#Lvl beam span table how to#
#Lvl beam span table install#

I'd say that is more than 10PSF but online searches seem to treat person in attic as 10PSF?įor the first part of this, I am taking 20PSF x 14' (half the 28') to get my PLF of 280. 5PSF for attic dead load of insulation and 2圆 framing (stick framed with rafters, ridge board, etc and not webbed truss), 5PSF for two layers of drywall/mud, and 10PSF for what would be live load of someone crawling around in attic. I was going to use 20PSF for this rating. The ceiling joists have 5/8' drywall - let's say 2 layers - and then attic space above with blow in insulation. The ceiling joists are for two rooms, each room for this example has a length of 14' so the 'Span Carried' would be 28' but technically when I run the PSF I would halve this I assume? A LVL beam to be installed to support ceiling joists that are *not* continuous, as in they tie into the LVL beam. I believe this is the PLF rating? It seems a little too straightforward using the tech sheet so I want to make sure I am calculating correctly.

#Lvl beam span table how to#

I'm wanting to learn how to properly size an LVL beam when the specifics do not simply fall under the manufacture's generic span chart giving two options for premade spans. So again, if you just use 50% more members, you'll have 2/3 as much load per member, and 2/3 as much deflection, and the L/240 deflection criterion becomes an L/360 deflection criterion.Īnd the upside of the above reasoning is that it has a chance of convincing a plans examiner without having to hire an engineer.Hey all. Then an added wrinkle is that the 20 psf live, 10 psf dead table doesn't have the correct deflection criterion, it's L/240 instead of L/360 for floor joists. So instead of checking 40 psf live, 20 psf dead, 8' o.c., we check 20 psf live, 10 psf dead, 16' o.c. If we halve the load, and halve the number of members, the load per member is still the same, and the allowable span is the same. Since the table doesn't cover 8' o.c., we need to be a bit more resourceful.

#Lvl beam span table install#

The next simple multiple would be 8' o.c., which in practice you'd install as double members at 16' o.c. So you want to check whether a tighter spacing would work. On the table you referenced (the obvious first place to look), none of the 2圆 options work for a 12' span, even at the tightest spacing listed, 12' o.c. That is, sister each hacked 2x8 with (2) 2圆 DF #1.Ĭlick to expand.You've missed the point of my post. That means instead of 1 member per 24', you need 3 members per 24'.

So you'll need to double the member count for the loading, and add another 50% to reduce the deflection. Now you have twice the load (40 psf live, 20 psf dead) and need 2/3 of the deflection (L/360) compared to the table parameters. It tells us that (if douglas fir is your preferred species) DF #1 2圆 24'o.c. Start with 2018 IRC table R802.4.1(2), which is a span table (for rafters) for 20 psf live load, 10 psf dead load, and L/240 deflection. With a bit of reasonable extrapolation, you can do this via the span tables. So you should just consider your hacked up 2x8s to be oversized nailers and install new members that will be sufficient for the load and span on their own. In which case you no longer have that grade. For example, if you start with a particular grade which might allow knots of a certain large size as long as they are at least 2' from the edge of the member, and you remove 2' from the bottom of the member, now you may have a large knot right at the bottom edge of the member.

Hence I need a table.Īny advice on whether my plan to gain some height in the basement is a bad idea would be greatly appreciated!Ĭlick to expand.If you hack up your 2x8s, it's difficult to assign design values to them, as they will no longer be graded. Or rather than replace the existing joists, I will just sister each of the 2圆 joists to the existing 2x8 joists and trim off the bottom 2 inches of the 2x8's, thus getting at least as good as 2圆 joists at 12'Īccording to the IRC 2018, I can even use 2圆 Douglas fir-larch for this, but I was wondering if the LVL's will be even better (stronger and with less bounce). The reason I want to know thei is because I want to replace the basement ceiling (=kitchen floor) joists, which are 2x8 at 16', with 2圆 LVL joists at 12' so that my basement height will be 7' from finished floor to finished ceiling (after I finish it). SO I assume that Boise Cascade VERSA-LAM 2.0-3100 LVL can do better? Is it true? The IRC 2018 table R502.3.1(2) shows for Douglas fir-larch (the strongest lumber listed), a 2'圆' with 12' spacing can span 11' 4' (!) for dead load = 20psf and live load = 40psf.