Fix insulated plasterboard to existing plasterboard

corman007

Hi,
Am in the process of decorating the box room in a timber frame 3 bed semi, the room gets a lot colder than the others and i would like to insulate it better. I took off some plasterboard on one of the exterior walls and found that the cavity has insulation in it covered by polythene.
I would like to install insulated plasterboard over the exisiting 12mm plasterboard and was wondering if this is a good idea or should i remove the existing plaster board first. Any help much appreciated.
James.

BryanF

corman007 wrote: »

Hi,
I took off some plasterboard on one of the exterior walls and found that the cavity has insulation in it covered by polythene.

James can you elaborate on this?

cavity block / hollow block ?

corman007

Hi Bryan,
I meant to say that i removed the plaster board on one of the exterior facing walls and the cavity between the wooden studs was filled with glasswool insulation see picture attached

• A) Plasterboard: an internal layer of plasterboard has excellent fire resistance and provides a smooth crack free surface for immediate decoration.
• Vapour Check: prevents moisture from within the house (steam from kitchens and bathrooms etc) reaching the insulation and timber structure.
• C) Structural Timber: the timber framed studs, normally 140mm deep x 38mm wide are usually at 600 centres, but in some cases may be 400 centres. The stud size depth may be increased to give a better thermal value (up to 220mm deep).
• D) Thermal Insulation: there are various non combustible products which may be used such as mineral wool, cellulose, hemp. sheep wool etc. The stud sizes can be increased to accommodate more insulation (up to 220mm deep).
• E) Sheathing Board: this board can be OSB (oriental strand board) or plywood. This strengthens the wall panel and supports the breather membrane.
• F) Breather Membrane: this is a water proof membrane fitted to the sheathing board outer frame keeping out moisture which may penetrate the porous concrete blocks or bricks but still allows air through for timbers to breathe.
• G) Wall Tiles: the timber frame is the main structure which supports the roof and the outer layer of block or brick is supported by the timber frame by fitting the stainless steel wall ties. They are flexible to allow for differential movement.
• H) Cavity: this is a clear 50mm wall cavity which provides a complete separation of the external wall from the highly insulated inside wall and helps prevent any moisture which may penetrate the porous bricks/blocks reaching the inside of the structure. This cavity must be drained and vented.
• I) Outer Cladding: the external cladding can be of many materials; most common are brick or rendered block work and is simply a protection for the timber frame. In many other countries Upvc, aluminium or timber are used.

BryanF

add staggered stud & mineral fibre and membrane totally sealed. Remove existing board and membrane first.

corman007

Thx for reply, no idea about building regs, ventilation etc but why would i remove existing plasterboard i was leaning that way anyway but is there a reason for it other than thats the way its done, what would happen if i didn't? should i use something like rockwoll and would something like 500 gauge polythene do?
Regards james

BryanF

corman007 wrote: »

Thx for reply, no idea about building regs, ventilation etc but why would i remove existing plasterboard i was leaning that way anyway but is there a reason for it other than thats the way its done,

1. what would happen if i didn't?
2. should i use something like rockwoll
3. and would something like 500 gauge polythene do?

Regards james

1. people will differ on this on this but Id remove the plasterboard to avoid any potential moisture becoming trapped at this location
2. yes (rockwool is a brand name for mineral wool or as you called it above glass wool)
3. things have move on from polythene. Some still use it, I wouldn't specify it. there are long lasting air-tightness / vapour control membranes, tapes and sealants on the market. if you are doing this, do it right and do every inch of the house, fully sealed, that means floor and wall junctions etc.

corman007

Thx Bryan, yes that what i want to do room by room its a shame i have to with a 7 year old house bt hey thats for another thread:mad:. Just a question on the plasterboard - would any insulated plasterboard do or are there specific types for instance would either of these be ok:
https://www.build4less.ie/product_info.php?cPath=946_1060&products_id=6938
http://www.onlineinsulation.ie/category.php?category_id=9&cat_name=InsulatedPlasterBoard

BryanF

i would stick with the mineral wool and avoid insulated plasterboard products due to timber frame construction

corman007

yeah it would save me alright my only worry is that the studs are 90mm deep would this be enough?