insulation , holy cow bat man.

[robgil]

i simply cannot afford to fork out over 600 quid on 150mm kingspan. i still need to insulate though. its a lean to kitchen and bathroom , single glazed , clay lump with 150mm rafters.
are there any alternatives to insulation boards? i doubt fibreglass would have the same values as kingspan etc but would it be enough to keep me toasty in winter?

 

[Penners]

I'm not familiar with Kingspan prices, but do you know about these people, who sell second-quality? They might be cheaper.

http://www.economicinsulation.com/

http://seconds.co.uk/

http://www.secondsandco.co.uk/

 

[Flyfisher]

You'd think it would be possible to use an environmentally-benign waste-product like sheeps wool. Oh yes, you can, but funnily enough it's suddenly become really expensive. That's the green economy for you.

 

[Penners]

Rat fleece is pretty cheap around here. Buyer collects.

 

[robgil]

cheers guys , ive called seconds dot com and am awaiting a response.
i also called kingspan and apparently i need thermapitch. they told me if i was to do it as according to regs i would need 150mm but the minimum i can get away with without it being a bit pointless is 100mm. so , if kingspan say i can get away with 100mm why do the regs say i need 150mm minimum?
anyhow , i looked at sheeps wool and the price was indeed silly ,it may work out cheaper just to buy a bulk load of woolly jumpers and shove them in the roof.
ive also looked into recycled paper but i have no idea about how to calculate the depth of any insulating material and as i am governed to 150mil max by my rafters i dont want to put say 150mil sheeps wool in there only to find out ive wasted my money and needed a minimum of 200mil to make it work.
i have recalculated though with 100mil thermapitch just to see how much it would cost and it came to 325 quid without shopping around.

 

[skier-hughes]

Have you tried different makes?
I used http://www.ecotherm.co.uk/ to make my insulated room for the buffer tank. Far cheaper than Kingspan, though unsure if it is vastly different in insulating qualities

 

[AMc]

i also called kingspan and apparently i need thermapitch. they told me if i was to do it as according to regs i would need 150mm but the minimum i can get away with without it being a bit pointless is 100mm. so , if kingspan say i can get away with 100mm why do the regs say i need 150mm minimum?

If you can imagine a heated room wrapped in an infinite amount of insulation then no heat would escape but obviously you'd spend more on insulation than you would save in heating.

The cost vs. benefit balance of insulation goes up as the insulation gets thicker. Less than 50mm is the minimum you can install to see any real effect. 100mm isn't twice as effective as 50mm but it's still a substantial improvement. 150mm is roughly equivalent to 270mm of fibreglass which is what the regs are based on for a roof, it's not 3x as effective as 50mm but it's where the balance starts to shift. That's balancing the cost of the insulation against the pay back period of lower bills. Boards are more effective so you can use less but they cost more.

Seriously I wouldn't consider skimping on this, put in what you can fit as the cost of doing this again will be massive. If you underinsulate that room will be cold forever. If you put as much insulation in there as you can sensibly fit it will pay back in lower bills in a very short time.

Ecotherm was what my underfloor heating guy recommended over kingspan or celotex - higher density IIRC.

£600 is a lot. I only spent a bit more than that to cover a massive floor at 100mm. How much do you need and where did you get the quote. I used Sheffield Insulation who were substantially cheaper than the chain builders merchants. There is nothing to stop you doubling up 70mm or 3x50mm if it makes a difference. As long as you foam the edges to get a good seal the performance will be similar.

 

[Penners]

if kingspan say i can get away with 100mm why do the regs say i need 150mm minimum?

Because the regs want you to have effective insulation.

If you have room for, and the money for, 150mm then - as AMc says - fit 150mm. I quite agree with him that you should try not to skimp. Whatever money you save now will be lost (probably many times over) through wasted heat in the future.

But if you can't squeeze in more than 100mm, then you're stuck with that. It won't be as effective at keeping your room warm as 150mm, but it will still be much better than nothing.

 

[christianb]

As suggested before and followed up on, Seconds + co have saved me a pile of cash in the past. And that's emphatically NOT just giving them free publicity.

As for the issue of 100mm and 150mm... The regs also state that you should have a minimun 50mm air gap between the top of your insulation and the breather felt. This would mean having rafters 8 inches deep at the least (which would be OTT in the majority of cases).

So, why not use your 100mm between the rafters, and then underline with more foil board (which gives you a vapour check built in) or something like a thermal plasterboard?

Job done.

C.

 

[robgil]

i was going to use reed then lime plaster onto that but as i understand it fire regs would mean putting on a really thick coat of plaster. i also considered 175 mil rafters but even 150 mil rafters seems like overkill , the original rafters were much much smaller. economicinsulation quoted me 203 quid for 30 sq meters of 100 mil celotex , the u value of which is,
U-value, Combined Method : 0.24 W/m²K
(upper/lower limit 4.207 / 3.980 m²K/W, dUf 0.0000, dUg 0.0062, dUp0.0000, dUr0.0000, dUrc0.0000)
not sure what all that means.
thermal plasterboard? is it any good? i cant really come below the rafters too much as the lower part of the roof on the external wall sits close to the window as the walls are not very high and it would be difficult to finish it and still make it look ok, it might look odd if the ceiling butts up to the top of the kitchen window frame.

 

[AMc]

According to my records last year I paid £24.16 ex VAT a sheet for 100mm ecotherm when I was insulating the floor.
Most of our recent renovation is covered in thermal plasterboard I used Thermaline super phonolic £38.86 ex VAT a sheet 60mm overall (50 insulation and 10mm plasterboard.
The if you combine 100mm between the rafters and then 50mm+10mm thermaline (or similar) you will have a very air tight highly insulated ceiling.
Detailing around the windows is tricky when you internally insulate, if you are replacing the roof can you find the extra 50mm on the wall height?

 

[vicky whitworth]

I think my question might be related to this thread...
Please could someone explain to me about solid board insulation. What is it called? Is it all the same? What is Kingspan? What is Celotex? Does it come in different widths? And what would people recommend as the best for insulation properties but no more than 30-50mm deep (cos that's all the space I have)?
Thank you kindly.

 

[Penners]

"Board" (sometimes called "batt") insulation is a material called phenolic foam. It's not unlike the blocks of expanded polystyrene that are often used to pack delicate products, although it's a great deal stronger. Kingspan and Celotex are probably the two best-known brands.

The material comes in many different thicknesses and board sizes. For example, have a look at this page: http://www.just-insulation.com/eshop_celotex_rigid_insulation_boards_PIR_multi-purpose.html

To the best of my (amateur and not very extensive) knowledge, this type of product has the best thermal insulation capabilities of any material, provided it is properly fitted. It is easily cut with a hand saw.

I hope that helps.

 

[robgil]

i need to put the ceiling directly onto my rafters so it looks like 100 mil cellotex will have to do , or 150 if i can afford it. the walls wont be insulated and its single glazed but i can always invest in a new woolly jumper i guess.
if i use 150 mil it will be right up against the felt , this wont cause any problems will it? ive counter battened the roof.