I have been in contact with a local building supplier who, through their contacts in the glulam industry, was going to calculate how much deflection a glulam beam would have when we would make an opening in the exterior wall. The supplier said that the company they traded with had sufficient expertise to calculate the job.
In the first response, the deflection of a 165x405x4000mm glulam beam would have a maximum deflection of 6mm. I mentioned that the beam was too tall and wondered how much deflection there would be if I went down to a 165x360x4000mm beam. After almost two weeks, and a couple of reminders, I got the answer that it would bend 14mm.
Is that reasonable, or did the supplier just get fed up with me and come up with something? It's been a few years since I calculated this in high school, so it's becoming a bit too vague for me to trust my own judgment...
Additionally, the supplier knew that the opening in the wall would only be 3400mm, but I received the dimensions above for the beams in the first response. It only struck me now that this should make a certain difference as well?
The house consists of 175mm lightweight concrete, 35mm air gap, and facade brick on the outside. It is a 1.5-story house with an extension on the upper floor that covers about half the length of the beam. The house is 8m wide and there is a load-bearing wall in the middle. The intermediate floor consists of 14cm reinforced concrete, cc 120mm on the rafters where there is no extension.
I also sent this drawing to the dealer.
I would like to go with glulam, but if what the dealer says is true, then it has to be steel. Just wanted to double-check if it's my only option.
If the only difference is the beam height, 360 mm instead of 405, then the 6 millimeters become 8.5 mm under the same load. Something else must have changed as well, if the deflection has increased to 14 mm.
Approximately, I think the loads on the beam seem quite exaggerated and thus its dimensions. A more reasonable dimension for a 3.4-meter-long glulam beam could be 165x270. With the same conditions, 215x225 would also work. It's not possible to zoom in on your drawing to see the measurements, so the answer becomes a bit vague.
I went over it again with the dealer and indeed they had calculated based on a 4m opening. I didn't have the energy to dig into why there was such a big difference now that the new calculation meets the requirements. The new deflection with 165x360 would be 8mm. Considering that there will be a sliding door below, I prefer to go a bit extra now that there is space.
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