They one they have advise is only 15mm, so that means insulation is only 2.5mm thick? as pb is 12.5mm thick. not sure how the two product compare in U value i.e between PIR and wool insulation?
No, the thinnest they do is 15+12.5mm. They are suggesting some insulation over the stud work to prevent "cold bridging". Wool type insulation is typically about half the U value of PIR.
I asked about vapor barriers, they said it is incorporated in the ins. plasterboard. House is mid terraces so not external wall. May insulate in between the rafters in the eaves section. Not much storage as would have to crawl in the space mainly going to be used as maintenance access.
That's correct, combination of the GA4000 & PL4000 + plaster top coat together provide the VCL - mainly in the PL4000 I would guess.
If its mid terrace, I wouldn't worry too much about massive amounts of insulation. Some is certainly better than nothing. Adding x amount of insulation will provide a benefit of Y Adding 2x amount of insulation will provide a benefit of 1.5Y I.e. double the insulation adds only half the benefit.
If you're set on building a stud wall before flooring you could set a trimmer joist into the gable wall central to to your room, chop out a pocket and slot a doubled up timber in that's the depth of your telebeams. Screw or bolt a joist hanger onto the telebeam to take the trimmer, then fit joist hangers on the trimmer to run a joist in from each side, end bearing on the wallplates. Build your stud without worry. 140mm is tight but I can see from your pic you own a compact Milwaukee, you should be fine. As opposed to building the stud wall, have you considered drilling and screwing 63x38mm cls on edge straight onto the wall with 120mm screws, insulating between with 60mm kingspan, cover with tri-iso multifoil (incredibly warm stuff), then counterbatten horizontally over the top, fixing to the cls. The void between battens is where you run your services then. Easier than building a full stud wall in an awkward location....
[QUOTE="Jord86, post: 1477102, As opposed to building the stud wall, have you considered drilling and screwing 63x38mm cls on edge straight onto the wall with 120mm screws, insulating between with 60mm kingspan, cover with tri-iso multifoil (incredibly warm stuff), then counterbatten horizontally over the top, fixing to the cls. The void between battens is where you run your services then. Easier than building a full stud wall in an awkward location....[/QUOTE] It certaininly is.
To get a 0.18 you need a total thickness of Kingspan PIR to be approx 110mm. 70mn between and 52.5mm over Check here for your own build up http://www.kingspaninsulation.co.uk/Services/U-Value-Calculator.aspx
This is the calculation I have done, it's not letting me change the U value or insulation thickness. I've went for 215m wall thickness. Not sure why celotex are saying I need a u value of 0.28? The wall isn't external as house is mid terrace so this why it may be different.
Are building control holding you to a certain value? If not I wouldn't worry too much about getting to 0.28u, think of it more as a target and see what combinations of insulation are possible in the situation/space you have, what u values they give then select the combo that best suits.
Not limited in room here so may as well try and get close to the U value a possible. I've set a laser line on the rafter and they are out with the floor beam so need to keep this in mind when setting out, think either the wall is out. Thinking it would be easier to dot and dab PIR onto wall then fix battens to the insulation before adding further ins. plasterboard, but don't see this method listed.
I'm not sure that would work too well, as well as dot n dabbing it, you'd need to mechanically fix it too. PIR has very little strength, so the battens would need to be secured through the PIR into the wall behind. If you did that it could work, but I guess the "recommended" method would be to first but up battens and put PIR between, then more PIR and plasterboard over the top of that. Much like koolpc did on his internal wall.
Think I have a plan. Going to cut up some blocks of wood from stud wall material to fix in between the rafter and wall then drill and screw this to provide a fixing for the wall plate for stud wall. Thinking of setting the stud upright about 10mm clear of the wall so I can squirt foam in between the gap to provide a fixing although stud would be fixed at top and bottom plates.
Ended up putting a stud wall in. Sole plate was made and fixed to wall using large angle brackets. Trenches were cut at 600c/c to accept uprights. Plate was made from two lengths of timber and half lapped at joint. Blocks of wood were fitted in between rafters and wall, tight fit and needed hammering in place. Once in correct position screwed in using large spax screw. All uprights were cut by hand with angle matching slop of roof. This was set using a sliding bevel and level set plumb. 2 screws secure it in to block. Going to put ends in after insulation in as will be easier. Thinking of putting in noggins at 12oomm high as insulated plasterboard will be fixed in horizontally. A bit tricky to do as mostly just cut square stuff. Having the laser made it easier as I could position it at notch ends on sole-plate and transfer a point. May run bead of foam behind stud wall using expanding foam.
Doubled up all rafters, left the middle one in between the windows for now, but once it has been framed will double them up.