# Insulated plasterboard and its alternatives



## DTR (8 Apr 2014)

Evening all,

Sooner or later (probably later) we will be redecorating the dining room of our 1950s semi. The two outside walls are solid so I was thinking of boarding them some kind of insulation. I don't know much about what is available or how to use it, so I was hoping you kind folk could give me some pointers please. 

Some things that immediately spring to mind are...
What product do you recommend?
How do I fix it to the wall? (I've heard dot and dab isn't appropriate)
Do I need to leave an air gap behind it? 
Does there need to be any ventilation or a membrane of some sort?
There is a radiator on the larger wall; what do I attach the brackets to?

Thanks


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## chippy1970 (8 Apr 2014)

No need for any air gap , just use insulated plasterboard and dot & dab in a can if you've only got a few boards to fit. Just like expanding foam but it doesn't expand as much. You spray lines of it on the board wet the wall, then after a few minutes the board will be ready to fit.

You can use normal dot and dab adhesive too but the can stuff is less messy.

For fitting heavy objects just screw and plug into existing wall and use packing ie copper pipe cut to the depth of your plasterboard. That will stop you crushing the plasterboard

Sent from my HTC One using Tapatalk


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## RobinBHM (8 Apr 2014)

My understanding is that building control recommend using PIR foil backed insulation (celetex type), cover the wall without any gaps, tape joints with silver tape, then screw on 2 x 1 laid flat at suitable centres for plasterboard. When Ive done it, I fit additonal battens for rads. The advantage of doing it this way id that there are no thermal bridges. The silver backing acts as the vapour barrier -always recommended to be placed on the warm side.

Robin


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## Mark A (8 Apr 2014)

If you go down the polystyrene backed plasterboard route, don't use solvented adhesives (such as the green Gripfill) as it will dissolve the polystyrene.


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## hanser (9 Apr 2014)

Some sort of mechanical fixing is required to cover off fire risk. I've used screws/plugs for small areas - ie external bathroom walls. That worked but probably best to use proprietary fixings. These look good if expensive http://www.ebay.co.uk/itm/INSULATED-PLA ... 338cc9e8e3.


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## blackrodd (9 Apr 2014)

A few relevent questions please.
Are you hacking off any plaster on these outside walls? Are the walls damp?, 'Cos now is the time to get shot of it, Any picture rail?
Is there any cove fitted? how many sockets or radiators? can you get the skirting off without too much damage?
Are there any good dry liners or plasterers in you're area, as this is really a job for someone that has some trowel skills for the application and finishing, and would be very useful to have as a costing guide.
Try and get someone that is recommended by someone you know, The best AND the worst are both out there!
Measure up and get an idea of how many square metre's is required, in total.
Regards Rodders

Theres 2.88m sq in a 1200x2400 board R.


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## DTR (10 Apr 2014)

Thanks for the tips guys.



blackrodd":116girdd said:


> A few relevent questions please......


Are you hacking off any plaster on these outside walls? No
Are the walls damp? No.
Any picture rail? No.
Is there any cove fitted? Yes, of the polystyrene variety. The stuff I've already taken down didn't put up much of a fight.
how many sockets or radiators? No sockets, one rad.
can you get the skirting off without too much damage? Judging from the rest of the room, yes.
Are there any good dry liners or plasterers in you're area, as this is really a job for someone that has some trowel skills for the application and finishing, and would be very useful to have as a costing guide. I know a good plasterer, but alas, SWMBO wants us to do it ourselves :roll: .


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## MMUK (10 Apr 2014)

1950's semi? I assume this will be one of the Italian built jobs not long after the war if it's got no cavity. There's quite a few around here like that too.

As far as the poly backed p/board goes, you're fine to dab it on with drywall adhesive. No mechanical fixings are required.

Your other option is to space blanket the wall then batten it and fit normal p/board over that. You could even fit 25mm Celotex in between the battens to add extra insulation.


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## DTR (14 Apr 2014)

MMUK":3odmgzu4 said:


> 1950's semi? I assume this will be one of the Italian built jobs not long after the war if it's got no cavity. There's quite a few around here like that too.



The house was built in 57 so I'm not sure how Italian it is. The front wall is cavity and the sides and back are solid. But whoever built it, they left their plumb bob and spirit level at home that day... :roll:


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## DTR (19 May 2014)

Apologies for bumping the thread, but this project is now looming in the not-so-distant future. 

We are leaning towards the idea of fitting some 2x1 battens to the wall, then attaching the plasterboard to the battens. If this is acceptable, what is the best board to use? Several have been mentioned already but there doesn't seem to be a clear winner. 

Thanks once again.


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## RogerS (20 May 2014)

DTR":20syvmhe said:


> Apologies for bumping the thread, but this project is now looming in the not-so-distant future.
> 
> We are leaning towards the idea of fitting some 2x1 battens to the wall, then attaching the plasterboard to the battens. If this is acceptable, what is the best board to use? Several have been mentioned already but there doesn't seem to be a clear winner.
> 
> Thanks once again.



Don't forget to get either lots of tins of foam or fibreglass to stick in the inevitable small holes between the celotex/whatever and your battens otherwise you can get a cold spot.


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## david123 (21 May 2014)

About 12 years ago I started to line all my exterior walls (inside) with Kingspan Thermawall TW56. Initially I had to batten out the walls with 1 in.² timber and apply the thermaboard to that, after finishing off two rooms I ordered more, only to be told that the new stuff didn't need to be fixed to batons. As my walls had damp patches on them, I contacted the manufacturers and they confirmed that it would be okay to do this. 
As our house has 9 inch solid walls and wicked out the heat through them, the Thermawall made a tremendous difference and cut our heating bills quite considerably, and stopped the damp wicking in due to the osmosis effect.
Thermawall on the inside, plasterboard on the outside. Also buy the past that sticks them to the wall. Got that from the same place

8-4 sheets at that time (October 2002) cost £21.60 + VAT. Still performing well, best money we ever spent.

We got it from from Essex insulation 

Hope that helps


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## graduate_owner (26 May 2014)

I may be wrong here but I'm sure I read something about having to comply with building regs if you intend to insulate your walls - i.e you can't just put whatever thickness insulation you like, it has to have the required level of insulation. It may be worth checking this out before you proceed, or do it quietly without informing anyone. Or I may have dreamed it.

Also there could be an issue with dampness because of condensation (check out dew point in solid walls). It's all worth finding out before you start to avoid expensive mistakes.

K


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## galwayworker (27 May 2014)

This is a link to a PDF file from the Energy Saving Trust on Practical Refurbishment to Solid Wall Houses. Page 13 covers internal insulation and recomends a U value for the new insulation. Hope it helps.... 
http://www.lowcarbonhub.org/wp-content/ ... houses.pdf


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## DTR (27 May 2014)

Thank you all for the extra tips, I will give these a look over....


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