Cost, Time, and Skills:
This job took two people one afternoon. We got muddy because we were in a dirt crawlspace doing just that, crawling. We used 18,000-pound screw jacks, 4×4 lumber, a circular saw, power drill/driver, and cement blocks. Total cost was less than $200, while a pro would charge $500-$1000.
The Story:
This past Saturday, my brother had me over to help move some of his furniture during the annual rearranging of the tv room. The photo below shows what we saw when we moved the couch away from the wall.
Look for the 1 inch gap between the floor and the base board
Apparently, it’s been that way since they bought their 90-year-old bungalow and it’s been nagging at my brother ever since. You may have similar areas in your home. You probably feel the same way my brother did: “it’s not THAT big a deal and it’ll cost at least $1000 to repair, so let’s buy diapers and food and gas with our money instead.” Well, it isn’t THAT big a deal now, but it could develop into a whole host of problems down the line, especially if the sagging is caused by a larger issue.
Three 18000 lb screw jacks and solid concrete blocks for support
The truth is, it will cost you upwards of a thousand dollars to hire professionals to do anything to your foundation or the under-structure of your home. Just plan on that. Plus, it’s hard to find the right people to do this work, because it requires on-site problem solving and a certain amount of risk assessment (don’t hire anyone that seems kind of stupid). I know this. We paid to have some work done on our sill plate last summer and it hurt the wallet. A lot. However, watching the crew work on my house let me know that I could certainly do that work myself the next time the need arose.
We ripped the 2×10’s in half to make four 4 ft joists
As a homeowner with an eye for and interest in how things work, I’ve learned an extremely important thing: my house is actually really simply built and nothing in here is all that complex. The trouble is knowing what to do and what tools to buy. If you aren’t good at figuring stuff out on your own, hire someone. . . once. While they’re working, ask them questions about the process and about what they’re doing. Assess whether you think you can do it yourself. I learned most of my skills out of necessity (it’s a cash flow thing) and by watching professionals.
As with many old houses, my brother’s has a tiny crawl space door. I’m large so that makes me unhappy.
For this job, as with any job, we first needed to figure out what the root problem was. The sagging floor was the symptom, and somewhere under the house there had to be a cause. Well, after doing the navy SEAL crawl up under the house, we found that the joists that were supporting that floor were not actually attached to the sill plate any longer, as seen in the photograph below. This is an obvious problem, considering the fact that the sill plate is the first line of support above the foundation wall. You can see that the joist had dropped about an inch below the sill, explaining the inch the floors had sunk.
The joist had slipped about an inch from the sill
In order to lift this section of flooring back up an inch, we needed to purchase a few screw jacks, which can be purchased at your local big box hardware store for about $30 per jack. The ones in the photos above are actually not the ones we ended up using. We had to buy shorter ones. But hey, what’s a home improvement project without at least two trips to the store?
Moving around under old houses can be tricky. My brother’s crawlspace opens up quite a bit once you’re inside. It used to be a dry cellar for storing produce during the summer, with a trap door in the kitchen.
As you can see in that last photo, my brother’s crawl space is rather spacious in spots. Unluckily for us, the spot we were working wasn’t one of the spacious ones. Here he is squeezing through the little trap door. Note the coveralls. I’d recommend covering yourself when working under the house. It’s nasty and there are spiders and junk.
A gift my brother and I both possess: flashing a goofy smile at a moment’s notice.
Here’s where we were working. The 2″x8″ joists you see in the photo (the boards running from left to right above my brother for the lay men) are the ones we would be supporting. We decided that we wanted to sister a new 2″x10″ board up against the existing joists and support the new joists. We chose this method because of the small amount of old termite damage we saw in some of the old joists. What we did was lay the new board flush with the floor boards and with the old joist. We then fastened the two boards together with 3 inch wood screws.
The crawlspace was really tight in the area we were working. Luckily, it was pretty dry. The vapor barrier and outside drainage had done their job well.
Below, you can see my brother prepping one of the new joists by partially driving the screws into the wood. This is surprisingly difficult to do when holding a twenty pound joist and a drill above your head while lying on your back.
