How To Sister Attic Joists

Measure the old joists measure the length of the old joists and note how much they overhang any supporting walls or.

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. Hope this helps wg. However doing this does not fix the slant that the floor has taken since the old joists got damaged. Run the rows parallel and an inch.

In situations when sistering damaged floor joists with lumber of similar dimensions it can be easy to notch and slide the sister board into place. Then attach the sister joist using three 16d common nails driven every 16 in. Nail 10d or 16d common nails through the sister and into the existing joist. 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.

Driving 16d common nails in old hard wood is difficult. Lag screws if you re having trouble nailing. Take some extra time and jack the damaged area up so that the new lumber doesn t need to be. When the sagging joists are level apply a generous bead of construction adhesive to the existing joist.

Make two rows of nails spaced 16 inches or less apart along the length of the sister. A single rafter on each side is allowed per irc rules up to 48 between the two supporting rafters.