insulated plasterboard

doningtonphil

Hello


Posted before about the bungalow we have bought. Not much going for it energy efficiency wise - solid stone walls and 50% flat roof with unknown levels of insulation.


There are myriads of ways to insulate the house with internal or external wall insulation coming out on top in the EPC report that came with the house.


External isn't an option either cost wise or physically fitting it. So internal is the way to go.


My wifes uncle has been renovating their house over the last few years, each room he has done has had any plasterboard on outside walls replaced with insulated plaster board.


Our outside walls are obviously dry lined in some way. Does either replacing the existing plasterboard with insulated board or overlaying existing with insulated plasterboard make a significant difference to how well insulated the house will be?


Regarding ceilings. For various reasons we are putting false ceilings in, about 100mm below existing ceilings. Is there any value (or any danger) in putting either fiberglass 'loft'insulation or celotex insulation board above the new ceiling to help insulate the flat roof?


Hope you can help


Phil

phill99

If you are reducing the ceiling height by 100mm, then you can only get 100mm of insulation in there. 100mm of fibreglass insulation is the same as was required in lofts 30 years ago. It's now 270mm. Therefore to get benefit, you would be better removing the existing ceiling as well so that you can get as much insulation in there as possible.

The additional cost now will be minimal compared to the energy savings, especially as most heat is lost out of the roof.

Captain_Flack.

phill99 wrote: »

If you are reducing the ceiling height by 100mm, then you can only get 100mm of insulation in there. 100mm of fibreglass insulation is the same as was required in lofts 30 years ago. It's now 270mm. Therefore to get benefit, you would be better removing the existing ceiling as well so that you can get as much insulation in there as possible.

The additional cost now will be minimal compared to the energy savings, especially as most heat is lost out of the roof.

Or use celotex.

doningtonphil

Thanks for the replies.


Sounds like it is possible to do - celotex seems the way forward.


There is obviously some insulation above the existing ceiling but the EPC assumed it was minimal.


Would 'glueing' the celotex to the underside of the existing ceiling be an option?


Is there a risk of condensation?


What about the insulate plasterboard for the walls - on top of existing boarding - is that an option / allowed / worthwhile?

WestonDave

You'd need to look more into it because my knowledge is a bit vague having only seen it on a "green" house tour, but there is a product called "Marmox" which is an insulation board like celotex but has a face on it that can take a plaster skim. The idea being that rather than putting in insulation then plaster board and skimming over, you can have more depth of insulation using the depth that would have been taken by the plasterboard. The website is here - no connection to me other than coming across it - http://www.marmox.co.uk/products/marmox-waterproof-insulation-board

Captain_Flack.

doningtonphil wrote: »

Thanks for the replies.


Sounds like it is possible to do - celotex seems the way forward.


There is obviously some insulation above the existing ceiling but the EPC assumed it was minimal.


Would 'glueing' the celotex to the underside of the existing ceiling be an option?


Is there a risk of condensation?


What about the insulate plasterboard for the walls - on top of existing boarding - is that an option / allowed / worthwhile?

Go onto the celotex website and join up. You'll get help and support there.

You can screw the celotex up and board over. There are foil backed plaster boards to give you a membrane also insulated boards.

System

kingspan do one too "kooltherm" is the insulated plasterboard...
best job (imo) would be to take away whatever you have there put new rigid insulation between the rafters (leaving a 50mm air gap on the roof side, then put insualted plasterboard on the inside to whatever thickness you like

this pdf gives a good idea of the build ups and also the respective uvalues for the different thickness http://www.kingspaninsulation.co.uk/getattachment/78f5cba0-5188-4b8a-a9ec-a0708ccc61be/Kooltherm-K7-Pitched-Roof-Board.aspx

Leon_W

I used Gyproc Thermaline Plus 40mm to internally insulate all the exterior walls upstairs in our 3 bed detached and used 27mm on all the ceilings. Just overboarded the ceilings and ensured there was more conventional insulation above and dot and dabbed the 40mm to the walls with adhesive. Plaster coat to finish the job.


It was not cheap. The boards are pretty expensive but got a discount from some company on ebay. Was it worth it ? Absolutely ! The house is a lot lot easier to heat and has lost that constantly damp feel. Wish I'd bitten the bullet and done it a few years ago to be honest.

Details here
http://www.british-gypsum.com/products/gyproc-thermaline-plus




/

System

the only worry I would have about just insulating over the existing plasterboard is the danger of condensation forming on the old plasterboard unseen, if you were going down that route I would suggest getting a dew point calculation done by a manufacturer (used to be free!) to make sure

doningtonphil

Condensation has been my main concern. looking at the British Gypsum White book though, they indicate that as long as a continuous bead of adhesive goes around the perimeter of the new boards then condensation shouldn't be an issue.


I don't know how safe it would be to assume that directly above the ceiling plaster will be an insulating layer with a ventilated space above it. If that is the case, then overboarding the ceiling would be OK as well I assume.


Is there anything in the regs that should prevent me from doing what the_r has done?


Just realised one of my acquaintances on LinkedIn is a Commercial Manager for Knauf insulation so have sought his advice as well


THANKS FOR ALL THE FEEDBACK

MX5huggy

You will be paying a premium to have the insulation glued to the plasterboard, just buy insulation and plaster board and stick them up.