Hi,
What would be the opinions of the masses when insulating an attic conversion - what type/thickness is best.
I have been doing some research and a neighbour of ours had a conversion done with the following:
200mm fibreglass to be fitted behind the walls of the new attic room
kingspan thermopitch 65mm rigid boards to be fitted between rafters on roof
internal ceiling will have gyproc foilback boards
In terms of average, good, very good - what rating would the above get - how could it be improved?
I am assuming it is in compliance with the building regulations as she obtained a cert of compliance after the conversion.
Thanks,
pbyrne
do you mean in the 1.2 high stud walls?? If so then squashing 200mm into a 100mm space only equates to 100mm of insulation. generally the best solution here is 100mm PU board (xtratherm rafterlock) bewteen the rafters all the way from the eaves to the ceiling height, and across the ceiling in 150mm. then slab out with 47.5 insulation backed platerboard... 35mm insulation and 12.5 plasterboard. I wouldnt insulate in the small stud walls... because people use the air cavity as storage space and incorporate doors into these walls.200mm fibreglass to be fitted behind the walls of the new attic room
what do you mean do you mean in the 1.2 high stud walls?? If so then squashing 200mm into a 100mm space only equates to 100mm of insulation. generally the best solution here is 100mm PU board (xtratherm rafterlock) bewteen the rafters all the way from the eaves to the ceiling height, and across the ceiling in 150mm. then slab out with 47.5 insulation backed platerboard... 35mm insulation and 12.5 plasterboard. I wouldnt insulate in the small stud walls... because people use the air cavity as storage space and incorporate doors into these walls.
what do you mean do you mean in the 1.2 high stud walls??
I wouldnt insulate in the small stud walls... because people use the air cavity as storage space and incorporate doors into these walls.
If you check the next page (page 8.) see the top pic showing the pitched roof with attic space, this is what i mean. I would recommend it even more if you plan on using the cavity as storage space. It may be slightly more awkward work, but it is definitely with it compared with the alternative.Yes - that is the case here also - it is used as storage space with doors. Would you say then that insulating the stud walls is redundant if the rafters are insulated all the way down to the eves (unlike the SEI diagram above?)
If you check the next page (page 8.) see the top pic showing the pitched roof with attic space, this is what i mean. I would recommend it even more if you plan on using the cavity as storage space. It may be slightly more awkward work, but it is definitely with it compared with the alternative.
For my conversation with the attic conversion people - what would be the advantage of "xtratherm rafterlock" over the "kingspan thermopitch 65mm rigid boards" they are recommending?
65mm of thermapitch is not really up to the job although it probably does meet the building regulations for refurbishment. See here [broken link removed] for tables. Be carefuly when reading the tables and note at the bottom of each one that the underside of your rafter must be lined with 25 mm insulation backed plasterboard to meet the stated u value.
Rafterloc comes in at minimum size of 100mm.
Thanks for those replies - in terms of cost is there a massive difference between the two products?
I have no idea how much I would require but say it was 100sq. meters - what would be the price approximately for each one.
Thanks again.
Looks like 65mm is the max to allow enough breathing space for air to circulate. Is that correct or could we go up to 75mm - they were not exactly sure if that was ok.
(6) I will also be insulating the floor of the storage area - undecided on that though - anybody have a comment on that - I think it is required. If insulating it some of the 65mm kingspan thermopitch would do fine (but might be an expensive way of doing it when compared to just putting 200mm of fibreglass down - comments?)[/quote
I don't think it's a good idea to put down thermopitch between your downstairs and insulated storage space - it defeats the purpose of insulating from eves plus it will cause a build up of moisture under the boards as you very likely don't have a vapour membrane on your ceiling or a minimum of foil backed plasterboard.
Premium Insulation Roll 400mm(W)x100mm(T)x4m(L) - 3 Roll Pack
uvalue = <need to find>
thermal resistance = looks to be specified in a different form:
[broken link removed] - how can I compare?
cost = roughly 15euro per sq. meter (or 10.5 per sq. meter for comfort range)
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