rowdy48

I have a 1200 sq foot ranch with a full basement built in 1957. The floor joist are 2 x 8 dimensional lumber and they span 12 ' 8". In the center of the house about six in a roll have had failures. One because the plumbers cut
a 4 inch square hole to run the tub drain. The joist beside this one was cut in half so the hvac guys could run the furnace vent to the roof thru the bath closet. The remaining four joist have failed due to large knots in the lumber that have cracked. Some time in the past someone added some angle iron to repair these joist but it was poorly fastened. Today I removed the angle iron and plan to saddle new 2x8's beside the damaged ones. Anyone have a suggestion as to the the type of fasteners (nails, screws or bolts) and how many to mate the old and new together ? Clearance is minimum in some areas. As luck would have it all these joist are over my electric panel and
water heater and I have had to pull the wiring and plumbing for access.
I'm considering 3 inch nails paired or tripled every 16 inches.

Stuart

nealtw

Three 3" nails every 16" is good. Wedge the old ones up a little with a couple 2x4s to the floor before nailing. You can drill a 2 1/2"
hole in the center for the plumbing without loosing strength, if you can't just lower it. The one cut out for vent pipe should be hangered from a piece that is hangered off the two full length joists. I would also use a couple tubes of flooring glue, glue between old and new and between new and floor boards.

rowdy48

The glue is a great idea. I plan on using a couple of jacks to ease the joists back level or as far as I can without additional damage. The plumbing will be dropped below the joist. I'm waiting on my hvac guy but since I'm replacing the furnace I'm thinking go with a high efficency and eliminate the vent to the roof. This will allow me to continue the cut joist to the center support beam. I have an issue with a vent run if I hang the cut joist off the ones beside it. I've had a support pole under it since I bought the house in 93. I'm adding a bath downstairs so I'm increasing the size of water heater and will use an electric to get rid of the vent. The payback for a tankless would take two long since I'm bugging out for a warmer climate soon.

Thanks for the response