Here’s a sketch of the shop I hope to start soon. I’m pretty good with framing and have used post and beam for sheds and stick framing in the house. I am at a sticking point in design over something I’ve not used before, LVL (aka microlam). The sketch shows the front of my proposed shop as 22 ft across and shows a simple shed roof at a 2/12 pitch. I’m in SE Louisiana and have short duration snow loads, though rarely even that. Halfway across the 22 ft and at rafter level you see an X marking the spot for a beam that runs the length of the shop, 30 ft. You are looking at the end of the beam. I plan to put a post, built up from dimension lumber at the halfway point, or 15 ft. I’ve been searching the tables and having a tough time with them for sizing the beam. The requirements as I see them: I want a beam that can span 15 ft and another beam end to end that can span the next 15 ft to cover the distance front to rear of the shop. I know there will be some days when I’ll wish the was no post in the middle of the shop, but I also see it as a way to have a drop point for dust collection and electricity, avoiding cords and hoses running to walls. I can live with it. I’ve called a couple of local lumber yards and they (liability) want me to spec the size. Seems most advice says go to a “real” lumber yard and they will call the manufacturer who will help you size it. Let’s say response has been slow so far, but I still have some diminishing hope. – What’s on top? I want the beam to support the rafters directly; I will not use ceiling joists. The rafters will be 2X8s 12 ft long, 24” oc, overlapped by a foot each and nailed together atop the beam. I want to sheath the roof with plywood, probably 5/8” sheathing grade. I will use tar paper and then a bubble foil, strip every three ft with 2×4s and fasten a 26 ga. metal roof – not a really light or really heavy roof load unless…. – A few years ago we had an eight inch snowfall here, extremely rare, and my home made house and sheds came through that just fine. I need to be able to “weather” that event should it occur again. I’m 62 and it was the greatest snowfall I’ve seen. WE have had sustained winds in excess of 100 mph (Katrina) and The 2×6 walls will be completely sheathed with plywood for shear strength. – So – in my amateurish estimation, there’s a deadload of 15 psf and a live load of short duration, possible of 20 psf? That would be the rare snowfall. If I correctly appreciate the physics involved, the roof loads are supported on one end by the the 2×6 walls with double top plates and shared on the other end by the beam they rest upon. – Thanks to the curious who have hung in with me thus far. The “Calling all LJs” part of this is has anyone built such a beam to span 15 ft using (3) 2×12s? My case would involve (6) 2×12 as I place a second beam end to end and I’ve considered a slight stagger of the middle 2×12 by about 1.5 inches to created a tongue and groove effect for the end to end joint where the beams meet. I would join the beams additionally with scabs or metal plates. – I know LVL is in style these days, but I’d like to know my options. Getting some SYP 2×12 is easy work, but ordering the LVL is getting to be a pain. I’ve seen the rules of thumb for LVLs such as 1” of depth for each foot of span. My unsupported spans end up being close to 14 ft with the required bearing surface on each end, so I’m thinking two 1-3/4” X 14” AND 15 FT LONG lvls nailed together would make one beam, then do it again and place it end to end. My goal here is no sagging no regrets! – Thanks so much for sharing your experience with 3 2×12s and or lvl doubled up.
-- Like Guy Clark sez - "Sometimes I use my head, Sometimes I get a bigger hammer"