Kingspan or Glass Wool - Which is best for Floor Insulation

[dtl]

Hello,

We live in an old house with suspended ventilated wooden floors.
We intend to lift the floors and insulate from above.
We intend to use either 150mm glass wool suspended on chicken wire or 100mm kingspan suspended on batons.

We are not concerned with the difference between ease of fitting or the price difference between the two different methods.

We want to fit what what will work best and provide the best insulation.

One concern I have is that it may be hard to get a snug fit with Kingspan between what may be old wonky joists?

Any advice appreciated on what is the best way to go?

Thanks

James

 

[outlaw]

Hi James,
I have always hated (glass) insulation. As a builder, the invention of Kingspan has made my life a lot easier.
The wonky joist issue isnt really an issue, if all the floorboards are to be lifted, just lay the kingspan across the rather than along them, this will allow you to "chop it in" without wasting much. The other benefit of Kingspam is the thermal quality, unless you use Glass upto 250mm thick it will never out perform Kingspan, and only as long as it stays fluffy, it does sag after a few years.
A bit waffly I know but hope this helps.
Interesting ID by the way, do you shoot it?

Tony The Outlaw

 

[CHRIS]

One concern I have is that it may be hard to get a snug fit with Kingspan between what may be old wonky joists?

Thats where our old friend Mr Spray foam comes in!!!!!

The best way of getting a good fit is with a good spray foam gun (not a can with a nozzle) filling the gaps - it is nasty stuff if it goes mad. This is what I did with Celotex and it worked a treat.

Not in true PPUK spirit but works well, I think Breather paper and sheeps wool would be the most Eco way of doing it but Celotex is in a league of its own in terms of performance.

 

[AMc]

I think you'll find Celotex is in a league with ecotherm and kingspan all 3 (there are probably others) are rated to out perform 2x as much mineral wool as you are proposing.

Another vote to fill the gaps with foam, but my builders hate the gun based foam and insisted on spray cans with applicators - cheap as chips from screwfix. Don't go mad with it, as it does keep expanding for a while and over zealous application can lead to something that looks like a cut scene from Aliens - possibly messing up your subfloor ventilation or bridging the joists onto the subfloor.

 

[Schoolmarm]

Spray foam will stick to the wood and be impossible to remove though.

 

[CHRIS]

Spray foam will stick to the wood and be impossible to remove though.

Thats good isnt it!!!!

Just let it dry and then pick it off, dont try wiping when still tacky as it will cause a right mess - its a job that is underestimated and should be done by someone with some skill as it is very difficulty to get right. One of these sanding pads gets it off of doors etc when it has gone mad.

but my builders hate the gun based foam and insisted on spray cans with applicators

Is that because they are too lazy to clean the guns!!!! The spray cans cant be controlled as they are on or off but use the low expansion window fitting stuff with a gun for better results and much less waste. Also The Kingspan - celotex thing is very regional as in some areas we cant get one but tons of the other - in fact never the one we ask for, but I am sure it all comes from the same factory in Sudbury.

 

[dtl]

Thanks for the replies.

What is the tradename for the low expansion foam?

Thanks

 

[CHRIS]

I have used these geocel products

http://www.geocel.co.uk/prodrange.aspx?r=dgsp

 

[AMc]

Is that because they are too lazy to clean the guns!!!!

Shouldn't that have a question mark? It's because the guns clog all the time. They prefer the disposable ones but weren't using low expansion stuff, just standard 'no nonsense' foam from Screwfix. At the end of the day I'd prefer to buy a few more cans at £3.50 each than pay them £16-20 an hour to clean clogged guns which I'd also have to buy.

It did make me smile that the boss (hands off) wanted me to get the guns and cans but the actual guys doing the work specifically told me to get the all in one.

FWIW It is reversable, there is a foam remover which chemically destroys cured foam. I've had no reason to use it and I'm I'm more concerned about the performance and durability of my warm roof than removing foam from the rafters when it eventually needs to be redone in (hopefully) many many years time.