Replacing a PT wood post in a P&P foundation

[BigMish]

I get the impression that post and pier foundations that are build with PT wood posts will need to have the posts replaced over the life of the building. Approximately how long will a post last before it needs be replaced? Are their any symptoms that will be exhibited which indicate it's time to replace a post? And (most importantly) how is this done, does any one have any books or articles they can point me towards on how to replace a post without moving the house?

Thanks, Mischa

[John_C]

If you use PT lumber treated for permanent wood foundation  .6 lbs. / cu.ft.    They will last a long time.   My porch is on 6x6 .60 treated posts.  Its 19 years and and shows no signs of deterioration.  The first signs will be the posts getting soft at or slightly below ground level.  If you can find PT lumber treated for immersion in salt water  2.5 lbs./ cu. ft.   you could just forget about them for a lifetime or two.

If you did have to replace a post you could build some blocking to spread the load over an adjacent area of the beam(s) and jack the house up enough to dig out and replace the post.  I replaced the sill plates and rim joists of a two story log home that way a few years ago.  Replacing posts one at a time would have been simpler, and that was an extremely heavy house.  

Concrete piers using sonotubes would also eliminate any worries about rot.

[glenn kangiser]

Symptoms would be uneven floor due to loss of support but as John C. says, you will likely not be the one worrying about it.

In the case of failure of one post you would usually be able to go  to either or both sides with a jack and new blocking and support it  on the surface.  It would not give you the lateral bracing but at that point you likely wouldn't be worried about it.  

In the case of settling of one post you could add shims at the top though if done per plan this should not be a problem.

A 20 ton jack - Harbor Freight $69 on sale should move any point on the house.

All of this is hypothetical at this point and in reality as PEG likes to say, Depends.

[John_C]

I was even lower tech when I jacked up the log house.  I already had a few small bottle jacks and bought a few more.  I think I had 4-8 ton and 4-4 ton jacks.   Of course when I started I thought I'd be replacing a 6 - 10  foot section of sill and rim joist. Before I was done I had replaced half the sun room and 1/3 of the main house, call it 75 feet.  Kinda typical for digging into rotted parts.

I think it was you, Glenn, who posted a jack that you attach to an air compressor.   If I ever have to lift something that heavy again, that's the way I'll go.

[glenn kangiser]

That is the jack I posted above - and it works manual also.  On air it is super.  I posted a picture of using it manually on the Underground house thread recently.

You were not real primitive as far as that goes.  My brother jacked up the outside foundation beam of our dads house on one side where there was no crawl space with a 25' telephone pole and leverage blocks.  

I think he was the the guy who said give me a lever long enough and a fulcrum to set it on and I'll move the world.

[John_C]

That would be your brother Archimedes?    I didn't know Kangiser was Greek.

[glenn kangiser]

Must have been a cousin.

Names German but we came over from Lithuania in 1889.  Apparently had been there for quite a while.

Archimedes eh?  Same guy that invented the screw water pumping method.