Window lintel

[Amrich]

Hello!

Problem Statement:

I need help calculating the dimension of the beam required above a door and a window for a new garage build with a loft. I am considering the beam as an inserted stud ("standing top plate"). According to online dimensioning programs, a glulam beam seems to be required. I am considering using two studs to manage with a smaller dimension of construction wood.

Conditions:

New garage build with a loft for residential load
Width 7.5m without partition walls
Roof slope of 38 degrees with tongue and groove and concrete tiles
Snow zone 3
Roof trusses at cc1200 plus a glulam beam between each truss
Wall frame (standing plus top plate) 145x45

I need to install a door and a window and need to remove a standing stud so the opening becomes cc1200. That is, either a roof truss or a floor joist is located directly above.

I would be very grateful if someone could help me calculate the dimension with either one or two beams/studs for this.

Thanks in advance!

 

[Amrich]

Assuming that I have used the sizing program on byggbeskrivningar.se correctly, then a 45x245 should be sufficient with a very small margin.

For example, can two pieces of 45x170 carry the same as a 45x245?

 

[justusandersson]

Can, for example, two pieces of 45x170 carry the same as a 45x245?

No, but two 45x195 if you can evenly distribute the load between them. I think it's better to lay glulam with the same dimension at c/c 600 mm, and equip every other beam with posts and collar tie. Then 115x315 would suffice for the glulam beams.

 

[Amrich]

I think it is better to place laminated wood with the same dimension at c/c 600 mm, and equip every other beam with rafters and collar ties. In that case, 115x315 would be enough for the laminated beams.

Are you talking about the trusses and the floor joists now, and not the header?

The trusses haven't been ordered, but the ones I've looked at are exactly the model you describe. Truss with laminated wood in the bottom chord at cc1200 and then a similar laminated beam between each truss.

Regarding the header then! How do I know if I get the same load on both 45x195 then?

Perhaps it's just as well to take a laminated beam above the door and window then. 42x270 or 56x225 seems to be a suitable dimension?

Does it need to rest on (notched in) more than one vertical wall stud on each side of the opening?

 

[justusandersson]

Good with glulam all the way. If the span is no longer than 1.2 meters, 45x245 is sufficient if you can get that size. It is not standard. Otherwise, use glulam. Better with a narrower one than two double if you need to recess into the studs.

Does it need to rest on (notched into) more than one vertical wall stud on each side of the opening?

Not if they have substantial dimensions and are braced laterally.