How to splice roof trusses?

[BigGitt]

Thinking about how to extend rafters that are 45x145? The idea is to insulate the sloped roof with about 285mm. The simplest is a 45mm air gap and then 2 times 45x95 plus battens. I'm thinking about thermal bridges and wonder if it's okay to do as follows: 45mm air gap, 45x95 horizontal, 45x95 vertical between the rafters, and battens. Is this feasible in terms of load-bearing? Regarding plastic, I won't write anything. It is necessary to have it.

 

[prototypen]

If you make a sketch it's easier but it sounded like a lot of wood for that påsaling.

Protte

 

[BigGitt]

A quick sketch. Masonite should be used for the air gap.
What do you think?

 

[prototypen]

Unnecessarily much timber for the air gap, rip a 22x95 board to 22x45.
The horizontal 45x95 feels unnecessary, but it's a lot of work to cut board pieces, attach to the truss, and place the vertical 45x95 centered on the truss. If you have the timber, maybe your solution works.

28x70 (sparse panel) I would replace with construction plywood without hesitation.

Protte

 

[BigGitt]

Unnecessarily much timber for the air gap, split a board 22x95 to 22x45. The horizontal 45x95 feels unnecessary but it's a lot of work to cut board pieces, attach them to the rafter, and attach the vertical 45x95 opposite the rafter. If you have the timber, then maybe your solution works.

28x70 (sparse panel) I would replace without blinking with construction plywood.

Protte

Why construction plywood in a sloping roof?

22x95 split in two is ok. Or 45x45 split in 2. / have saw.

How should one prevent thermal bridges?

 

[BigGitt]

I don't dare to copy other people's images. What do you think about the salning according to the 3rd photograph from the top?

http://alvsbyhus.forum24.se/alvsbyhus-about1408-0-asc-210.html

 

[prototypen]

Plywood, anything can be placed anywhere.



Protte

 

[prototypen]

A completely obvious solution, similar to my solution but simpler since my "boards" are already there, do like Älvsbyhuset. And plywood.

Protte

 

[BigGitt]

I would have preferred to skip your "bräda" and use the column to lay the insulation horizontally. Protte, do you think the rafters will handle Skåne's load?
I'm thinking about it with snow. On the other hand, people on the Ähus forum did it...

What do you think?

 

[prototypen]

If the trusses are calculated for the snow load that you have, they will hold. If you're worried about the strength, none of the suggestions for sistering will provide any increase in strength.

Do like Älvsbyhus, simple and good. My whatever board is replaced with the collar beam and the post down by the floor.

Protte

 

[BigGitt]

Ok. Thank you.

 

[PCLarsson]

Personally, I plan to eat outside, don't want to eat in the existing space...

Regards,

PC

 

[prototypen]

But then you'll get a "new outer roof".

Protte

 

[BigGitt]

Or he has plenty of time and money

 

[PCLarsson]

But then you end up with a "new outer roof".

Protte

That's correct, I want to replace my outer roof which is currently made up of eternit panels and an underroof of internit. And in connection with replacing these, I plan to also add external insulation.

Regards

/PC