Floor Joist Treated Or Not

Photos 1 and 2 show galvanized steel joist hangers supporting nontreated.

Floor joist treated or not.

If there is a doubt then use pressure. The joists were pressure treated lumber so i was surprised at how badly decayed they were. Yes pt lumber can be used for framing including floors. Had started to rot on top of the joists due to the trapped moisture under the decking.

Drop girders or beams that set in a cut out of a foundation wall should not have to be treated as long as they have a barrier between them and the concrete. Because of this the tail end of the new lumber is not supported. Deck joists rotting from the top edge down because the deck boards and debris keep them damp for weeks after rain. The allowable stresses of pt lumber are lower than non treated lumber which means it can not span as far.

I finished a free standing deck a few weeks back and used ss deck screws ss hangers even ss hanger nails. And you thought this was going to be easy. The joist hangers used in construction with both sawn lumber and manufactured joists are usually galvanized zinc coated. Also pt lumber is corrosive so connections need to be such that they resist corr.

Floor joists in crawl spaces are closer than 18 to the ground. Not all floor joist lumber has the same strength and even wood of the same species but of a different grade will have different strength characteristics. Usually when a joist gets sistered the new lumber does not span the entire length of the old joist. It is important to jack this end level to keep the floor from sagging any more and to keep the joists from splintering later.

On a related note i had to replace some deck joists a while back on a 8 year old deck in ct along the shore. Remember that treated pine is only slightly more expensive than regular pine. So he has two rot fighting tips for deck owners and builders. This treated lumber is bolted to the foundation and the floor joists typically rest on it.