I used to balk at the drills and power tools that come with a light. Not any more. That little light came in very handy.
With the mud and the muck, I didn’t get any photos of the next step or two. In the photo below, you see the final product. You can see how the new joists are attached and, if you look towards the background, how they overhang the old joists so the support beam is only pushing on the new joists.
Here’s the completed job. The new joists are attached to the old joists and are supported by the 4×4’s and screw jacks.
Once the new joists were up, we found locations where the concrete blocks could sit flat on the ground so the pressure wouldn’t cause them to crack. After they were in place, we hoisted up the 4″x6″x8′ beam so that it crossed all four of the new joists, sliding the screw jacks underneath. With the beam resting nicely on the jacks, we slowly turned the red handles until the beam was in contact with two of the joists. Then we kept turning until it was in contact with all four of the joists (the lower two lifted up to be in line with the higher two). By yelling through the floor to my brother’s wife, we were able to coordinate our slow turning of the screw jacks until the crack between the floor and the base board was gone.
Here’s the final product. Total, this job cost my brother $150-$200, where a pro would easily have charged $800-$1000. I’ll admit, this is probably not the job for a first time do-it-yourselfer, but folks with a little experience and confidence can easily repair the sagging floors in their homes.
Look for the 1-inch gap between the floor and baseboard. It’s not there any more.
The before and after is below. If you’ve got questions or comments, leave them below or contact us at oldhousecrazy@gmail.com. Also, feel free to leave us a comment on our facebook page www.facebook.com/oldhousecrazy. Thanks for reading. -Robby
Before and After
Old House Crazy 
I am so impressed with your knowledge and skills. Who’dathunkit?????
Wow, nice post! Plenty of pictures to get the idea across, thanks!
Thanks to “The Bennetts”. I have a log burner and stone hearth and there is an emerging gap between the architrave and the boards, and worse, the chimney attachment to the top of the burner has nearly popped out because of the quarter inch drop. I am in Australia, so my screw jacks are about three times the price, but I will be tackling my problem in the same manner this weekend. Thanks heaps.
So the floor jacks stay permanently under the house from that point on then? My wife and I are looking at buying an old house and sagging floors is one thing I’ve noticed on the edge of the ground floor rooms.
I’ve got jacks under every room of my house. Most of them were there when we bought the place. When old wooden homes were built, the floors were not supported as much as they should have been for 100+ years of use. I guess they just didn’t expect the house to hang around that long.
No one had quartz or marble counter tops and multiple heavy appliances. That is the difference.
You don’t have to leave them under there permanently, what we’ve done in the past is you use two regular jacks with blocks instead of the floor jacks, then put in a stack of cinder blocks (with the flat blocks or a dug and poured concrete pier beneath them) and then a couple wooden blocks on top (they’re needed to get the height right as well as to help spread out the force so that you don’t crack a block)
I’m about to start a similar project… but I read you should dig a hole and put cement on it to build a strong footing rather than using a cap concrete block… Wouldnt your cement blocks sink over time due to the weight of the house pushing down?
I agree it is probably better to dig the hole and pour cement if you’re lifting the house a lot or if you’re only using a single jack. I think we’re fine since we used multiple jacks and we were really just redistributing the weight.
If they sink, we can go back and tighten them up, or pour a pad like you suggested. Thanks for reading.
This response just saved me a ton of time and effort. I was going to fill several holes with concrete, then wait for it to set, etc… Never thought about the fact that I could simply re-adjust the jacks every year or so! Thanks for doing the thinking for me.
I’m doing a bathroom reno and the floor sags at least a good 3″ along the rock foundation barrier wall and its a very old place cellar basement, has a 4’10 support beam on either side, and floor boards are rotted out whats your suggestion that’s the smartest,cheapest,and safiest way I should go ahead with it? the worst of the sag is where the toilet sits and the tub,but worried about causing more problems when beginning to raise it?i was thinking digging a couple holes pouring concrete,screwing 2 2×6 together to run across from the one side and the same off the other side a couple feet apart.then again a couple holed with either poured concrete or blocks,and a 4×8 across them 2 2×6 joiststs and raise it a couple inces and sister either sides of the old floor boards until it sits level??
