Which type of internal wall insulation?

[dan_aka_jack]

Before this Winter, I want to install some interior solid wall insulation on the exterior wall in our living room.  It's a very long wall and I suspect the very poor insulating properties of this wall are the primary reason why the living room takes such a huge amount of energy to keep warm during the winter.

We don't have any wall cavities so cavity wall insulation is out of the question and exterior wall insulation is Too Damn Expensive and Too Tricky for my modest DIY skills.  So I'd like to install some interior wall insulation.

The room is reasonable large so we can, if needs be, use some quite deep insulation.  My main criteria is: which type of insulation provides the largest decrease in thermal conductivity per £ spent?  Should I simply screw Kingspan onto the walls and do a plaster render over the Kingspan? Or should I build a 250mm-deep wooden stud frame, filling the frame with loft insulation and then putting plasterboard over the stud frame?

Searching the 'net for some figures... it looks like Kingspan Kooltherm K17 Insulated Dry-lining Board has a thermal conductivity of 0.024 W/m.K (insulant thickness 15–24 mm), 0.023 W/m.K (insulant thickness 25–44 mm) and 0.021 W/m.K (insulant thickness ≥ 45 mm) whilst 250mm of loft insulation has a thermal conductivity of 0.040 W/mk (but I'm not sure I believe that figure) so it sounds like Kingspan is a significantly better insulator than 250mm of loft insulation.

And do I have to worry about condensation building up?

Any advice would be great!
Thanks,
Jack

[rhys]

For most drylining Kingspan is the way to go. You can "glue" to walls with the right dabs of adhesive and the use long frame anchors  a couple per board, the hold the panels back,  all as Kingspans guidance notes on their web pages.
Kingspan is vapour impermeable so interstitial condensation should not be a problem, provided bathrooms and kitchens are vented as they should be. You can also finish the boards with a surface "slurry" that acts as another vapour barrier, if you want to. I'd avoid wet plaster, easier and quicker to "tape and joint" the boards. Kingspan is relatively expensive, but much easier than studding out.
See my blog for details of what I did.

[MR GUS]

 go look at celotex website, I think it might be a bit better, & it has regs approval documentation which the others didn't have last time I bought some! (told that at the builders merchants)

[dhaslam]

B

Searching the 'net for some figures... it looks like Kingspan Kooltherm K17 Insulated Dry-lining Board has a thermal conductivity of 0.024 W/m.K (insulant thickness 15–24 mm), 0.023 W/m.K (insulant thickness 25–44 mm) and 0.021 W/m.K (insulant thickness ≥ 45 mm) whilst 250mm of loft insulation has a thermal conductivity of 0.040 W/mk (but I'm not sure I believe that figure) so it sounds like Kingspan is a significantly better insulator than 250mm of loft insulation.

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I think that the figures refer to a metre thickness of the insulation materials.  The dense material has about double the insulation value of fibreglass.   The sort of values you need are in the range of .1 to .2.  For this you need 110 to 220 mm of the dense stuff.   For example if you have 100 square metres of outside wall and a temperature differential of 10 C you only need 100 to 200 watts heat input.     The important part is around doors and windows where the high density materials have a big advantage.  Otherwise I would go by price.

[CeeBee]

I think that the figures refer to a metre thickness of the insulation materials...

Yes - one certainly has to be very careful with the units here to avoid incorrect answers.

Formally, 'thermal conductivity' is measured in watts per square meter per (Kelvin per meter), hence (cancelling out the meters) W/(mK). This is a property of the material itself - not of any particular amount of the material. If you like, its the rate of transmission of energy though a square meter of the stuff, one meter thick, with a one degree temperature difference between the sides.

Presumably Kingspan give different (but very similar) figures for the thermal conductivity of their materal depending on thickness because the material is 'composite' (not sure whether it is or not?), or because whatever happens at the surface has more effect when it's thinner.

The U-value on the other hand reflects the rate of loss through an actual piece of stuff of given thickness. Its units are watts per square meter per Kelvin (note not the same as thermal conductivity above).

To (simplistically) get from thermal conductivity to U value, you'd divide the thermal conductivity by the thickness of the material in meters.

