Fixing battens and penetrating DPM

DPM should be on the warm side of the insulation...

I understand (and have applied) that principle for walls and roofs, but that's not really applicable here - this is a DPM to prevent damp getting into the floor from underneath, not to prevent condensation from the inside. It has to be between the concrete and the battens. So I think this is a bit of a red herring.

Cheers Richard

I'll answer my own question, and say that I think I probably need to be using a liquid DPM, that I'll only make tiny holes in when I hammer fix, rather than a sheet DPM that could tear. Conceivably I could even bond the battens to it rather than hammer fixing.

Still interested in opinions, or is everyone bust reacting in their various ways to today's celebrity death? ;-)

Cheers Richard

Why do you need to fix it down? Its not going to fall up after all!

Mike

On Monday 08 April 2013 15:05 geraldthehamster wrote in uk.d-i-y:

Hi,

The simple answer:

Don't worry about it.

Use corrosion proof screws or nails to fix down. The area of the pucture holes is trivially small and nearly all blocked by the nail.

Unless you have liquid water, the microscopic amount of water that permeates through will be able to escape through the floor or round the edges.

Seal the surface of the floor.

Along the line of the proposed batten, lay mastic ribbon.

Lay the edge of your DPC on the mastic.

Place the batten and nail down.

Roll the DPC back to the just-fixed batten.

Lay another line of mastic where the next batten will be fixed.

Roll the DPC over the mastic. Nail the batten.

And so on.....

Annette Funicello? Yes, yes, a great loss. And she was only 70.

Nick

Thanks, and to Tim for your reply (we should compare bungalows).

Cheers Richard

How much moisture are we talking about? If it just gets "a bit damp" then I wouldn't worry - just use appropriate fixings that aren't going to rust and fail (quickly).

Question for those more knowledgable than I: Will an air gap be needed between the DPM and the insulation? I thought it was standard practice so that any moisture that does get in doesn't end up trapped in the insulation layer, but perhaps not. (It's relevant to me because I want to put an insulated floor into my basement at some point, now that I've got water ingress via the walls issues sorted out, and every bit of height that I can save is a good thing! I've been factoring in an air gap, but it'd be nice if I didn't have to bother)

cheers

Jules

It's not the fixings I'm concerned about, it's keeping damp from penetrating the battens, due to the lack of DPM in the slab.

Air gaps are relevant when putting insulation up against timber rafters that need to be ventilated. If you're laying insulation on a concrete slab you wouldn't have an air gap. It sounds like you might end up laying the same kind of floor that I plan to.

Cheers Richard