I’ve been jacking houses since helping my father when I was 10 yrs old. Good catch on the concrete block. That is a big no no. Those concrete blocks are not meant to carry that brand of weight.
What method would you recommend for repairing the sagging floors?
Thanks for helping us save a pile of cash!
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will jacking up the sagging floor in our crawl space fix the sagging roof problem, its all in the same area of the house. thanks Jean
It might. I’d suggest looking at the joists under your floor and then get into the attic and check the roof structure, looking for sagging or other abnormalities. If the floor is sagging, bit there is no noticeable snagging in the roof, it could just be the floor. If unsure, have a pro come out and inspect it and give you pointers. You may pay a few hundred bucks on the inspection, but they might convince you that you can do the job yourself. Good luck.
The screw jacks used shown in your pictures seem a different brand product, not the Akron ones shown in your second image — I bought the Akron screw jack, it won’t turn higher due the screw base will turn also. What is the brand of the screw jack you finally used?
I googled Akron screw jacks and what I found seems very similar to the Tapco brand jacks shown in these photos. I think that either brand will work, so long as you purchase the correct height. During one of our trips to the hardware store, they only had one size, so be sure to measure the height of your space and buy jacks that fit within that range. I can’t say for sure, but I think your jacks are too short for your space.
Maybe the early made was with turning bar insert through a hole as shown in your image. I bought the adjustable floor jack 2 ft 10 – 4 ft 7 height, multiple pieces to assemble. And I also looked at the shorter ones, not like what you showed here. Tapco brand is sold in Home Depot, very similar to Akron brand which is sold in Lowes, but they do not look like the ones shown in your images.
I googled and found Ellis brand heavy duty steel shore jacks look more like it. But they are out of stock for the size I want.
Both Tapco and Akron should have designed with a notch-lock mechanism between the screw plate and the inner pipe that stops the screw plate turning when the screw is turned.
I just learned that we have this problem too! I am nervous, but we are going to fix it ourselves. I am so thankful for this site ! I kinda know what to expect now! Thanks again! Wish us luck!
Thanks for reading, Penny. Good luck on the repairs. If it gets too crazy down there, don’t be afraid to call a pro for a consult. They can always give advice on what they’d do, even if you don’t hire them to complete the work. They might charge fifty bucks for the visit, but sometimes that’s worth the advice.
I have the same sag but the beam is 3- 2×8`s nailed together and the sag is about 3 inches in the centre. Does anyone know if I can push up the same beam with the jacks now that it is warped?
Good job!! I have a similar situation. I wish there was a way to attach a picture or two to this post.
Wow! That is a lot of sag. Obviously the beam is undersized, for that to have been installed like that shows inadequate knowledge of safe building practices. You need to get an overall assessment of foundation and support structure from a professional, urgently.
What’s your thoughts on an older A frame cabin, that drastically needs to be leveled due to the ground being sand and no foundation, just sitting on cinder blocks (for around 40 years)?? Warped floor joists, of course! My husband (the know it all handy man) wants to tackle this one on his own, I do not doubt his skill however, I am afraid of more permanent damage being done to the structure if something goes wrong.. PLEASE need your thoughts/input!! Thanks!!!!
Depending on the geographic location is dependent upon the method, procedure for fixing sagging floors. When pouring a concrete footer/footing the depth of the hole is dependent on the the frost line. For instance in Michigan the footing probably has to be 4ft where as on the coast in NC maybe 18in is required. I would check out building code requirements from the building code inspector. Or get a detailed estimate from a local contractor. I know locally a company uses high pressure foam to level house and they are expensive!! A friend of mine paid it more than $45,000.00!!
It’s best to take it slowly when lifting any structure. A 1/4-1/2 a day if you are doing a whole house. Remember, pipes stress too after they have been in a position for a long time. Do your homework.
