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Sagging kitchen floor

11893 Views 14 Replies 5 Participants Last post by  csaag
40 year old split level house. We've been in it 15 years but didn't notice this until we had an old addition removed & expanded and the kitchen redone where we pulled out the old vinyl flooring and countertop & replaced with a tile floor & silestone countertop. The addition was done 1st, later when the kitchen was pulled apart I noticed that around the sink area the floor sagged compared against the beginning of the addition. Maybe 2 inches at the worst part. Now we've noticed the floor tiles around the sink area coming loose. I'm thinking it's because the floor is sagging a little more with the extra weight of the new kitchen floor/countertop etc.

Below the kitchen is the basement - 8ft high with cinder blocks wall. Floor joists are 2x8 spaced 16 in apart running from the front yard to the back yard. They extend about 3 & 1/2 feet past the cinderblock wall. Above the kitchen is the attic.

Last summer I went in the crawlspace under the addition and underneath the part where the floor joists extend, I dug 3 holes in the center of the space, 4 feet apart and about 2 feet deep and fiiled them with concrete on which I put a pair of cement filled blocks and a pair of pressure treated 2x6s. Mainly for peace of mind to help keep it from sagging any further. But that area just stopped short of where the sink is where I notice the most sag. So I was thinking of going back under to do the same thing in the 6 foot span next to where I left off.

Is this doing any good to help prevent further sag?
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What is the unsupported length of the 2x8 floor joists? And are they full size 2x8, or the more common 1-5/8 x 7-1/4 inch joists?
If you have the room, glue and screw 3/4" plywood to the bottom of the joists. This will in effect create a box beam. This should help distribute the load over a greater area and lessen sags. Any areas where you have excessive weight, like the cabinets or refrigerator, you should sister another 2 X 8 under those joists first.
are there cracks in the basement floor and walls? 2" inches is a lot. 2X8 with a mud floor, tiles and a heavy counter top is pushing it.

you really need an engineer on this. your attempt with 2' cement piles wont do the job IMO. A small deck gets four foot piles, inspected fist before poured.
Get an engineer and save your home instead of band aids. This can be fixed as a DIYer but get a pros advice first.
thanks for the replies,

I believe the floor joists are 1-5/8 x 7-1/4 inch. They're definitly not 8 inches I'd have to measure it tonight.

The distance from the cinder block wall to the post in the middle of the basement that hold 3 2x12's is about 10-11 feet.

The kitchen components that sit at the backwall are a 5foot long countertop, the cabinets above it, the sink, and a standalone pantry.
The frig and stove are not an issue.

There are no cracks in the basement walls/floor. It also is not a mud floor. The contractors that did the kitchen put some type of board over the subfloor that the tile sits on.

This may be a dumb question, but if Iwere to get a pro's opinion, exactly what type of engineer do I look up? Is there a 'structural engineer; klisting in the yellow pages?

The crawlspace from which the cantilever extends into is about 2 1/2 tall. Hard to work in but there is room to crawl around and inspect things.

Again,thanks for the replies.
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Photos would help immensely to help understand your problem!
Here's an attempt to upload a kitchen and basement photo. I apologize in advance for the mess that is my house!

A) the basement floor joists measure 1 5/8 x 7 1/4

From the kitchen photo, the cinder block wall at the end of the basement lines up about 1 foot past the kitchen island.

The kitchen is ~20 feet wide, but the sag is deepest at the sink which is about 6 feet from the corner and in about the middle of the section that runs from the wall to the end of the pantry.


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I cant believe a 2" sag has no visible evidence in the supporting walls? Makes e wonder about some things. Is the counter top out of level? Theres got to be some kind of visible proof. 2" inches is a lot
I cant believe a 2" sag has no visible evidence in the supporting walls? Makes e wonder about some things. Is the counter top out of level? Theres got to be some kind of visible proof. 2" inches is a lot
Agreed.. maybe a broken joists or broken level?
I don't know the actual extent of the sag. It was noticable when the old kitchen was removed and you could see the difference between the end of the kitchen floor under what used to be the old cabinets/sink and the start of the addition floor. Could be the sag is 1 inch rather than 2. I do know when they installed the kitchen cabinets (the part under the countertop) that they added some wood at the base so it sat level and they screwed it into the wall joists so it was installed level.

