Large shed / summer house leaking

[mrtnpaletmo]

Hi all


Hoping someone can help with my current predicament. Just to be clear I am not sure on what to do and have scoured the internet for some advice. Hoping someone can tell me whether I am in the right track or I am crazy and should pull it down.


I have a log lap shed which was built as an office by the previous owner of the house. To cut a long story short it leaks on 3 walls and the tongue and groove boards at the end are either water damaged or rotting. It all started off as noticing that the plasterboard was wet in one corner.

My not so clear plan is to either get someone in or do the following myself

• Refit cladding
• Paint cladding walls with something like ronseal water seal
• Seal cladding inside and out with waterproof sealant ( I already started this but noticed water was still coming in)
• Add a breathable membrane over the inside so it covers the walls
• Install pir insulation
• Cover with a vapour barrier
• Fit plasterboard

I have pulled the rotten floor board and the base only has visqueen on the bottom of the joists and no where else. Insulation ( polystyrene) sat on the concrete floor which were soaked through


My thoughts here are

• if floor joists are rotted, fit new ones parallel to existing ones
• Cut Dpc sheet to size and fit into gaps?
• Fit pir insulation onto membrane
• Maybe use marine plywood to sit on top
• Fit a dpc skirt around bottom of shed so that no splashing or rain water can hit the concrete floor.

I seem to be going round in circles and so would welcome any advice

 

[freddiemercurystwin]

The big issue there is that they've not fitted a breathable membrane to the studs on the outside, then an additional batten onto the studs to create a ventilated cavity, then fit the cladding. And I don't see that in your proposal either. You don't need to be faffing about sealing cladding, it is a rainscreen not a waterproof layer, assume that some rain may get through the cladding but ensure it can drain out to the outside without getting the inside wet. Suggest you look up the principles of timber cladding as rainscreen cladding. Tyvek Housewrap would be a suitable membrane, there are plenty of alternatives though.

 

[mrtnpaletmo]

Hi Freddie

Thanks very much for this. Can I ask how big the ventilated cavity would need to be in your opinion. Any thoughts on the rest of my “plan”.

Off to learn about timber cladding as rain screen cladding

 

[Larry1990]

25x50mm treated battens is commonly used to created the vented cavity for these sorts of buildings, just enough for any rain that does make it through the cladding to run down the breathable membrane and drain out the bottom or for air flow to take care of it.

 

[JohnD]

rain is mostly kept off by the roof and eaves. show us some more pics of them.

I can't see a gutter. How does the rain go away?

cladding is usually shaped to throw off water, and the gaps should not be caulked. Show us some closeups of the inside and outside boards and, at the corners, the ends of the boards showing what shape they are. Ship-lap is best. Weatherboard will do.

Log cabins are usually made with a sort of very large tongue and groove to interlock and keep water out.