Queston from non-Engineer--Sister Floor Joists with lumber or angle iron?
I hope it is kocher for a non-engineer to seek DIY advice on this forum, as that is what I am doing.
I am sistering floor joists in my 1929 home. The joists are 16 O.C. and are either 2x8x16, 2x8x14, or 2x8x12'. Ive already done the sistering on one side of the house. I jacked the joists to make the floors approximately level, wedged sisters next to the full length of the existing joist, glued, and bolted with 3/8 bolts spaced at 1 intervals in a W pattern. When I removed the shoring, I lost half of my leveling in one part of the house where the joists are 16 long and there is a wall directly above. (I jacked up Ύ, but lost half of that.)
My question concerns the best way to remedy this. Im thinking of either adding a second sister to the sagging joists, or adding angle iron to the bottom of the sagging joists. Id like advice on which strategy is best and, if I do the angle iron, what size would be best.
If I do angle iron, I dont want to drill any more holes in the joists, so I would utilize the bottom holes Ive already drilled (1-1/2 from the bottom of the joist, at 2 intervals). So the bolts would be in a straight line 1-1/2 from the joist bottom at 2 intervals. Because angle iron comes in 20 lengths, Im thinking of using 10 lengths of angle iron centered on the midpoint of the joists. Regarding angle iron size, it seems to me that what matters is the size of the vertical part that is bolted to the joist and not the horizontal (bottom part). Im considering 3 x 2 x 3/8 or 4 x 3 x 3/8 or 5 x 3 x 3/8.
I note that the weight of a 10 length of 3/8 angle iron is 60# (3x2), or 90# (4 x 3), or 100# (5x3), which compares with 26# for 10 of 2x8 lumber. Im concerned about adding too much weight.
Any advice would be much appreciated.
Thanks,
Randy