It is noticable as you walk from the kitchen island to the sink. It's hard to show in a picture. Although if you look at the attached, which is the left wall of the kitchen moving towards the pantry you can see the growing gap between the tile and the addition flooring.

I have gone into my basement and shined a flashlight into the cantilever area and haven't seen cracked joists. Underneath the addition, the joists are covered by what may be 3/8 inch plywood so I can't inspect them from there.

I asked the contractor who did the kitcken/addition what he thought about the sag. Maybe as he was almost finished the job and didn't want to get further involved (just a guess) he said that the house has survived this way 40 years so it may not be a real problem. He said it never should have been built that way and they probably should've doubled up onthe 2x8 beams.

I'm wondering if jacks can be used in the crawl space under the addition to get it backto level and then maybe some extra 2x8's can be slid in from the basement and sistered to the existing beams?

Maybe because I'm aware of the sag it just sits in my mind. I am thinking about what someone said here and hiring a structural engineer to inspect it and let me know how much of a problem I have and what types of solutions are available. But I've never done thta before and not 100% sure how to go about it - just go in the yellow pages under engineers? I'm assuming having someone just look & analyze it wouldn't be a huge expense.


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are the corners around the door and window openings cracked? Are the cabinet doors unable to close? Is the counter top out of level? If you answer yes to these, than jacking the floor is OK because youre going to have to fix everything anyway.
If you answered no, then once you jack the floor, guess what will happen, all of the above plus windows will bind, doors wont close and maybe even a roof leak. Is there stuco on the outside or brick . . . you get the idea.

Shimming cabinets is very normal. Cabinets & counter tops have to be perfectly leveled and as far as the floor, I think your chance to have that perfectly level has passed when the kitchen was added and gutted. That was your window of opportunity. To do it now will be hugely expensive. (but possible)
I would only monitor the situation at this point. No need for an engineer since it is too costly to fix as it is now unless it becomes unsafe. (not likely). Sister any joists under areas that have the cabinets over them as much as possible to help prevent further deflection. This will help with preventing any tiles to crack. To fix you need to remove the tile and the cabinets, so forget about it!! If over time you see excessive movement and nothing is noticeable with the joists (as it is not in these pics), it may even be the foundation wall or footer under the posts that are sinking. This is why a structural engineer recommended by the building department or a realtor will be needed. I suspect you will never need this.
thanks for all the info.

No, currently I have no issues with opening cabinet doors or the counter top level.So thank you for the point about what could happen if the floor was to be jacked up now.

<Sister any joists under areas that have the cabinets over them as much as possible to help prevent further deflection.

Just so I'm sure on this, would this be like what I mentioned before? Go into the basement and slide a 2x8 next to a current beam as far back as I can get it into that cantilever area then bolt or nail it to the adjacent joist? I do have a joist close to the sink that doesn't have wires going thru it that would be good for a 1st attempt.
Yes, you have it right. This is what we mean by sistering the joists.
UPDATE for anyone still around:

Today I went in the crawlspace and the old addition cinder block foundation runs under the cantilever (I have no idea how deep those cinderblocks go) . On one end the plywood that covers the bottom of the cantilever pretty snugly, but the other end has a gap that runs from 1 1/2 inches at the base and 1/2 inch at the end. I was thinking of filling that gap in with cement.

I dug a 4 ft level into the ground until it sat level and measured the distance from the top of the level to the plywood that covers the bottom of the cantilever beams. I measured it at the base , 1ft from it, 2 ft from it, 3 ft from it & at the end (41 inches from the wall). I did that for most of the joists. At the worst there was an inch gap, but most of the beams showed about a 3/4 in gap. Turns out I also used 2x8's, not 2x6's, for those piers I put under there last year.

QUES: About sistering in 2x8's (about 10 ft long) in the basement. I could just try and hammer it in as deep as I can get it, but I don't want to force the floor up above and risk unleveling the countertop etc. But since I have an idea of the sag for those 41 inches past the end of the basement foundation, should I cut off a small triangular region from the top of each beam based on my measurements so I could get the joist all the way to the back of the cantilever?

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