Warm pitched roof

[ProDave]

45 minutes ago, Rishard said:

@ProDave Did your frame therm come in slabs or on the roll? Did you need to make these shorter lengths to handle or could you put up large sections in one? Did it require any temporary support before you put the osb up? Good to know there is an alternative way if I decide to insulate from below. I’m also using Knauf as I find it much nicer to handle. I’m using 150mm Knauf batts in my cavity so I can also use up some of my remaining bits of insulation for between my rafters. 

Mine was on the roll.  Most of my joists were at 400mm centres so a roll cut into 3 (cut it with a panel saw while still rolled up and bagged) each strip was a little too wide for the gap so it squashed in and stayed nicely.  Before I started on the roof, I did a test strip, and left it open and un supported for 6 months.  It did not fall out or slump.

 

I used the 100mm thick, 2 layers of it.  Measure length and cut to length on the ground then push it in at the top working down.  Most of it was done on my own.

[Ben1984]

What's the benefit/reason for the OSB under the rafters? Is this a structural element?

[ProDave]

24 minutes ago, Ben1984 said:

What's the benefit/reason for the OSB under the rafters? Is this a structural element?

In my case it's the racking layer.  Above the rafters is 100mm wood fibre, membrane, counter battens, battens and tiles.

[Rishard]

Likewise with mine. It’s a racking layer. Not required where I am but it only cost me £400 for the osb. If I’m able to osb the underside first, it’ll give me a great base to snug the mineral wool into. I can then tape my vcl to it from below as it’ll be a good flat surface to work with without having any bulges from the mineral wool. 

[Oz07]

Stupid question but when doing these warm roofs what is the process for the top layer with insulation. Are you covering the whole roof first then putting up your long battens inline with the rafters then nailing your cross battens ontop. I just envisage trying to climb around a pitched roof with no battens to climb on

[ProDave]

2 hours ago, Oz07 said:

I just envisage trying to climb around a pitched roof with no battens to climb on

I started fitting the battens from the bottom, making their own ladder as you went.

[Oz07]

22 hours ago, ProDave said:

I started fitting the battens from the bottom, making their own ladder as you went.

Am I being dense? Surely you have to cover the whole roof in osb or something first. Easy enough nail on some temp battens as you go up. Then cover in pir or woodfibre. Less easy but can still invisage. Then you've got to felt and batten inline with rafters? How to do this in 1 go? Unless your battens inline with the rafters are only 1m long or whatever width a roll of felt is. Final battens for tiling easy as standard.