Attic Insulation/Roof Insulation

Ponder013

Is there a difference between insulating the attic along the rafters and insulating the roof, between the roof joists?

I'll be insulating my small three bed semi pretty soon and want to use the attic for storage, but if I use the 300m reccomended, my storage will be restriced a lot, as will access to the attic - so I was thinking I could insulated between the rafters (150m), and under the tiles on the roof (200m) and board over for storage.

i have a feeling that there might be a problem with this though... it can't be that simple. What do ye think?

endasmail

from what i can gather from your post

insulate the joists with as much as u can fit in there and then floor it out with with OSB flooring or what ever

and insulate between the rafters ,leaving a 2" airflow
so if space is 200mm put in 150 mm insulation
would recommend kingspan for the rafters

dohertykkwdpd

Insulating between the roof joists mean that your radiators will be heating the room below the attic and the attic space above, as heat travels through plasterboard easily. This may be useful when storing items that need constant temperatures, and stops any pipes in your attic freezing! However the cost of this is much more because of the bigger space to be heated. I would recommend following the advice of the last poster, and remember to put a smoke alarm up there too.

gsxr1

Your attic is a cold area.

There is no point insulating the rafters unless you intend to use the room ie an attic conversion.

You will loss a fortunes worth of heat from your home.

You should build a platform or deck up there to use a storage and insulate the joists only. It
does not have to be pretty.
300mm is the way to go.

Buford T Justice

If you want to put flooring in, then it might be an idea to use insulated floorboards on top of the joists instead of osb, which will give you better insulation between the floors.

gsxr1

Fingers McGee wrote: »

If you want to put flooring in, then it might be an idea to use insulated floorboards on top of the joists instead of osb, which will give you better insulation between the floors.

can ye put 100mm PU board down and ply on top?

darraghsherwin

Hi,

I just finished an insulation project in my small 3 bed semi, I too wanted storage space and to insulate the attic.
I looked at insulating between the rafters but the insulation for insulating between the rafters has an R-value of around 3.85 and if I insulated with 300mm fibreglass, I would achieve an R-value of 6.5-7.
In the end, I choose to insulated with 100mm fibreglass (R-value 2.25) under 7sq. m of loft boards and insulate the rest of the of the attic with 300mm (R-value 6.85) in a U-shape around the storage area to match the external walls.
Had I know B&Q has insulated timber loft boards which have an R-value of 3.85 before I started I would have used these for the storage area instead of using fibreglass under the loft boards.

Hope this helps
Darragh

WildOscar

gsxr1 wrote: »

can ye put 100mm PU board down and ply on top?

Is PU board that white board that is on top of the attic door and around tank?

gsxr1

WildOscar wrote: »

Is PU board that white board that is on top of the attic door and around tank?

no. I think you are taking about airo board which is soft.

PU board is Kingspan or quinntherm

Ponder013

Thanks Darragh,

You seem to have found the happy medium there. I'd be interested to know if you experience any cold spots under the storage area.

This seems like an excellent idea, thanks for the tip about B&Q too, I'll be checking out thier insulation products.