Hi,
I have started to create a stud wall 50mm from the interior single brick wall and filled it with 50mm Kingspan PIR board.
I only went up as high as the roof beams, and originally I was going to cold roof insulate the roof.
Now I intend on creating a warm roof come summer time, does this mean what I have done so far needs to come out? I have only taking the stud wall and PIR board up to the beams currently, not all the way to the flat of the roof.
I guess my questions are..
1) Is it best practice to have a gap between the single brick wall and the stud wall?
2) If it is, does it not matter that some cool air from the cavity, can make it on to small areas of the interior roof? As in the cavity surely goes floor to ceiling?
Thanks
Are you a tradesperson and able to answer this question?
Cavity walls insulation is minimum 150mm now but can use 100mm pir board in studded external walls against external brick skin
Warmer roof you need to put 100mm pir board on roof and reboard it before you put your flat roof surface on
Cold roof only has the pir board in between rafters also 100mm insulation pir boards
Answered5 November 2023
2
Anonymous user
Hello,
Creating a gap between the single brick wall and the stud wall is indeed a common practice for insulation purposes. However, the specifics of your situation may require a more detailed analysis. It's advisable to consult a professional to ensure the best approach for your project. Concerning the cool air from the cavity, its impact might depend on various factors, including the overall insulation design. To gain more clarity, discussing this with a construction expert could provide better insight into your specific case.
Best regards,
Surrey Constructions
When a ‘Warm Roof’ construction is used, The void below the insulation should be roughly the same ambient temperature
As the room Below. A single brick wall shouldn’t have any holes in it to allow air in unless this was built as a timber frame
Detail. Then you would have cavity trays and weep holes.
Full fill insulation should be taken up to the underside of the warm roof insulation.
Full filling the cavity will prevent any air going up through the cavity.
If the ceiling joists are preventing the cavity insulation meeting the warm roof insulation. Then insulate from above the stud
Wall header where the cavity wall insulation had to stop and the underside of the warm roof insulation or structural ply
Supporting the insulation. This will prevent any leakage of air into the warm void of roof.
Cavity wall is 150 mm under new regs . Warm roof insulation is 150 mm /160mm not 100 mm . You don’t need to vent a warm roof only a cold roof where insulation is in between joists and under . You should call bco before you do anymore to make sure you aren’t wasting your time and money. Cavity wall needs correct u values dritherm or rigid Kingspan/celotex are your best options .
