Workshop leak...

[irishthump]

Wonder if you guys could help with this one,

I've noticed a little damp in my small workshop. Last year I decided to line the walls for a bit of insulation. I place 1 inch foam board between the wall studs then covered this with plastic sheeting, then placed 6mm mdf board on top. The outside of the shed in barrelboard with a breathable membrane on the inside.
A while back I noticed a little damp on the bottom of the mdf at floor level. I removed all panelling and after a heavy fall of rain I can see some small damp patches on the green membrane, but I am at a loss as to where the water is getting in. I have checked the outside and there does'nt seem to be any gaps for the water to get through. It seems worste where the barrellboard cladding meets the upright studs for the wall, could it be seeping through the nail-holes?

Any ideas would be great!

 

[irishthump]

Anybody?

 

[Night Train]

Is the dampness on the green membrane on the inner face or the outer face?

How is the membrane sealed to the wall?

Have you considered condensation?

 

[Woodmagnet]

Can you take any pics of the shed I.T., it would
help to be able to see the problem area rather
than a description. :wink:

 

[PAC1]

It sounds more like condensation then water getting in. Is the layer you put over the insulation a breathable membrane or polythene sheet like visqueen?

 

[irishthump]

Is the dampness on the green membrane on the inner face or the outer face?

How is the membrane sealed to the wall?

Have you considered condensation?

The dampness seems to be soaking through the membrane from the outside.

The membrane is placed between the outer barrellboard cladding and the wall studs. The cladding is nailed to the studs and the nails would go through the membrane into the studs.

I don't think it's condensation to be honest, as it's only occuring in these particular places.

 

[irishthump]

It sounds more like condensation then water getting in. Is the layer you put over the insulation a breathable membrane or polythene sheet like visqueen?

It's just sheets of polythene which I have overlapped and sealed with tape. (Cheap and available to be honest!)
I have taken down the polythene and insulation and there has been a heavy rainfall since and damp patches have reappeared in the aforementioned areas. So I don't think it's simple condensation, what do you guys think?

PS - Woodmagnet, I will post pics sometime today.

 

[irishthump]

Here are some pics...

This is the general area, I have removed the mdf sheeting and the plastic barrier, you can see the membrane between the studs and outer cladding.

I have circled where the damp patches were occuring, as it has dried out now. There was some moisture also along the top of the horizontal batten at floor level you see this clearly in both pics.

 

[Doug B]

Is the green membrane plastic ? If so this could be your problem.

If you have to have a membrane on the outside of the stud it should at least be breathable. Though if you have a membrane on the inside of the stud you don`t need one on the outside.

 

[irishthump]

Is the green membrane plastic ? If so this could be your problem.

No, the green membrane is a cloth-like, perforated material.

 

[johnf]

Whats Barrelboard

 

[irishthump]

Whats Barrelboard

T+G clading with a slightly round profile on the outer face.

Like this...

 

[johnf]

Is the T&G the correct way up

 

[Night Train]

What's the outside of those damp spots look like? Are there any gaps, holes or loose knots there? Any drips from the gutter or roof edge or anything else that might put water directly to the boards? Is any rain puddling or spashing up on to those areas?

As john says, is it the right way up? Tongue should be at the top of each board with the grove at the bottom.

 

[irishthump]

What's the outside of those damp spots look like? Are there any gaps, holes or loose knots there? Any drips from the gutter or roof edge or anything else that might put water directly to the boards? Is any rain puddling or spashing up on to those areas?

As john says, is it the right way up? Tongue should be at the top of each board with the grove at the bottom.

Earlier I examined the boards and found one or two loose knots which I filled. I also filled all the nail holes in the area of the "leaks".
Does'nt seem to be any large gaps and all the boards are the correct way up.
Some rain does run down onto the baords as there is'nt much of an overhang on the roof, maybe this is a factor?

Here is a link to my last thread with a picture of the shed.
https://www.ukworkshop.co.uk/forums/viewtopic.php?p=256647&highlight=#256647

 

[OLD]

Sounds like time to get a helper with a garden hose to identify the leaks for you.

 

[irishthump]

Just to say thanks for all the feedback and help, and it looks like the problem is sorted now.

There seemd to be some major shrinkage between a few boards as well as a few knot holes. These have all been sealed up and it all looks ok so far. Had a couple of really heavy showers sinced I fixed things and no damp patches so far.

At least I can get on with kitting out the shop properly now!

Once again, thanks.

 

[CWatters]

Can you pull out the insulation and put a hose on the outside to see where it's getting in?