Will a 95x95 beam warp?

[johan_p]

Hello,
I am planning to build a greenhouse with some old windows I have. I planned to have a beam 95x95 on posts, against which I would then mount the windows directly. I have managed to get hold of quite large old glass units with double glass at 1400x2000, so they are quite massive.

Is it fine to use a 95x95 beam, or is the risk of them warping and cracking the glass higher than if I use two 45x90 beams and tie them together? The posts are spaced just over 1.5m apart, so they should help prevent them from twisting too much, I think. What do you all think?

 

[Johan Gunverth]

Can't you use glulam instead?

 

[johan_p]

Can't you use laminated timber instead?

Unfortunately, my supplier doesn't have laminated timber in pressure-treated. What do you think is the best of the options I have?

 

[justusandersson]

Two screw-glued 45x95 on edge will be somewhat stiffer than a 95x95, but with the short span of 1.5 meters, both options work. Use strength-graded timber, preferably C 24.

 

[Johan Gunverth]

Most lumber dealers can order from Martinssons. They have 90x90 pressure-treated glulam, GL28-rated. I have personally made porch fence posts with their pressure-treated 115x115 and painted them.

https://www.martinsons.se/byggprodukter/limtrabalk-pelare/sortiment

 

[Villa1949]

Most lumber dealers can order from Martinssons. They have 90x90 pressure-treated laminated wood, GL28-rated. I myself made porch fence posts with their pressure-treated 115x115 and painted them.

[link]

Did you wait before painting the impregnated laminated posts, or did you paint immediately without letting them dry? How has it held up? What type of paint did you use?

 

[Johan Gunverth]

They were quite nice and dry when I bought them, so maybe 2-3 months later they were painted. Industrial primer/Bettgrund first and then Flügger Primolin oil-based naftalöst paint. At my dad's place, it has held up for over 20 years without any issues.

The mentioned glulam beams are available at Bauhaus by the way.