So (to take Dan's 250mm loft insulation example): if the material has a thermal conductivity of 0.040, then 250mm of it will have a U-value of 0.160 (units as above - if you start using centimeters, fahrenheit, whatever, then make allowance as appropriate).

For the same thickness, indeed the Kingspan seems to get getting on for twice as good as fibreglass. Hence less thickness of Kingspan needed for same effect.

[rhys]

 go look at celotex website, I think it might be a bit better, & it has regs approval documentation which the others didn't have last time I bought some! (told that at the builders merchants)

Celotex is a perfectly good material but is a PIR insulation material with a slightly lower performance for any given thickness.
Celotex is usually used between battens on solid walls, which obviously gives cold bridges, unless cross battened, and then the cavity will improve the thermal performance.
Celotex as far as I know is not available as a laminated drylining material which is what Kingspan K17 is, so the cost of timber plasterboarding and additional labour needs to be added.
Kingspan is a Phenolic Foam insulation, which apart fromSpacetherm, has the best insulation value. of .21 -.24 W/mK
For a comparison of insulation performance see this link:
http://www.wbs-ltd.co.uk/newbuild_components_insulants.htm
BTW - both Kingspan and Celotex have all the Building Reg approvals, standards, Low Ozone depletion, etc that you could possibly want, Builders Merchants tend to stock sheets of Celotex as standard, which is why they like to sell it rather than order laminated products like K17, pick your merchant carefully, the mark up on insulation materials is at least 40%!! in many cases.

[MR GUS]

..sORRY I keep saying celotex, but actually mean xtratherm.
got any idea about that one?

additional...

 www.xtratherm.com
tel 0871 222 1033
 Their guides for newbuild, renovation etc are the clearest I've come across very good site for info gathering (eg stone wall requirements)

Gus

[dan_aka_jack]

This is all very good information, thanks loads.

So, just to make sure I'm not missing anything... please can I confirm that this would be the correct way to use Kingspan K17 (insulated dry-lining plasterboard for plaster dab / adhesive bonding):

1) Remove existing skirting board and mains sockets and clean the wall
2) Stick the Kingspan directly onto the existing wall (which is a "finished" wall i.e. it's been plastered and painted).
3) Tape up the gaps between the Kingspan boards
4) Install the mains sockets in the Kingspan
5) Paint
6) Add a skirting board
7) Done!

Is that roughly correct?  Do I have to remove the existing paint and plaster before attaching the Kingspan?

Thanks again for all the excellent advice!

[rhys]

..sORRY I keep saying celotex, but actually mean xtratherm.
got any idea about that one?

additional...

 www.xtratherm.com
tel 0871 222 1033
 Their guides for newbuild, renovation etc are the clearest I've come across very good site for info gathering (eg stone wall requirements)

Gus

HI Gus
Havent come across Xtratherm looks good, but their dryling product is again PIR which is slighly less effective compared to Phenolic, not much in it though. Strangly they do do a Phenolic Foam but not in laminate like Kingspan do strange, must be how their laminating factories are set up.
I guess if thickness is not critiacal it all comes down to price.

[rhys]

This is all very good information, thanks loads.

So, just to make sure I'm not missing anything... please can I confirm that this would be the correct way to use Kingspan K17 (insulated dry-lining plasterboard for plaster dab / adhesive bonding):

1) Remove existing skirting board and mains sockets and clean the wall
2) Stick the Kingspan directly onto the existing wall (which is a "finished" wall i.e. it's been plastered and painted).
3) Tape up the gaps between the Kingspan boards
4) Install the mains sockets in the Kingspan
5) Paint
6) Add a skirting board
7) Done!

Is that roughly correct?  Do I have to remove the existing paint and plaster before attaching the Kingspan?

Thanks again for all the excellent advice!

