Boarding out single skin outhouses

[Peanut39]

HI

I have a collection of single skinned rooms joined to the back of the house, (a coal shed, utility room, toilet). All constructed on a single brick wall, (ie; not cavity wall).

I'd like to make something out of these but being single skin, concrete flor and flat roof they are COLD. I'd like to board them out to keep the cold and damp out. Not too fussed about building regs - these are just for us to use not to advertise.

The Plan is;

1. Fix 25mm x 25mm exterior timber to the walls

2. Nail heavy gage polythene sheet to the battens

3. Glue / fix rockwool insulation to the polythene, inbetween the battens

4. Screw 'green' plaster board to the battens and tile or paint

Can anyone tell me if I am about to make a huge mistake, have missed anything out or should do something differently.

Kind regards all

 

[Deluks]

foam board such as celotex/kingspan/ecotherm would be better on the walls, easier to fix, near enough twice the performance of rockwool.
You do not want any poly on the cold side (warm side) of the insulation, you want it between the insulation and plasterboard. You can also get plasterboard with insulation already attached, a cheaper polystyrene version of this is available which might suit your needs and can simply be screwed to the battens.

 

[Peanut39]

Thanks for the advice. I thought about using insulated plasterboard but a bit expensive, will prob go with celotex etc. Interesting you say put polythene sheet on between plasterboard and celotex? What stops the damp penetrating the brick wall and saturating the celotex, (or which ever insulation)?
Kind regards

 

[ajrobb]

• Fix breather membrane behind the battens
  Fix 25mm x 40mm exterior timber to the walls (needs to be wider than 25mm) at 400mm centres
  fit mineral wool between battens held up with batten across top
  screw green MR plasterboard
  seal plasterboard with two coats of sealer or eggshell etc.

Putting polythene against the cold wall can cause condensation problems, soaking mineral wool and losing insulation benefit...

If you use celotex, put it behind the battens as a full layer. It is impervious to water. No need for polythene.

http://www.celotex.co.uk/Applications/Wall-Insulation/Solid-masonry-walls-Internal

 

[Peanut39]

Thanks for the advice. This is a new one on me so just to be sure;

1. Fit a breather membrane to the wall, (held up by screwing the exterrior timber to the walls). Is this same breather membrane as roofers use?
2. Mineral wool insulation in between timber.
3. Plasterboard.

OR

1. Celotex the entire wall, (top to toe).
2. Then 25x40mm timber, (when you say put celotex behind the battons do you mean wall, celotex, timber battons? (I guess with long enough screws to go through the timber and the celotex and into the wall)?
3. Plasterboard

Surprising how many different ways there is to do this. Want to get it right first time tho.

Cheers

 

[ajrobb]

Go to:
http://www.celotex.co.uk/Applications/Wall-Insulation/Solid-masonry-walls-Internal

Then fill out the forms to get the PDF instructions for Celotex

"Downloads for: Solid masonry walls (Internal)"