Help with sizing roof beams

[SSlangen]

Hello,

I need help sizing the roof beams (glulam) for an attached garage. Shed roof with a 3-degree roof pitch and with a roof terrace. Snow zone 2.

Grateful for any help.

 

[Tompafix]

Hello,

I need help sizing roof beams (glulam) for an attached garage. Single-pitch roof with a 3-degree roof angle and with a rooftop terrace. Snow load zone 2.

Grateful for any help.

Try entering your values here
https://www.byggbeskrivningar.se/dimensionering/med-meny/?cid=931

 

[justusandersson]

I don't think construction plans work when you're going to have a rooftop terrace. Laminated wood beams with about a 10 m length at c/c 600 mm need to have substantial dimensions, preferably 140x405. If you splice the beams over the partition wall, you can manage with 140x315 and even smaller over the narrow part.

 

[SSlangen]

The idea is to share the beams between the wall, so the beam length will be 6.5-7m.
What loads come from a rooftop terrace?
Can I assume that snow load and "max" load do not occur simultaneously? I mean, no one will be on the terrace when there's a lot of snow...

 

[justusandersson]

The so-called useful load (people and furniture, etc.) for a terrace is 3.5 kN/sqm. Snow does not need to be considered at the same time.

 

[SSlangen]

Thank you for the good answer!
Which deflection is acceptable?
Is it "correct" to use the dimensioning aid on building descriptions and set snow zone 3.5?

 

[justusandersson]

No. Snow zone 3.5 means that the basic value of snow load on the ground (in a 50-year perspective) is 3.5 kN/sqm. The actual value then depends on form factors such as roof type, roof pitch, risk of snow pockets, and additional conditions. The actual value can be both lower and higher. The maximum deflection for a roof is 1/300 of the span. Additionally, one should check the flex when it is to be used as a terrace.

 

[SSlangen]

Hi, I have been playing a bit with the sizing help on building descriptions...
If I assume a custom load of 3.5 kN/m2 and snow zone 1, could it be close to reality?

 

[justusandersson]

Snow zone 2 should be in Norrtälje. If you can insert 3.5 kN/sqm then it must be correct.

 

[SSlangen]

Ok, but then the calculator computes the loads simultaneously, right?
3.5 kN/m2 becomes the design load...
Or am I thinking wrong?

 

[justusandersson]

Tell me your conclusion, and I can say if it is correct.

 

[Daniel Barnaniel]

Off topic as it may be, it must be said, Justus - goodness, you are so kind and helpful!

 

[justusandersson]

There are surely some who think I'm stealing their jobs... I have very good tools, so it's not a huge effort.

 

[Daniel Barnaniel]

There are probably a few who think I'm stealing their jobs... I have very good tools, so it's not a huge effort.

You are, literally! Do you charge sometimes too?

 

[justusandersson]

No. I cannot deliver any documents.