1 yes
2 Depends how sound the plaster is mine was ok'ish but very thick so I removed it saving 30mm on the room. Think I'd check how well the adhesive sticks to the paint, if the paint is vinyl matt or satin I'd either remove or at least score it and scratch through to the plaster. You don't want the paint to act as a vapour barrier on cold side of insulation. Bit picky 'cos not much moist air is going to get through anyway. Scoring will help the dabs stick.
Make sure there is a ribbon of adhesive around the edge of the boards to stop any air getting behind - very important this. I also foamed up any gaps at the tops and bottoms of the board with an intumescent foam ( same price as ordinary expanding foam)  to make sure.
Don't forget the mechanical fixings  i.e long frame anchors. They are to hold back the boads both whicle the adhesive sets and to hold the boards in place in case of fire.
3.Yep then when filled get your palm sander out unless your very good at tapeing and jointing
4. If you run any wiring actually in the insulation it should in theory be rated correctly. Also ribbon of adhesive aroud the boxes, I avoided this by relocating sockets on adjacent internal walls.
5.6.7 Yes done!!
Oh and one other point, work to an element of a building thant affects its thermal performance under Part L of the building regs needs a building notice. 
But... I coudn't possibly comment.
A good reason for notifying though is that you can later prove,you've done it properly, when you come to sell. There's a lot of C*ap dryling out there, that could put off a buyer, also you can prove to a Hip's home energy rating surveyor that there is added insulation, without it they must assume the insulation to the wall, based on the age of the property.

[MR GUS]

Why does anyone still use plasterboard these days?
...ok Hardyboard may be a bit more expensive but far more durable than P/board, & less nasties, no hazardous reclamation, can be ground down, not to mention tougher, water resistant etc.
 

 www.jameshardie.com


HardieBacker™ 500 Cement Board for walls and floors delivers superior protection against moisture damage and mold growth. It contains no paper facing, which serves as a food source for mold, or gypsum, which can disintegrate with continuous moisture exposure. HardieBacker board is an ideal choice for wet area walls; its smooth surface may be painted, textured, wallpapered, or tiled. HardieBacker™ 500 board is available in a 3´x 5´ and 4´x 8´ sheet size and is backed by a limited lifetime product warranty.

Thickness: 0.42"
Weight: 2.6 lbs./sq. ft.

3' x 5'4' x 8'

Mold ResistanceHardieBacker products achieve a perfect score on both industry standard mold tests. HardieBacker board scores a 0 (best possible score) on the ASTM G21 for mold resistance and a 10 (best possible score) on the ASTM D3273 test against mold growth.


Non-CombustibilityHardieBacker™ cement board is recognized for use in non-combustible construction in NER-405.

Surface Burning CharacteristicsWhen tested in accordance with ASTM test method E-84:

Flame Spread
Fuel Contributed
Smoke Developed  0
0
5 

Thermal Resistance(Approximate value) 1/4'' thick: R:0.13


 Hardyboard sidings on houses in fire zones (forset fires) are the only ones in burn zones that really have a chance of surviving compared to a regular home! ..something to consider if you live in a nice tree filled setting

[rhys]

Well you answered your own question it is very expensive.
I use Fermacell in limited areas i.e bathrooms when there's a need for fitting disabled rails etc. cheaper than the layer of ply most builders use.
Not easily available in an insulated laminate, although I expect Proctors would do it if you asked, they'll laminate anything to anything if you order enough sq. metres.
Now if you really what to spend money on an expensive durable insulated thin dry- lining material here it is:-
http://www.spacetherm.com/spacetherm-f.htm - Just add the gold plate for that very rich client.

[GW]

I am looking into this for my own house and have read this with interest, however I do not have the luxury of losing room space to fit internal insulation.  Has anyone considered the "Superfoil" insulation SF19 and would this be an option?

Graham

[MR GUS]

Well if you local friendly builders merchant is O.O.S. get them to write you an advantageous price & show it to your nearest topps tiles to match, with the sales guys name & no for "verification" ..that's how it's done  (cheap) whilst standing by the pile of backer board.

[billi]

Me  personally prefer organic based inside insulation  ... not that iam only wearing woolen socks , but i like breathing    materials

There is a woodfiberbased insulation board and adequate plasters ( more lime or clay based ) 

like this http://www.conluto.de/conluto-System.46.0.html


Or similar   


http://www.pavatex.co.uk/herstellung.aspx

Billi