DPM placement

[off_grid_bob]

Hi all,

I'm converting an old wood storage shed (5x3mtr) into a workshop and I need some advice.

The existing shed is single leaf block. There is no DPC and currently a hardcore floor. It's been up for a long time and while it seems sturdy enough, I would rather not go hammering or even drilling at it.

Steps are as follows:
1. Lay DPM
2. Pour a concrete slab (75mm)
3. Frame inside the shed with 3x2
4. Insulate inside the frame.
5. Vapour barrier on inside (warm side) of frame.
6. Sheet with ply/osb/plasterboard.

Hopefully this sounds ok in general?

My main question is how to protect the wooden frame from any possible damp issues coming from the existing wall.
Number 1, I'm not even sure if I should be using DPM or a breathable membrane between the frame and the outside wall?

If using DPM i was thinking of running it right up the wall to the ceiling, but this would probably have to be attached (siliconed) directly to the block wall...does this sound crazy?
I've attached a Pic of the proposed plan.

One more point about the existing shed, it might be relevant..
It's currently open (no wall) on one end (i will be cladding this end). It's abbutted by an old stone walled shed on one side (shed is lime mortared and dry). It also has a greenhouse built onto it out the back. I've attached a Pic of the layout.

 

[^woody^]

If you are forming a cavity, you should not line the outer leaf with a DPM or you will create dampness in the cavity.

If you are forming a cavity, it should be drained - weep holes at the bottom.

If you are lining the wall with a DPM, it's normally tacked to the joists or rafters to hold it in place.

 

[off_grid_bob]

Ok, thanks Woody, I think that makes sense..so I run the DPM up to the joists keeping it tight, THEN I build my frame..no need to tack it to the frame itself?

 

[^woody^]

Image here

www.diynot.com/diy/threads/insulating-single-skin-wall-garage-conversion.595485/post-5282273

And you need to ensure that the timber frame is packed with insulation, no voids, and a vapour check is fitted to the room-side of the frame.

 

[off_grid_bob]

Image here

www.diynot.com/diy/threads/insulating-single-skin-wall-garage-conversion.595485/post-5282273

And you need to ensure that the timber frame is packed with insulation, no voids, and a vapour check is fitted to the room-side of the frame.

Aaah, that's great Woody, much clearer, thanks a million