sagging floor

[Mark Stewart]

In this house I bought the floor is kind of sagging the basement was doug after the house was built. probably 1935 or so an 1st floor sitting on old wooden post. These pose are in meed of replacement. I have floor jacks and cap blocks toset them on. Any words of wisdome befor I start this massive undertaking? All suggestions carefully considered in this matter.

Thanks Mark

 

[Gotcha6]

Crisscross the cap blocks & use a single block on top. Set them on washed stone that is level. You stand a better chance of not breaking the cap blocks that way.
Better yet, use the porch post blocks they sell @ the BORGs.
Take you a bottle jack & 4 x 4 timber to do the heavy lifting. Those post jacks aren't very easy to raise loaded. Be sure to set a horizontal block of 2 x 4 (preferrably SYP & not spruce) between the 4 x 4 & the bottle jack - and set the bottle jack on a broad firm base itself.
Be sure & anchor the jack plate furnished with the jack post to the sill.
If you plan on living there long paint the post with a Rust Oleum type paint & oil the threads with spray Lithium grease. You'll have more settling later.

 

[Mike Davis]

You didn't say how much sag you have. But, if it is more than an inch don't raise it all at once.

Jack it 1/2 inch and let it sit a day or two, that lets the walls and the rest of the floor adjust. Then raise it another 1/2 inch and let it settle another couple days.

It will take a week or two to raise it very much but that will save you a lot of cracked walls and broken floor boards.

Go 1/4 inch too high and set your permanent posts. It should settle in and be just right for a while.

If you have room and time go ahead and dig footings at least a foot deep and pour concrete footers to set the permanent posts on.

 

[Dudelive]

You have gotten 2 darn great replies and they will work. One thing that I did before in a similar situation was as mentioned by Mike was raise a little at a time, for me I listened to the "creaking" and added a little more and then waited 3 - 4 days and raised some more till it "creaked" again and added a little more and waited again.

For me I was raising a ceiling where someone had removed a load bearing wall and the ceiling had settled about 2 inches in a 20' span. So raising a little at a time will work and won't crack the walls as long as you go easy. It took me about 3 weeks to get it about 1/4" over level and then it settled to just right.

Go easy and be patient

 

[Glennbear]

As a result of the report by the buyer's inspector when I sold my house in NJ I had to undertake a similar project. I echo the sage advice given about slow lifting and sturdy bases. I would just add that you might consider adding wood "sisters" to the beam you are jacking with through bolts since the original beam may be undersized by today's construction standards. A lot of time the problem is compression of the wood fibers over decades of use and fresh lumber helps. :wsmile:

 

[CrealBilly]

my word of advise... Make sure your joists you are jacking are firmly secured to the outside bands, use steel plates if you have to. Go slow on jacking (day's / weeks), go a little higher than needed, then sister the joist. You may not need a jack after you get the sister good and secure, But if you do, follow the great advise given here by those who have been there and done that.

Personally I like set a porch post block on a hole filled with grade 9 (3/4" chip stone with packing dust used for driveways) and treated 4x4's to hold up a sagger. Grade 9 will setup almost like cement because of the dust.

 

[scsmith42]

One thing that I did on the last house that I leveled was to use a laser level to take readings on the floor above every post / pier, and to make a map that depicted how much that I needed to raise each point in order to for the house to be level when I was done.

I then pre-made a set of shims for each pier that I could add as needed over the few weeks that it took to allow everything to adjust.

Worked out very well and eliminated a lot of work once I crawled under the house.

 

[Mark Stewart]

Well I found out today I got some joist to replace. If I get that donr then Ill have to buy new post what to buy for permanant post is the question. I have been told that I can leave the jacks as post if I want that they should be fine. My question is is that true? Thanks for all your help

Thanks MArk

 

[Gotcha6]

You may leave the screw posts as permanent. Cosmetically, it'll look like mud on a white wedding dress, but unless you are willing to add a large support pier, structural steel column, & beam system it's the way to go. You should mind the spacing and lateral supported area for the posts so they aren't overloaded. We'd love to see some pics of the problem before you start. It may help us visualize the solutions available.

 

[James Davis]

You have been given some very good advice. One thing that I have found in . heavy loads with bottle jacks is that it is a lot more stable if you sit the jack on top of the post. It gives the jack a bigger contact area with the movable post and a solid anchor where the small end of the jack is.

I second the idea of digging and pouring footings for the permanent posts. Even if that means cutting out the floor and repouring the spot. The screw jack post can be left for permanent. If looks if questioned by the Mrs. just build covers for the posts but leave an access to the screw so that you can get back to it and make the adjustments that you will have to make. I would also put at least a 1/4" steel plate above the permanent post just to be sure they don't impale themselves through the beam.

Another thought that I had,was if headroom is not an issue, build a new beam underneath the existing beam and jack them both into place at the same time.

Some random thoughts on Saturday night.

James