How to determine whether your crawl space really needs stabilization jacks

Question

I'm working on a roof replacement that insurance refuses to cover. Since I'm getting a loan anyways, should I just get a bigger loan to "permanently stabilize" (not re-level) the foundation (crawl space)? My tenants noticed that the kitchen floors are uneven, causing some separation between the planks, and my contractor (who installed the floor) says it's because the foundation is sinking, and causing the planks to separate. Would getting some hydraulic floor jacks intalled in the crawl space be a good idea? Alternatively, I could just leave it how it is, and eventually replace the kitchen floor if it starts to sag again. And if we tear out the entire the floor again, we could install some jacks under the kitchen floor at that point. There's only about 6 inches of space from the kitchen floor to the ground under the house, so it's really not accesible at all unless the whole floor gets take out, which we just did in April of 2024 for a turnover of the unit. Not sure what would be best, and would appreciate any advice on this. For context, the house is a duplex built in 1902. The basement contains a cellar where the 2 water heaters sit, and around that deep, 8-foot cellar is a 2-foot crawl space, excep under the kitchen where it's like a 6-inch crawl space.

Adam Tafel · Answer

I’m guessing your property is in Northeast?

The odds that your foundation is currently sinking is pretty low. Techincally possible, but the odds are very slim. I would have someone who is very familiar with homes in the area (another landlord?) walk the property with you - in these situations it’s key to get advice from someone who has nothing to sell you, no bias whatsoever, and experience with homes just like yours.

Homes will shift, expand, contract, etc - that’s why you’ll see the same crack continue to reappear above a window or door frame - but be very very sure before you start messing around with jacks/etc.

I don’t mind the idea of borrowing more while you have the chance for improvements, but have someone run a value analysis to keep from going underwater. Are there any value add projects you could cover with the loan which would net you a higher income after the new debt service?

Jim Johnson · Answer

With a 1902 property, I’d probably be careful about assuming uneven floors automatically mean active foundation failure. Older duplexes can have decades of settling, framing movement, undersized joists, moisture issues, or previous patchwork repairs that all show up similarly.

Before taking on additional debt for “permanent stabilization,” I’d want a real structural assessment rather than relying only on the flooring contractor’s conclusion. Especially since you mentioned the crawl space under the kitchen is only about 6 inches — that limited access changes both the feasibility and cost of any stabilization work.

The bigger question for me would be:• Is the movement active or mostly historic?• Are there signs of worsening structural issues beyond cosmetic floor separation?• Would stabilization actually solve the root problem or just reduce flex temporarily?

Hydraulic/support jacks can absolutely make sense in some older homes, but I’d want an engineer or foundation specialist to evaluate load paths and long-term stability before making that call. Otherwise it’s easy to spend a lot of money treating symptoms instead of the actual issue.

Since the floor was already opened recently, I’d also weigh the operational reality of how disruptive and expensive future access would be if things worsen later.

Richard F. · Answer

Your comment is the floor is "uneven"; and there is separation between flooring planks. You also state you took the "entire floor out" just 2 years ago, apparently exposing the floor joists, since you imply that you could place jacks under them if you removed the floor again.

1) Why did you not fix, or at least further investigate when you had the floor out the first time?

2) What type of flooring "planks" are separating? Actual hardwood tongue and groove? Or did you install subflooring, with "floating" LVP?

3) Define "uneven". Does the floor have multiple ups and downs; if you place a ball or large marble on it, it will always roll to one particular side of the room or a more central area away from walls? At one point you state that it "sags"...where? Or does the floor "flex" when you walk/bounce on it lightly?

4) You do not state what type of "foundation" there is, either in the water heater area or for the kitchen area. Also, is there a second story above either area?

5) Can you see the kitchen area from the water heater portion of the space? Specifically, can you see to the area of unevenness? Or to the area where kitchen plumbing is visible?

6) Can you post a link or pics of the exterior of the general kitchen area; the interior of kitchen; the floor with markups or indicators of exactly where the issue is; and whatever is visible from the water heater space?

If the issue is enough for a Tenant to complain about, it makes no sense to do nothing, if in fact there is a notable issue. Since it is in the kitchen area, my first thought would be structural damage from long time water leaks, either rotting the wood structure or subfloor. It could be as simple as weak subfloor and poorly installed floating LVP. If the issue is inadequate footings for the exterior wall of the kitchen addition, that is a bigger issue, but not solvable with a couple of jug jacks.

How to determine whether your crawl space really needs stabilization jacks

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