Hello all,

I have a section, of about 6 feet, or rotten sill plate. I've solved my moisture problem but have to replace the plate.(the header is near to sitting on the foundation blocks).

I was wondering if anyone could offer any advice on how to raise the house up--just a small section of it--or if anyone to direct to any web or book resources.

Any advice would be appreciated.

I don't think you have to raise the house. You can temporarily support the structure and just cut out the rotted part and replace it. Use a heavy hammer.

...but the sill has disintegrated underneath the joist, and the joist has thus sunk down an inch and a half.

If the joist has dropped you will see damage on the wall area above.
You have a few choices.
If the damage is not effecting the operation of doors or windows above and is simply cosmetic you can simply cut the joist off to shorten it so the new treated lumber sill can be hammered back in.
If the josit is effecting a door or window you will need to open up the wall above and correct this settlemt by placing small jacks in the proper areas and gently lift the suspect area back up. this can be a tricky job and best done by someone who is familure with this type of work.
Be sure to support the floor joists where needed with temporary supports to prevent additional settlement if removing the entire six feet at once.
Also be aware that the exterior rim joist most likely has been damaged as well and should be repaired if at all possible. If the area is behind a porch and you cannot gain access to this joist be sure to nail blocking between each floor joist to prevent twisting. This should be done once the sill is replaced.

Take Pictures! Quite often when a home is sold any repairs like this need answers. When doing it yourself your future buyers will need some assurance that what you did was proper and you did not simply re-face the sill so it looks repaired. As an independent inspector we see this a lot.

Thanks much. That's very helpful. The area has to be raised about an inch, so I will have to use the jacks.

May I follow that with a couple more questions?

The rotted sill follows parallel to the floor joists. When I jack up that section how many joists should I jack up? I don't imagine that simply jacking up the single joist that runs parallel would be all that smart.

What manner of jack(s) would I use?

No need to support the joist as the wall effected is not a real weight bearing wall as compared to the ones where the joist rest.

If at all possible try to remove the siding on the outside of the house and work from that side. As the joist that runs nearast the sill will make it difficult for you to gain the necessary access to do the job properly.
There is nothing needed to jack, but if you want to lift the wall we use bottle jacks that can be bought or rented.

The method of doing this job is going to depend largely on how affected the parallel joists are. You are going to need to do a lot of measuring. Start with the joist closest to (and parallel to) the sill and run a string along the bottom of the joist from end to end and see how much sag is present in the joist. Do this with each joist until you get to the joist with no sag. This is going to tell you where to place the jack, if needed, but because these joist are parellel to, not perpendicular to, the affected sill, then there may not be much sag in the rest of the joists.

If not, then you may be able to fix this by simply wedging the joist that is above the affected sill and then placing the new sill in two pieces, instead of one 6 ft piece (this is fine as long as you caulk the joint, especially from the outside).

Either way you do it, having outside access is going to be key. If you don't, interior access may be tricky, depending how close your next joist is to the foundation wall.

I used 4 of the cheapest bottle jacks at GI Joes ($20 ea) to support entire 8 x 13' kitchen.
Then i built foundation rite around it, slid new TJI's in between the old joists & used car jack to shoulve it over 18" to it's new location. Drag & Drop Kitchen Pod.

Main problem was getting enough stuff under jacks to keep them from just sinking into dirt.Double Pcs. of 2x8 works well. DO NOT work under hydraulic jacks. Use them to lift ONLY and then get solid wood or concrete blocks next to them and set the load down.

You could probably use just 2 for what you need and one 4x12 or 6x8 perpendicular to floor joists. Lift just enough to be able to smash old goo out and install new treated sill. Buy a 3" Square Simpson "washer" to put on top of each jack post. That keeps it from just smashing into wood beam because the jack posts are too narrow otherwise.

AGAIN - lift only with your body well outside "the zone". Set it down on solid blocking B4 you go under it!

I thank you all very much. What a wonderful resource you are. Again, thank you for sharing your knowledge and experience. It's greatly appreciated.