My mother’s ranch style house also is built in an area with a lot of sand. Her support beam has a crack all the way through, likely due to water damage and stress. Will concrete footers need to be poured – how far down should they be set? Did you need a permit in your area for this job? Is a wood beam under the house better than an I-beam?
Those are really great questions, but I’m not sure I have answers for you. I do know that if you suspect water damage is the cause, you need to make certain that the leak is fixed before you repair the damage. As for the beams and footings, I recommend you have a few pros come out and assess the structure. That’s what I’ve done in my crawlspace. Most will come for free and will be honest with you. If what they describe seems simple enough, do it yourself. If not, hire someone. The job described in this post was pretty simple, so we had no trouble doing it ourselves.
ANY SUGGESTIONS ABOUT DIGGING PIER HOLES , I HAVE HEARD THAT DIGGING A 18 INCH HOLE AND PACKING BASE MARTIAL IN IT IS BETTER THAN CONCRETE , BECAUSE THE WEIGHTED CONCRETE WILL SINK , WHAT ARE YOUR THOUGHTS ?
Thanks so much for the article. Exactly what I was looking for. Same here on a 90 year old home (1922).
How do you figure out what size of jack you need? I’m looking to raise my sagging wooden floors and the height of my basement is 7 feet. I’m just unsure of how much my house weighs and I don’t know how much weight I need the jack to hold. Is there anyway to calculate it?
That’s a great question, Kristan. I actually don’t know how to calculate the weight of a home. I bought heavy duty jacks and assumed that they wouldn’t be fully supporting the house. Remember, your home already has support, so you’re not supporting all of the weight. You are simply adding support where there is a lack.
However, if you are still concerned, you can ask a structural engineer in your area to estimate the home’s weight and make a recommendation on jack type.
The house you where repairing was built using balloon construction,The exterior walls sit directly on the foundation wall and the floors float.That is why only the floor dropped instead of the entire structure.You were lifting just the weight of the floor.Most ranches and two stories built in the fifties and after were built using platform construction where walls sit on top of the floor joist that sit on foundation wall. In this style framing the entire structure will sag in that area usually causing cracks in walls,ceilings or doors rubbing their frame.You will need a proper footing under the post jack because your lifting much more weight.If your correcting a sagging interior floor in ether style framing locate the main support beam in that area [the large beam that the floor joist are sitting on] raise that area.Keep in mind if its drastic have the foundation evaluated.
the house we just purchased as a crawl space. The foundation is stone and needs some repair. The main load beam is cracking. The joists have been notched out a lot to sit over the main beam.
Deep enough that there is only about 4″ difference in height between the beam and joists (Obviously this weakens the joist).
It looks like the outside walls rest on the stone foundation.
My thought is to first sister the main load beam with 2 x 10 boards then support it with several jacks. Next sister the joists for more strength.
My question is: would I use joist brackets to attach the joists to the new main load beam.
Basicly it would be like building a deck.
The new joists cannot sit on top of the beam without raising the whole house.
We intend to do this after removing the floor boards and working from above and below.
If you can understand my description, what are your thoughts.
Many thanks
Great post! Finally information I could use. (And yes, my old house is driving me crazy too!)
I have a feeling I’ll be back for more help. Thanks.
I need someone to do floor joist repair for me any suggestions also what will this cost
Another technique is to purchase ready made pier blocks 12″x12″ ($3 each) with the small hole predrilled for simpson 4×4 adjustable post supports.($10 each) This allows you to attach any 4x material with nails or screws and the simpson post support which then can be jacked up like a screw jack up to 2.5″. I used this technique to support a similar issue in my house.
What would you do if it were un upstairs floor that was sagging? Leaving jacks in the middle of the kitchen and living room wouldn’t really cut it and I’m not sure how to deal with that.
Hey Kristin. I’m really not sure. This job was pretty simple. It sounds like your job is more complicated. Sorry I can’t help.
No problem; thanks for answering so quickly!
How far apart should the jack’s be placed?
Hi, there. When you talk about hiring “pros,” what would this be a structural engineer, basement company, etc.? We’re experiencing significant floor sagging around the edges of the house, and I’m at somewhat of a loss of whom to call, as we live in a small town. (We have the added misfortune of having a super small crawlspace height-wise, so jacking things up will likely require some removal of floors.) Thanks for any ideas of the best types of companies to call.
