Need to jack up my home from the basement and replace a section of an insect damaged sill & replace or sister up 1 or 2 joist. I have a 90 year old ballon framed 3 floor colonial. What size or type of jacks per foot ? Is there some instructional step by step help available some where?

Which way does the basement floor joist go in relation to the sill plate you need to replace? I've jacked up many houses and can give you the setup here.

How long of a section needs jacked up?

Floor joist pattern?

What's the basement floor concrete?

About how thick is the basement floor?

Need a lot of details here so I can get clear picture in my mind.


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90 degree, not parallel. Joist are 12' long and 18" center, they span from the sill to the center of the home and are nailed to a center 8 x 6 beam that has several colums supporting it. One can visually see how many off them have started to separate from the center beam so I will have to also use some Teco plates to better secure them when the floor gets jacked back up a little. We have a concrete floor that I will assume is 3 - 4 " thick. The floor above this area has sagged, I would guess over an inch and a half. A 4 foot section of the sill and some joist have been seriously undermined from carenter ant damage.

Thanks for the good info. 90 degree is great parallel is a pain.

The first attack is to get those joist to the center beam secured better. I know it will be a pain. Those joist need support the before we jack up outside plate.

This needs done first because you need the other end of the joist to jack under and those joist need to be Locked onto the center beam.

How long of old outside plate needs replaced so I can get right back with the big list?

I just saw you are online and want to get this done for you



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Once the joist are properly supported on middle house beam then we can address the outside plate.
Take a 2x10x? And lay it on the floor. On top of that lay a 6x6x? And toe screw that to the 2x10 and center the 6x6 on the 2x10. Now that can be lifted under the house joist and there is room beside the 6x6 to screw through the 2x10 to hang the new 6x6 beam.
Now add a 2x6x? Flat to the bottom of the 6x6 to make it a 6x8 in height. Beside that now 6x8 in height add a 2x8x? You now have a 8x8 beam for the post.

Before you raise the new beam cut some 2x6x15"+ spacers to go between the joist bays and flush to bottom of joist. This will stop any folding or twisting on the joist when you jack the 6X6 which will be under the scabbed braces.

Get 2 round house post (big box stores has them they have a plate and fat 1+ screw and round plate it screws through that fits in the post and the post is in two pieces and can be adjusted.) Set the finished beam about 8 inches form the foundation wall Check the rating on the big box stores I believe they are 10,000 lbs support a piece.

For the bottom of these house jacks post lay a minuim of 2pcs of 2x10 flat on the concrete floor to spread out the load. To do a long run make more beams and split the beam between the joist bays.

General spacing of post for keeping joist set and not raised is 6' between post. To actually jack it up and another post and 3 foot OC on post.

My beam may seem big or over kill but the actual house needs supported and for temp support it basically matches the house beam. When you set the temp house post use a scab under the already bolt beam to catch the 6x6 and the 2x8s all together.

You don't necessarily have to lift the actual house to replace the house plate just lock it in with full tension on the new post and beam. You can shave off the new treated foundation plate. Don't forget the 1/2 anchor bolts for the new plate. The first should be no more that 1 foot off the corner of the house and no more than 6 foot center by code here.



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The center 8 X 6 that the joist are nailed to also has a 2 X 12 under it that the joist rest on for support. They pulled away at the top because the outside sill has sagged. Once the outside has been lifted they should come back to true for attachment with Teco plates, I HOPE. I will remove all the plumbing that's in my way (heat headers, Gas & water lines) and start to prepare my temp. beam. Then I will remove the outside clapboard and expose the inside sill plate along with busting away the inside cement ledge that holds this sill in place. That's for all that information, you are obviously very well educated at this. Are you referring to a screw jack ?