Insulating converted loft

David · 2011-09-09T17:40:03+00:00

Hello helpful people,I have a few questions regarding our converted loft which is currentlymy bedroom!Situation: No insulation between rafters at all, this makes the roomfeel very very cold in winter (drops to around 8=BAc in the cold). Thereis only a small amount of insulation under the floorboards between thejoists, it's extremely old and has turned black with dirt/dust. Thereis a 1.7kw radiator in the room which does heat the room to acomfortable temperature but an awful amount of heat is lost from theroof - snow melts quicker than any other house on the street.The ideal solution I am told is to remove all insulation betweenjoists, removed plasterboard which is covering the rafters andinsulate using Kingspan or Celotex boards and then fix the boards backon.However this will cause a lot of upheaval to the room which is notdesirable.I am thinking of a good compromise that could be made. In loft spacethere are storage compartments which can be accessed from doors in theloft like this: storage space looks like this inside: of the room (view from storage area) this picture here you can see: arrow points to a gap which can be accessed from all the storageareas.Would it be possible to slide some insulation board up these gaps toat least stop the heat loss from the main heated part of the loft?Would there be problems with damp?I hope you can visualise what I am talking about.Thanks

G

geraldthehamster 14 years ago

=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D\

=A0 =A0 =A0 =A0|

=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D/

I think if the insulation were cut as a snug fit, it would get stuck as you tried to push it up. Also there will be some variance in the gap between any two rafters. Either it will get stuck or you will have an air gap. If you can bite the bullet and pull the existing PB off, that's most of the mess out of the way in one session. I really would do this properly; we did ours to regs (then 5 inches deep) and the difference is phenominal. You'll thank yourself for doing it.

Cheers Richard

Vote

G

geraldthehamster 14 years ago

=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D\

=A0 =A0 =A0 =A0 =A0|

=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D/

Sorry, I don't mean an air gap. You want an air gap, in the traditional sense, behind the boards. I meant you'd get gaps between the boards and the joists, creating cold spots and the potential for condensation.

Cheers Richard

Vote

G

george [dicegeorge] 14 years ago

if the room underneath is inhabited then you dont have to insulate the floor.

easiest could be to stick kingspan or celotex to the inside of the walls or ceilings, using long screws of pink dryfix foam, then stick plasterboard to that.

But you'd lose 6 inches.

[g]

Vote

G

geraldthehamster 14 years ago

As I think someone has already mentioned, insulation in the floor of a loft conversion is there for fire prevention. I believe this is a building regs requirement for new conversions above the first floor.

Cheers Richard

Vote

J

John Rumm 14 years ago

I agree, in the sense that yes doing it without the original PB in place will be easier and more effective. I was just highlighting that with the insulation in contact with the back of the exiting PB, there will be little scope for the kind of drafts that would render the insulation ineffective, since the only air available will be that in the actual gaps etc. You will get the cold bridging of the joists thought.

I think the order of preference (in terms of results and quality of job) would be to:

1) strip the existing PB, insulate between and under the rafters, then re board. 2) Dry line under the existing PB, or 3) attempt to retro fit insulation behind the exiting PB.

Only do 2 if you really can't face 1, and only do 3 if you really can't afford the loss of headroom from 2!

Vote

R

RobertL 14 years ago

There are heaps of other building control requirements for loft conversions creating habitable rooms. This sounds like a very 'informal' conversion.

Robert

Vote

D

David 14 years ago

=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D\

=A0 =A0 =A0 =A0|

=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D/

To be honest, I would love to strip the whole room, properly fit insulation etc but it's just not feasible, option 2 would cause a loss of headroom and that would not be very good seeing as I can *just* stand upright without touching the ceiling. Anyway, just to confirm, will this board be okay and can I insulate the walls too?

formatting link

Vote

J

John Rumm 14 years ago

the right sort of stuff.

Vote

D

David 14 years ago

=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D\

=A0 =A0 =A0 =A0|

=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D/

Can I ask where you bought yours from? The price shown on the SF website is for 5 boards but minimum order is 10.

Vote

D

David 14 years ago

:

=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D\

=A0 =A0 =A0 =A0 =A0|

=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D/

Actually BnQ have quite a variety at what seems to be a good price. Also the depth of the rafters is 80mm, would 60mm insulation cause any damp?

formatting link

Vote

J

John Rumm 14 years ago

APCO Insulation in Benfleet Essex.

8x4' sheets of 50mm were (at the time) £12 for seconds, and £14 for new. Discount on top of that for quantity.

Contact:

APCO Insulation,

77 Stanway Road, Benfleet, Essex,

01268 565 055

That's mostly polystyrene rather than PIR foam - a bit over only half the insulation value for the depth...

As long as air can flow then you should be ok.

Vote

H

Hugo Nebula 14 years ago

Regulations April 2002". This may have been true for loft conversions (but not new-builds) then, but the requirements of Part L have changed twice since then, including the renovation of thermal elements which have to be upgraded to a maximum U-value of 0.18W/m^2K; it certainly won't comply for any work you intended to carry out today.

Vote

G

gremlin_95 14 years ago

Thanks for the information, I am still on the look out for insulation at a cheaper price anyway.

Vote

Insulating converted loft

Join the Discussion

Didn't find your answer?