Is this a sensible way to board out my workshop

[Petey83]

A recent thread us prompted me to check my proposed method of insulating and boarding my garage workshop with the more knowledgeable here.

Garage is detached single skin. My plan was to line walls with 1000 gauge Damp Proof sheet and then batten out with treated 50x50mm timber and use 25mm kingspan/Celotex to insulate before birding over with 18mm OSB3.

The floor is will be done at a later stage and this is what the 1000 gauge Membrane was originally for but given the roll is enough for 3 times my garage floor I wanted to try and use for the walls - is this a good idea or do I need a breathable barrier or do o not actually need a damp barrier at all?

 

[RobinBHM]

Ive not heard of expression, I thought you had a bird stuck in your workshop and wouldnt come out

 

[Petey83]

Ive not heard of expression, I thought you had a bird stuck in your workshop and wouldnt come out

Apparently Apple always knows best and changes words for me!! Thanks
For pointing out - hopefully I'll get the replies I was hoping for now

 

[skipdiver]

I'm going with 25mm insulation with taped joints and 11mm OSB screwed directly through the board and insulation to the blockwork. 100mm wool in between the rafters, again topped off with 11mm OSB. Paint it all white and jobs a good 'un. OSB joints and insulation joints to be staggered and i will leave an expansion gap in each corner, which will be sealed with something flexible. I reckon that's a cheap and quick way to do it. The concrete floor will be 25mm insulation and green chipboard. The only downside is the logistical nightmare of doing this in a fully functioning and very full workshop. It will take a lot of moving stuff around and doing it in sections and i'm not looking forward to it, but winter nears and i need to get a move on.

 

[RobinBHM]

For the best insulation without any thermal bridging you could fit celetex straight to the wall with no gaps, fix 2 x 1 battens laid flat then board over with the OSB.

Tape celetex joints

You could fit the dpm 100g plastic to wall to help with damp proofing, although bear in mind you will be screwing through it.

 

[PAC1]

The potential problem is interstitial condensation where any moisture in the bricks condenses and then runs down the inside face of the brick. Where would that condensation go? Sadly I cannot remember how to work it out

 

[Paul200]

I'm going with 25mm insulation with taped joints and 11mm OSB screwed directly through the board and insulation to the blockwork. 100mm wool in between the rafters, again topped off with 11mm OSB. Paint it all white and jobs a good 'un. OSB joints and insulation joints to be staggered and i will leave an expansion gap in each corner, which will be sealed with something flexible. I reckon that's a cheap and quick way to do it. The concrete floor will be 25mm insulation and green chipboard. The only downside is the logistical nightmare of doing this in a fully functioning and very full workshop. It will take a lot of moving stuff around and doing it in sections and i'm not looking forward to it, but winter nears and i need to get a move on.

For what it's worth - that's how I would do it. I think the addition of a DPM would cause more problems than it solves in terms of condensation - as PAC1 points out.

Paul

Edit - I mean the DPM on the walls.

 

[Petey83]

It's the DPM layer that's concerning me as I was worried about condensation.

I'm using 18mm OSB so not sure I want to fix it through the CLS directly to the brickwork as it's going going to have some weight to it plus the walls are running out so think I'll need the batten frame to level them
Min terms of fixings - standard plugs and zinc screws are ok I assume?

 

[stuartpaul]

Interesting .....

I'm about to start on my garage and will be fixing 47 x 47 mm battening to the wall (16 inch centres) with 10 mm (ish) spacers behind. Then extratherm (or similar) seconds between battens then 12 mm plasterboard.

Foil taping extratherm joins eliminates need for vapour barrier.

The 10 mm spacer takes up the unevenness of the extratherm as the seconds are variable thickness.

Ceiling mineral wool, - about 200 mm 'cos that's what I've got.

Last garage was done the same way and no problems experienced. Battens allow for secure fixings to wall, - generally french cleats for hanging 'stuff' from.

I surface run power to allow for easier modifications when required.

 

[Petey83]

Interesting .....

I'm about to start on my garage and will be fixing 47 x 47 mm battening to the wall (16 inch centres) with 10 mm (ish) spacers behind. Then extratherm (or similar) seconds between battens then 12 mm plasterboard.

Foil taping extratherm joins eliminates need for vapour barrier.

The 10 mm spacer takes up the unevenness of the extratherm as the seconds are variable thickness.

Ceiling mineral wool, - about 200 mm 'cos that's what I've got.

Last garage was done the same way and no problems experienced. Battens allow for secure fixings to wall, - generally french cleats for hanging 'stuff' from.

I surface run power to allow for easier modifications when required.

This sounds like they way I will go but hopefully won't need the spacers as much. Looks like I'll just use the DPM for the floor.

Selco have 25m extratherme on special at the moment at £9.99 plus VAT a sheet and 18mm OSB3 is also on special.

 

[MikeJhn]

I built my workshop about fifteen years ago on the Canadian Rain Wall principle, I have not had a single problem with condensation or rain penetration in that time, lots of information on the web on the principle and obviously it does work in the UK.

Mike

 

[skipdiver]

I don't think a DPM is necessary with foil covered boards and i think battens are a waste of time and are a thermal break. I am going with 25mm + 11mm to keep as much room as possible in my shop.