Insulating roof voids??

[dinger541]

Ok folks.... I know nuthin... I admit that.... hence i need help.. PLLLEEEZZE

Question One: I've got a dorma roof with triangular voids, the outer (angled edge) the roof and the inner vertical the outer wall of the bedrooms front and back. I need to insulate in the void... the question is do i put insulation on the roof (angle) side of the triangle or the the ceiling (base) and bedroom wall (vertical edge of the triangle)?

Question two: The ceiling voids between the downstairs rooms and the upstairs rooms has access from both dorma triangular voids front and back, can i fill this (or actually place a layer of insulation along the void) or can i just complete the inner and base of the triangle and effectivly seal off the ceiling voids, negating the use of insulation but at the same time stopping any airflow through this space??

Sorry about the descriptions as opposed to drawings folks but im a computer ludite, any help will be appreciated...

Cheers

Dinger

 

[masona]

You can insulate the roof area how you like but the most important thing is you must have a 50mm air flow at the back of the roof rafter and at top to allow continual circulation of air.Also do not cover any soffit vent round the edge.

 

[dinger541]

thanx Masona,

Just one question im still unclear about. The ceiling voids, can i fill these with insulation, I'll maintain the airgap through the eaves up to the loft but there will be no flow along the present ceiling void...will this cause a problem...

By the way Merry Christmas

Dinger

 

[masona]

Air flow helps timber to breathe and stop any condension from the roof area.Without seeing your layout you could leave a gap on each end of the ceiling for air circulation or air brick vent on the outside wall instead.You can go further by adding ridge tile air vent or roof tile air vent which you can cut out a hole in the roofing felt (inside carefully cut out a triangle shape and bend it to the top and sides beneath the tile,so any broken tiles above will collect the rain and will miss the hole via to the gutter below).

The picture on the right have a connection for plastic flexible hose if needed,but don't come with it as shown.

 

[DIYnot]

Dinger, here is the link to your diagram:

Diagram for roof voids (word document)

 

[masona]

The area you're worried about,you can put in a off-cut gutter downpipe or soil vent plastic 110mm pipe or whatever approx 300-400mm long thru' the red line area in each centre of the joists,so the insulation materials resting on the pipe to protect the air-flow to vent out to soffit area.

 

[dinger541]

Masona and William,

William thanx for the help with the pics (as Breezer says a pic is worth a thousand words) and Masona thanx for the info m8.

I'll put an off cut of down pipe from the eaves into the ceiling void as youve indicated. I have a massive problem with draught, gale force cos of the wind and the position of the house in relation to the prevailing winds up here. This should insulate the majority of the house whilst stil allowing airflow along the voids. I just wasnt sure if this was needed or not.

Thank you both and have a good new year.....

Dinger