnD]

We never saw photos of the roof, gutter, downpipes, or base of the shed.

So we don't actually know if one of the common faults is the cause of the wet.

I suspect it is.

 

[chris aram]

Are you sure?
View attachment 334094

Yeah, this isn't the picture from the OP. I'm talking about the OPs TGV ....the pale pine looking picture above, which is the same stuff I've used https://www.diynot.com/diy/threads/water-soaking-through-shed-walls-help.616041/

Sorry, I've just seen the OP posting a picture of the outside of his shed (I assume) which looks like shiplap. The first pictures look like TGV and that's what he calls it. I'm confused now. Either way, I fitted a shed with 3 side the correct way up and have no water ingress anywhere....and I fitted one side upside down and have water everywhere - just like his first picture. Mkae of that what you will