Hello!
My constructor has indicated on the construction drawing that I should nail a 22x195 plank onto the kertobeams, which are trusses measuring 56x450. These planks should be positioned with a five-centimeter upward offset from the kertobeams to create a natural air gap for the roof. Then, I should nail the roof decking onto the 22x195 planks.
To me, it sounds strange not to use the kertobeams as a base for the roof decking.
The 22x195 planks are supposed to form the eaves themselves, and the kertobeams are inside the wall and not visible from the outside.
The only things I can understand with this are:
1) I can get 45 cm of insulation in the roof. (But 40 should be enough, right)
2) If the roof fails at the outer and underlay felt, the moisture will initially go to the roof decking and the 22x195 planks, and not the load-bearing structure = kerto.
Tomorrow, I will build the roof and am hesitating until the last minute about this unusual method.
Best regards,
Marcus
My constructor has indicated on the construction drawing that I should nail a 22x195 plank onto the kertobeams, which are trusses measuring 56x450. These planks should be positioned with a five-centimeter upward offset from the kertobeams to create a natural air gap for the roof. Then, I should nail the roof decking onto the 22x195 planks.
To me, it sounds strange not to use the kertobeams as a base for the roof decking.
The 22x195 planks are supposed to form the eaves themselves, and the kertobeams are inside the wall and not visible from the outside.
The only things I can understand with this are:
1) I can get 45 cm of insulation in the roof. (But 40 should be enough, right)
2) If the roof fails at the outer and underlay felt, the moisture will initially go to the roof decking and the 22x195 planks, and not the load-bearing structure = kerto.
Tomorrow, I will build the roof and am hesitating until the last minute about this unusual method.
Best regards,
Marcus
One reason might be that this way you can fit more insulation without resorting to Kerto beams that cost a fortune. This is how my engineer has reasoned and complemented 45 mm wide kerto with 45 x 145 regular timber nailed at the outer edge.