New workshop help to insulate and layers needed.

[MDKKEN]

Hi,

I bought 19 MM cladded shed attached to 4x 2 timber.

As the cladding is attached directly to 4x2 with no gap to the outside to allow free flow of air, what can I do to add insulation, semi permeable membranes and then ply/OSB inside lining.

will this be ok,

1 Cladding - Has been painted with Oil Based OSMO country paint.
2 Semi permeable membrane - attached to inside of the cladding no gap.
3 Insulation.
4 Damp proof membrane
5 External Ply.

Will this work?

 

[Halo Jones]

Hi MDKKEN,

I am in the same situation. I have bought a second hand wooden garage with cladding already attached. I have laid paving slabs in concrete to make a base and have a brick plinth two rows high around the perimeter. The perimeter of the base is a total 50 mm less than the wooden part of the garage (giving 25 mm on each side). Between each of the wooden uprights I plan on drilling through the base into the 25 mm gap between the brick and outer cladding to give air vents at the bottom and have soffit vents at the top just behind where the guttering will be. I will then follow the membrane and insulation regime as you have detailed except the mebranes and insulation will be laid across the uprights to maintain the airgap. This will hopefully allow air movement between the cladding and the semi-permiable membrane to keep things dry. This means the uprights are relatively exposed but I am guessing it should be OK.

If you don't have a base as described above I guess you could have soffit vents top and bottom to give the airlflow?

Anyone have any better ideas?

Halo

 

[Woody Alan]

If you clad the inside with ply or OSB, being WBP, it is virtually a damp proof membrane in itself, so there is no need to line behind it...unless you want belt and Braces. As you cannot fit the permeable membrane behind the cladding in a continuous sheet because of the 4x2 there is not much point in putting it in. In an ideal world the cladding should be on strips away from the 4x2, however that is not going to happen now.
I would leave out the permeable membrane and save the money. When you insulate work out a way of preventing the insulation making contact with the cladding so if there is any damp it won't be held by the insulation. The whole thing should then breathe enough. I have used this method on two wooden structures which have shown no sign of deteriorating or damp over the last few years. I did put a plastic membrane inside as I used plasterboard which had no natural damp proofing.


Cheers Alan

 

[MDKKEN]

Thank you for the reply - a great help!