Hello,
I will be getting a basic loft conversion done this summer & could do with some advice. It will only use 4x Velux windows as opposed to a dorma as i'm on a tight budget & need of space ASAP for bedroom. So it needs to be cool in the day & warm in the nights.
I inherited loft conversion plans for the house i recently bought & these have been already registered with the local council. I will get building & control involved before i actually begin.
I have a semi detached house with a high pitched roof . See diagram below.
I am trying to calculate the amount & cost of all the materials i will require & presently little stuck with insulation. I will supply all materials to builders.
I plan to use 25mm celotex between rafters (75mm air gap) & 50mm under rafters giving a combined U value of 3. Plans spec 25 & 40mm.
I am confused on how much of the roof i should be using the celotex on.
1. Against all of both roof walls - top to bottom.
2. Just on the roof walls beneath the new formed ceiling & above the side stud walls.
In both instances both sides of the roof will be fully covered with foiled 12.5mm plasterboards
+If 1 is correct will i still need to use 50+150 fibre glass in the new ceiling or will the celotex be enough ? Ventilation issues ?
-Will the side stud walls require additional insulation as the roofing behind them will already be insulated. If so how much ?
+If 2 is correct than i understand i will have to insulate above the ceiling 50+150mm fibreglass. Do i than just need to insulate the side stud walls ? If so with how much ? The area behind the sidewalls can than be left without further insulation ? I intend to make storage space in these with doors.
Another side issue is lighting. I intend to fit 9x 7w low energy spot lights into ceiling. How should the insulation in the ceiling be positioned so as not to cause the lighting to overheat ? I'm guessing this answer will possibly differ depending on if i go with celotex insulation using method 1 or 2.
Vent tiles will be placed in the roof above the ceiling height.
Please offer some advice/opinions.
Thanks
I will be getting a basic loft conversion done this summer & could do with some advice. It will only use 4x Velux windows as opposed to a dorma as i'm on a tight budget & need of space ASAP for bedroom. So it needs to be cool in the day & warm in the nights.
I inherited loft conversion plans for the house i recently bought & these have been already registered with the local council. I will get building & control involved before i actually begin.
I have a semi detached house with a high pitched roof . See diagram below.
I am trying to calculate the amount & cost of all the materials i will require & presently little stuck with insulation. I will supply all materials to builders.
I plan to use 25mm celotex between rafters (75mm air gap) & 50mm under rafters giving a combined U value of 3. Plans spec 25 & 40mm.
I am confused on how much of the roof i should be using the celotex on.
1. Against all of both roof walls - top to bottom.
2. Just on the roof walls beneath the new formed ceiling & above the side stud walls.
In both instances both sides of the roof will be fully covered with foiled 12.5mm plasterboards
+If 1 is correct will i still need to use 50+150 fibre glass in the new ceiling or will the celotex be enough ? Ventilation issues ?
-Will the side stud walls require additional insulation as the roofing behind them will already be insulated. If so how much ?
+If 2 is correct than i understand i will have to insulate above the ceiling 50+150mm fibreglass. Do i than just need to insulate the side stud walls ? If so with how much ? The area behind the sidewalls can than be left without further insulation ? I intend to make storage space in these with doors.
Another side issue is lighting. I intend to fit 9x 7w low energy spot lights into ceiling. How should the insulation in the ceiling be positioned so as not to cause the lighting to overheat ? I'm guessing this answer will possibly differ depending on if i go with celotex insulation using method 1 or 2.
Vent tiles will be placed in the roof above the ceiling height.
Please offer some advice/opinions.
Thanks
