Raised Insulation off joists in extension

blueskys

Hi all
Is there any reason for insulation (mineral wool) being raised off the ceiling (gyprock) in a one story extension with a pitched roof? The extension has always been a bit cold, it vented with sofit vents which nearly give too much ventilation. so i opened up the ceiling to have a look and a lot of the insulation is hanging over the joists held up with assorted lenghts of wood rather than being between them. The house and extension is timber framed with block on the outside.
I want to put more insulation on the top so just wondering what the reason for this is, as i can't imagine it is for airflow?
Thanks

Outkast_IRE

blueskys wrote: »

Hi all
Is there any reason for insulation (mineral wool) being raised off the ceiling (gyprock) in a one story extension with a pitched roof? The extension has always been a bit cold, it vented with sofit vents which nearly give too much ventilation. so i opened up the ceiling to have a look and a lot of the insulation is hanging over the joists held up with assorted lenghts of wood rather than being between them. The house and extension is timber framed with block on the outside.
I want to put more insulation on the top so just wondering what the reason for this is, as i can't imagine it is for airflow?
Thanks

You need to maintain the airflow above the insulation. There should be a space between the insulation and the inside of the flatroof so air can flow and help prevent the buildup of condensation etc.

There are plenty of flatroofs out there that have been destroyed by being insulated incorrectly under them.

See one example of many here.

http://build-x.info/img/409/Insulation-Page4127.jpg

blueskys

Cheers i understand about the airflow above the insulation but
there is a gap between the insulation and the ceiling underneath it which is
puzzling me, just wondering what the reason for that is.
Ps it is not a flat roof, its a pitched roof with maybe 3-4 ft space above the insulation
which as i said is mostly laid on top of the joists

Steve

Can't think of any sane reason for that other than the original builder left on a horse rather than in a van... I assume the ceiling board is foil back or moisture proof.?

blueskys

Ya that's the conclusion i came to, the lengths of wood are placed haphazardly over the joists so its like they just threw the insulation on top of it. Makes the most sense to be honest.

Outkast_IRE

blueskys wrote: »

Ya that's the conclusion i came to, the lengths of wood are placed haphazardly over the joists so its like they just threw the insulation on top of it. Makes the most sense to be honest.

Sorry I misunderstood you initially. Yeah it sounds like they may of taken a lazy route to get the insulation up before putting the plasterboard up. Its certainly far from ideal to have an air gap between the celing plasterboard and the insulation.