Due to an out of control moisture problem (now being solved with ventilation and dehumidification) there are 1 wooden and 6 steel posts in my basement that are seriously rotted. The wooden one is really old and I know that those rot from the bottom and slowly sink. The steel ones are filled with cement but there is so much rust that I’ve been told they should be replaced.
The contractor I hired wants to replace them all with pressure treated 4×4 posts. He says they’re easy to install, work just as well and last just as long as steel filled with cement.
Is that a good idea? Are the cement filled steel posts better?
Replies
Hello? Anybody out there? I was hoping someone would help me out by offering some advice or an opinion.
I wouldn't replace steel lallies for wood without an engineers review and approval. In fact, he would be the first guy I consulted on this, just before I made a call to the local building inspector. The BI in your jurisdiction would have the final say, but would most likely defer to the engineer.
As it is structural, a permit is required, at least in these parts.
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depends on the load on each lally..... maybe the 4x4 is sufficient ... maybe not
i'd make sure they were .60 instead of .4 or .25 and if there is any point load you may need the lally
lally's are all rated for their loads... check the mfr.
I don't know what a 4x4 is rated at
I have used both as well as 6x6 pt. The controlling factor is the weight that is carried by the girder that the posts are supporting. Unless this is an exceptional amount, the wood will do fine. If the girder is wood, it will compress before the end of a wood post. Since the metal plate at the top of a typical lally column is about the same size as a 4x4, if the load is too great it will compress the bearing surface of a wood girder. Buckling of a wood post will not happen unless there is a very tall basement or an exceptionally high load.
I like wood because you can use it easily for other things. But most of the buildings we have been doing recently have steel 4x4 tubes that have 1/4" walls. The architects do not like lally columns for the very reason the yours need to be replaced. The thin metal rusts out too easily.
Unless you have an unusual house, I would trust your contractor to make the right choice based on his experience.
Steel tube carries a heck of a lot greater load than wood, particularly if it is filled so it cannot crimp and fold. If you are changing your load bearing capacity you had better be sure the steel was over kill. To get a tight fit with wood you need to jack the beam and then let it settle on the wood. The only other option with wood is to place and shim tight. Shims tend to compress. Will the beam jack up without cracking plaster above? The screw jacks allow you to place and create pressure more easily. For my money buy a high quality thick wall post and paint it.
Six of one and half a dozen of the other, IMO
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Sounds like the wood is not a bad idea. These are posts under a wooden beam that crosses under floor joists about mid-way across a 12 ft span. We're not changing anything above and the layout of the rooms looks like it hasn't ever been changed. The joists are pretty large. Not sure exactly how large - most of them look like small, peeled trees. (200 year old house.) They're chestnut and a few have rot and have been sistered with 2x8s. My contractor thinks the posts are there just to take some bounce out of the floor.
Thank you all for the help and advice. Now I know enough to keep my trap shut and let the contractor do what he thinks is best.