How To Sister Attic Joists

How to reinforce an attic floor with sister joists clear the joist spaces pull out all insulation and any debris from all of the joist spaces so you can see the full.

How to sister attic joists.

If you want to play it safe not being required to double the joists you can just sister on the same size board getting as close to the end of the rafter as you can. Then attach the sister joist using three 16d common nails driven every 16 in. Predrill and drive 3 8 in. Lag screws if you re having trouble nailing.

Make two rows of nails spaced 16 inches or less apart along the length of the sister. However doing this does not fix the slant that the floor has taken since the old joists got damaged. Nail 10d or 16d common nails through the sister and into the existing joist. You will be exceeding the rule for minimum.

Hope this helps wg. Run the rows parallel and an inch. Take some extra time and jack the damaged area up so that the new lumber doesn t need to be. A single rafter on each side is allowed per irc rules up to 48 between the two supporting rafters.

Driving 16d common nails in old hard wood is difficult. Insulate basement rim joists.