Optimum insulation for horizontal section of attic trusses (i.e. between truss tyes)?

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apple1

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Folks,
Quick query I hope someone can help with. About to begin insulating attic area. I will fit rigid insulation between dwarf stud walls and in sloping section of the trusses. At the top of the truss, i.e. the horizontal section which forms the 'ceiling' area, should I also fit rigid insulation between the 'tyes' or should I lay fibreglass above and between these sections.
The truss tye is 4" in depth. Thanks in advance, apple1
 
Re: Optimum insulation for horizontal section of attic trusses (i.e. between truss ty

its a better construction to carry your insulation from the eaves, up the slope, over the flat roof, and back down. if you do th sthen you can use the area behind the dwarf stud walls for storage etc without compromising the insulation envelope.

I would do this as follows:
1. quilted insulation at the eaves to ensure the cavity closer block is covered, always maintain 50mm air vent if its a 'cold' constructed roof.
2. At the moment, 130mm rigid PU insulation is needed to achieve this, so, depending on your truss size, put 100mm between truss and 'slab out' with 42.5 composite plasterboard.
3. Then i would incoroprate 100mm rigid between ceiling joists, slab out with 42.5 as ceiling AND incorporate 100mm quilted insulation over an ensure all gaps are filled.
 
Re: Optimum insulation for horizontal section of attic trusses (i.e. between truss ty

Thanks Syd..cost will dictate that I only fit rigid between the dwarf studs, up the slopes & across the horizontal section....though I do take your point about storage in the voids. The extra cost is significant at the moment as the roof is v large & even though I view insulation as an investment rather than a cost, it is hard keeping all balls in the air.
 
Re: Optimum insulation for horizontal section of attic trusses (i.e. between truss ty

but the actual area to be insulated, from 'eaves to flat' part, is less than 'section of flat, up stud, up sloped; area.....

think about it as a right angled triangle... i would insulate the hypotenuse whereas you want to insulate the other two sides, which have to be longer by geometry....

plus, the workmanship is less because you have 1 uniform construction on the slope, whereas your method would have 2 types...

remember, if you want to use quilted insulation on a flat ceiling part, you need on average 300mm of it.... therefore you generally then couldnt use the space behind the dwarf wall as storage with quilted insulation
 
Re: Optimum insulation for horizontal section of attic trusses (i.e. between truss ty

Syd....as usual, a wealth of knowledge, not to metion a dab hand @ numbers!
 
Re: Optimum insulation for horizontal section of attic trusses (i.e. between truss ty

apple1 said:
Syd....as usual, a wealth of knowledge, not to metion a dab hand @ numbers!
Click to expand...

if i cant count it on my fingers then im in trouble :D
 
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