Choice of beam

[Derbyboy]

I live with it! Thank you Justus.

 

[Derbyboy]

I've looked at some prices and unfortunately, it's only high-income earners who can afford steel nowadays.

A VKR 120x120x8 at 12 m costs 15,000 kr.

 

[justusandersson]

If you use glued laminated timber, you can recess the secondary beams to save height. What is the maximum height?

 

[Derbyboy]

I will measure exactly as soon as possible.

The max height is 430 mm I believe.

The profile for kanalplast is 45 mm thick.

 

[Derbyboy]

Could it look nice to use glulam for the main beam and pillars and then use VKR for the secondary beams?

It will be like a metal roof resting on a glulam frame.

 

[justusandersson]

I would stick to glulam, then it's easier to insert the secondary beams. Additionally, it's difficult to lay glass on metal due to greater movements.

 

[Derbyboy]

I have started looking into glulam again. I found a secondary beam that I think suits me, it is 56x180 but unfortunately, it's not a standard size so it is not included in the calculation program at Swedish Wood.

How long can it be at most between the load-bearing beams?

Max deflection 8 mm
Cc 1015 between secondary beams.
Roof slope 5 degrees
Snow zone 2
Roof weight 0.27 kN

If I enter the dimensions into the calculation program, the maximum span for 42x180 is approximately 2850mm at 8mm deflection (L/344)

 

[scorp1on]

I've started looking into glulam again. I found a secondary beam that I think suits me, it is 56x180, but unfortunately, it is not a standard dimension, so it is not included in the calculation program on Svenskt Trä.

How long can it be at most between the load-bearing beams?

Max deflection 8 mm
Cc 1015 between the secondary beams.
Roof slope 5 degrees
Snow zone 2
Weight roof 0.27 kN

If I enter the dimensions into the calculation program, the max span for 42x180 is approximately 2850mm at 8mm deflection (L/344)

Depends on what strength and stiffness properties you have. For GL28cs, you get a final deflection of 8 mm with 56x180, L = 3m, and your other mentioned parameters.

 

[Derbyboy]

The one I looked at had GL28. Feels stingy to go from 42 to 56 and only get 150 mm more.

What could I get with 2 pieces of screw-laminated finger-jointed C24 45x145?

Träguiden says that 240 cm is ok (8mm) with 1 piece of C24 45x145.

 

[scorp1on]

It is not entirely straightforward to calculate such a connection as you have contributing strength from both the glue and the screw. A detailed calculation of that specific connection is required (which I currently do not feel like doing). You will get less than 8 mm in any case.

 

[Derbyboy]

That's good enough, thanks!

Another option is to use 45x145mm in the highest possible class, maybe get a hold of C30 or C35. Then I can reinforce with flat iron 6x140mm on one side of the beam.

 

[scorp1on]

Yes, if you can get hold of c30, it's a better option with less work.

 

[Derbyboy]

I have thought about it and decided to construct the entire structure with glulam beam 90x180. It's going to be a big build. It would be really nice if someone could take a wise look at the drawing and provide feedback.

I entered the data into svenkt trä and got the following:

 

[Derbyboy]

The height I have to work with is 430 mm and then it becomes:

180 primary beam
180 secondary beam
26 profile

Then the secondary beams are at an angle, so they rise a few cm behind the primary beam. Additionally, I need a few cm to attach the sheet to the existing eaves.