A structural engineer would be great, but an experienced home builder or contractor should also be able to make recommendations.
Structural engineer is the way to go. Expect to pay $300-500 for the inspection and report, but is the best way to do it. It will save you time and money.
If you have sagging around the edges its termites/dry rot in the rim joist, jacking doesnt fix that.
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My older home is lower one side front to back ,and in the middle Quarter inch side to side…I’m built into a hill…seems like a long term sagging from water wash off mountain damage…crawl space is only at the most 24″.
I have to redue kitchen floor due to water damage not taken care of…
Will it be easier for me to dig down into grown and resupport from inside ,replacing with new sub floors ,than trying to crawl under and struggle..??
I know this article is from years back, but from a leveling perspective, I guess you just eyeballed it? Technically, it’s not an old house (1989), but the builder built it wrong, and there has always been a hump in the floor of the kitchen (and what might be a sag where the refrigerator is). These appear to be related to the original footings and support – the floor is just not level.
Back when hi-end flooring was vinyl, you could get away with this. 21 years later, I want tile in the kitchen or possible hardwood, so the hump has to be resolved. Ant recommendations for measuring this unevenness?
thanks
Hey Charles. I’m really not sure. I’d recommend having a contractor come out and give suggestions based on a visual inspection.
We have this problem. Our house has the heat in the floor and I don’t think the contractor knew what he was doing when he poured the concrete over it. Our floors are all tiled, so it added more weight. We have had a company called Fivestone Foundations come and do a lot of work…….putting in new joists, though I’m not sure all of it was done. They did what they call encapsulation. I think the cause of a lot of the problem was water standing under the house. Sump pumps were installed and a dehumidifier. The problem is, we are having a problem getting them to come back and finish the jacking. This has been going on for six months. The owner was here last Friday and promised he would be here Wednesday, Thursday and Friday this week……needless to say that hasn’t happened. We made the mistake of paying them and not holding out some until the job was done…….never again! My question is, would you be able to find us some help getting this done……..we don’t know who to turn to. We live in Marion, Kentucky which is about 4 hours from Louisville.
we need to re support our floor with floor jacks and sistering.It is over a very small or low crawl space.would it be O.K. to take out the whole sub floor to do this work. Our house was built in 1860 in Indiana.
I’ve heard of people doing that before. Good luck!
What state do you live in? Im in algonac MI and im in a 100 year old trial!!! If your in the area my crawl cloaned your before pix
We’re in Georgia, just outside Atlanta.
A little north honey. Where the mitten snags on bottom of thumb
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Very interesting article. Was great to see how this is done. My situation involves an upper unit with a pretty steep deflection (up to 1 inch over 4 feet in one place). There is obviously no crawlspace underneath my floor because there is a condo unit (first floor) there. I plan to hire a structural engineer and pay for his expertise/report, but my reluctance is based on how little he will be able to see/evaluate being there is no foundation directly below me, no crawlspace, and no way for him to view joists, etc. Would he need to remove a wall or remove my wood floor? Any idea?
Those engineers are able to see signs and read clues in your structure that you and I cannot see. Have one out to your place and see what they think. They might need to pull up the floor, but probably not.
Things like this make the Internet so priceless. Thanks so much for all the work it took to document this! Buying a house is expensive enough. Maintaining it as a DIY man is necessary for me (it’s a cash flow thing). Your effort is so encouraging to people who don’t have a couple of grand to spare.
I have a sagging floor, but my house doesn’t have a solid foundation, it is on what is called pier blocks. So, I’m not sure if the same solution would work. Any suggestions would be helpful.
Thanks for the info! I used these screw jacks from Ellis on my dads house. They worked great and are VERY heavy duty. https://ellismanufacturing.com/collections/related-to-light-duty-steel-shores/products/light-duty-steel-shores-w-o-bearings
Great post, and great pictures! I have a house with a similar looking crawl space and similar floor construction – maybe because my home is of a similar age in Atlanta 🙂 Were you able to get the original joists back on the ledger, or did you just let the sistered joist take the load? I ask because some of my joists are doing the same thing.
