insulating single skin utility room

[Katharine1471]

Basically we have a single skin brick utility room adjacent to kitchen ( 2 walls brick to waist height, one wall brick to full height) and then polycarbonate roof over the top. It's off the kitchen and houses the tumble dryer and washing machine. We're having the kitchen all re-done and to match the same units out there that is also all getting re-done.

Due to the constraints of fitting units in I have opted for following the advice another person suggested which I will be thinking about doing this on the two waist height walls:

'fit 25mm x 50mm treated battens to the wall, 25mm polystyrene insulation between. Plastic membrane, tape any joints then screw 12.5 plaster board. Leave a gap along the bottom.'

and on the floor to ceiling height wall will be opting for similar but with 50mm insulation. This wall has the oil filled radiator stood against it. This is all to be fitted above the DPC and then I'll just use some kind of skirting or something to finish off along the bottom to hide the gap from the above finishing and the floor.

I was planning on using DPM behind all the battens.

My questions are:

1) should I be using a breather membrane over the entire wall before the battens are fitted?

2) they said polystyrene insulation - could I use 25mm celotex/50mm celotex PIR board? .


Having also been doing some more research I've found this:

http://www.insulation-online.co.uk/celotex-pl4000-insulated-plasterboard-previously-pl3000.html

could I just use this attached straight to the single skin wall with no battens and be done with it? I can't seem to find anything about if that has an inbuilt vapour barrier and/or can be used on a single skin wall?

any advice would be welcome. We're intending to do one or the other options in the next couple of weeks.

Thanks

 

[noseall]

Do you intend leaving the roof as polycarb?

It will be a condensation nightmare if you do.

Your greatest enemy will be moisture from INSIDE the house and extreme cold outside. Leave the kitchen door open to the utility whilst cooking on a cold winters day and that roof will be dripping like a tap.

Your other suggestions may be ok but they are nowhere near up to reg's spec. You still run the risk of black mould particularly behind the units.

 

[Katharine1471]

Thanks for quick response.

It will remain polycarb for the foreseeable future. I have been reading lots of topics about insulating polycarb from inside also but i can see how that might could go wrong RE condensation also I imagine it'd have to be easily removable presumably as I imagine to turn translucent roof to opaque may have to get planning?

The kitchen is vented with extractor fan direct to outside and the utility has vents which are left open the entire time. It will be heated in colder weather but we've not yet had a need to do so yet (only been in house for 6 months)

the door between kitchen and utility is often closed although when open and cooking the couple of times it has steamed up has been when I've forgotten to turn the extractor on and when I then do it clears super quick so it is always on now if cooking (its an external spec door between kitchen and utility and is often closed anyway - i presume as requirement on the planning permission granted years ago when utility built)

Would it be better then to just do nothing?

there isn't any mould/damp issue currently in the existing cupboards installed out there.

when queried with some planners they said because it was a utility, separated by external rated door and the previous planning was granted then anything we do would be better than leaving it as it is already substandard and we're not claiming it is up to standard and we were not altering external (I didn't ask about the insulating roof!)

 

[tony1851]

There is a possibility here that you will cause more problems than you solve by trying to upgrade what is basically a sub-standard structure. It will also be cold whatever you do. Personally I'd leave well alone and save your money.

 

[Katharine1471]

if its specifically a problem of mould on the plasterboard would some kind of wooden tongue and groove cladding be a better option?

Its mostly the brick I want to hide to improve the appearance so would it be an option to just batten out and then clad avoiding all insulation altogether?