Screw-type jack posts are only for temporary support and concrete blocks should never be used.
Code requires 3.5″ lally columns with 6″ top and bottom plates. The posts must each be landed in the center of a cast concrete footing. Each footing must be 18″ x 18″ x 9″ deep. The footings must include a minimum of 2 levels of crossing pairs of #4 steel rebar in the casting.
Home inspectors will pick up on this when you try to sell your house.
After jacking up the sagging floor, how does the floor stay up? Is this something I would have to do every few months to maintain the floor?
The crawl space at our house is very shallow and not really sure who could fit in there. Is it feasible to go pull up the wooden subfloor boards and try to fix from on top?
I have no knowledge of that type of work. It sure sounds possible.
i need help fast, the hole kitchen floor has dropped its sitting on my pipes and there is black mold growing under the floor
You need to hire a pro. Black mold is no joke and DIY jobs are rarely fast.
Looking back on this project, do you think there is any benefit to jacking up the beam to a correct elevation, and THEN installing sister beams? (vs installing sister beams and then lifting). Not meant to as criticism, but as advice).
As a licensed professional, I can tell you that what you did is merely a band aid. Every now and then you will notice it sagging and will have to periodically crawl in there and adjust those jacks., over and over again. The praise you’re receiving for what amounts to a “hack” job is an insult to my profession., You are truly arrogant if you think you know how to do what I do simply by watching a pro once. Thats a joke.
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My sister has done the floor jacks. She lives in a flat county with poor run off. Water has caused jacks to fall over, so best support possible and annual checking is good. Maybe cheaper to install a camera… than pay for pier and beam replacement. Easier than crawling and could check as needed. Or, send a drone in! Not saying I could do those things easily, but could be good. I had to replace a foundation years ago in the 1990s. Got a good deal, pier and beam, done right. Price tag 8-9 thousand.
Great article!!! I googled for hours and your pictures and explanation were perfect and easy to understand!
I’m going to try and do this to one of my old rental homes. What size were your Hydraulic jacks? I’ve read some used several 4 tons then some that said to use 20 tons.
Thank you. This was the BEST written set of instructions I’ve ever seen on this topic. You guys ROCK ✊
Question: We purchased a nearly 100-year-old commercial building with approx. 7.5′ ht. floor to ceiling full basement. We find one area of the upper floor to be saggy and want to lift it. Where would begin? We are on an extreme budget as we are using our own funds for the community project that we bought the building for, Any help would be appreciated! Thanks and God bless!
Suggestions appreciated for my front porch that was built with no foundation. The house was built in 1895. The porch sags on one side Thoughts? Can you help? S.O.S.
Suggestions appreciated for my front porch that was built with no foundation. The house was built in 1895. The porch sags on one side Thoughts? Can you help? S.O.S. Thank you.
I own a older home the walls in basement are bowing it leaks and are cracked.
Pro tells me did be around 30.000 can you advise me different. I am a widow of 65 on fixed income from Gov cannot afford this..
Thanks ; Teresa
What if I cant get under my home crawl space is too low my floor isnt showing signs of separation instead my room slants downwards to the point its causing gap around the ceiling and wall and my door frame has a 1 inch gap I’m a have to tape up now
That’s a tough one, Foster. I imagine you’ll need to call a professional or try to go in through the floor. We had a similar situation in our front room and it was caused by rotten and termite damaged sill plate. It was more work that I could have done to repair it.
We have a floor joist that is tipping, or rolling. My husband’s plan is to use a long 4×4 perpendicular to the joists, jacked up to release the weight on the tipped joist, straighten that joist, then sister a 2″x 12″ x 12 ft to the newly straightened joist.
Did you leave the Jack’s under the house. We’re planning to just for extra insurance. If you left them, don’t they need more of a footing than just a concrete block? Thanks
We did leave the jacks under the house, and my brother did go back under there to tighten them later on. Larger footings would have been better.
Great post and pictures!