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I am renovating an older home originally built in 1919 and added onto in 1949. The roof is rafters running in a T shape. So the load runs solely to the exterior walls with the exception of where the older house and the '49 addition meet. The house is completely gutted, I even removed the second story floors. I am going to dig out and put a new full basement under the house which is 21'x 32'. How big and how many beams do I need to lift the entire house? I consulted an engineer at justanswer.com and he said 8 beams. Beam size for a 12-inch lift: 5.07 inches wide by 10.13 inches high. No more than 8' apart. Also, can I place the jacks within the dimensions of the house? I've got both sides dug up and big holes there for new additions on both sides. Being fully gutted, I don't think the house weighs more than 20,000-25,000 lbs. The roof was estimated at 6,000 lbs. I've got 16 12ton jacks.

Edit: So I'm getting an estimate today for lifting the house and digging a full basement underneath. I will share the process here if we are able to afford it.

The drawing is my proposed new foundation with beams supporting the original footprint.

Edit 2: We got 2 estimates. 1) $13,200 2)$13,500 We are going to wait until spring since the timing put's me building a block foundation in mid-December in northern Wisconsin. I also hired out for sizing the beams to rest the house back on when the foundation is ready. I didn't expect the project to go this deep but thanks everyone for guiding me to professionals when a youtube video or public forum just doesn't have the answer.

proposed new layout

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    I'm genuinely concerned that somebody could be killed during this process. Do you have hydraulic power units to power these jacks remotely? Or are these hand powered jacks with people working within a couple feet of them?
    – popham
    Oct 17, 2023 at 2:08
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    Any beam sizes would be predicated on support locations. I don't know what "t-shaped" rafters means. Why don't you just replace chunks of foundation in sections 8ft wide or 12ft wide or whatever width wide?
    – popham
    Oct 17, 2023 at 2:12
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    If you ask a local general contractor, they can refer you to an engineer. Though it sounds like you should have started talking to one before you started the project.
    – keshlam
    Oct 17, 2023 at 2:21
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    Contact some of those companies that lift and move houses, they will know exactly what equipment and beams you will need. This is not a job for a cowboy or "redneck" cheap solution.
    – Solar Mike
    Oct 17, 2023 at 4:55
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    Do you actually want to change the house's elevation? Or is the jacking just to facilitate work? What is supporting the beams while you do all of this work?
    – popham
    Oct 17, 2023 at 5:36

2 Answers 2

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I will join the chorus of people telling you not to do this, but I'll answer your question to give you an idea of what you are facing.

First, I understand why you don't want to call a house moving company. Unless your house is in a place where the house is worth > $2M as is, it's usually not worth it to pay these specialist companies to raise it, as they can charge more than the structure is worth. It might be worth paying if the house is worth a lot and the house is grandfathered in an otherwise unbuildable lot (frontage, offset, minimum lot size, minimum house size, etc.), but I'm going to assume that's not your case.

I also see in your comments that you are not talking about lifting the house 15' in the air and building under. What you are asking is about holding/bracing/shoring the house in place, perhaps few inches above the current level, so that you can bring in a mini excavator and remove the old foundation, set your forms and do a pour.

The way you do this is by using railroad ties perpendicular to the joists, then use cribbing under the railroad ties. You lift the house a little bit, then put the cribbing (pieces of 4x4 or 6x6) under the ties, making a square pattern, where the weight of the house is always compressing where the pieces of wood meet. The cribbing goes on where the basement is, that is, inside of the house perimeter, and they support all of the joists in a way that you are not introducing any new forces to the house: the house will still be supported as it is now. You do not use manual jacks for this job, but hydraulic jacks controlled by air pressure. You then connect these jacks to a manifold of valves, which you control from a safe spot where the house can't fall on you. The idea of cribbing is that if the jacking fails, the most one side can fall is 3.5", which prevents a total collapse, the house tipping, etc. It also allows you to get under the house safely, as you are not relying on a bunch of jacks not failing/tipping/sinking, but you are instead relying on an array of cribs, 8, 10, 12, 16 cribs, whatever, to hold the house. And you are never under the house while it is being lifted, you only go under the house after you lift, wait out all of the creaking noises, and only for a few seconds to lay an additional pair of 4x4s. Again, even if the jack were to fail while you are under, the house can only move 3.5" and only on one spot.

I've lifted a few houses and pretty much every old house I work with requires some foundation repair, which in turns requires a bit of lifting of the house to correct some leaning/sinking etc. I am telling you that there is nothing scarier than the noises a house makes while it's being lifted. Once you hear these noises, I promise you that you will never want to be near a house while it's being lifted. Old houses are unpredictable and do not like new forces applied to them. You need to make sure everything is tied together. Some of these houses have their rafters joined at the ridge by a single nail, with no ridge board, and if the ledger boards are rotten, the only thing holding the roof together is the weight of the building materials. If you apply uneven force by trying to lift the rim of the house unevenly, the house will just unzip in front of you, and if you are under the house operating a manual jack, it will kill you.

What you need is not an engineer looking at span tables, but a person who specializes in old houses, or even old barns. They will have the experience to tell you how to tie the house together so that it does not collapse, will help you identify structural members that need replacing before anything is attempted, and who has seen a few houses collapse and thus has the appropriate level of respect for the operation you are about to undertake.

Last, no insurance company in this world will cover whatever happens during the lift, so I would only attempt this on a house that you own outright, and as a last resort before demolishing it. If the house collapses, you are far away at the manifold, excavator keys in your pocket, and ready to put the pieces in the dumpster.

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    @Cheery I appreciate the time you took to answer my question and the well defined wording to paint a clear picture. We've got a house lifter coming over to give us a quote soon. He didn't make it here today but fingers are crossed. His estimate to lift AND dig us a full basement was 9-14k. He's been lifting homes since the 80's. We'd consider it a blessing to get this service at that price point. Oct 18, 2023 at 0:23
  • Random hand-waving estimates in my area, a decade ago, for a lift to increase headroom in the basement, started at a bit over $30k for lifing a 1000-square-foot two-storey. That struck me as entirely reasonable; frankly, less than I expected.
    – keshlam
    Oct 18, 2023 at 14:49
  • The house lifter is coming tomorrow late morning to give us a quote. I drew up a plan for the foundation and support beams to support the original house footprint. If anyone see's an issue, please point it out for me. The number of support posts doesn't bother us, we'd just be ecstatic to have a nice sized full basement. Oct 19, 2023 at 4:44
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  1. Is your buddy on justanswer.com a licensed engineer?
    • Is he willing to sign off paperwork stating that this is what you need?
    • If he is, then he's risking his license and career on the answer he gave. If so, you can probably trust it. If not, he's just some guy on the internet (just like me).
  2. The risk of injury, damage, destruction or death is VERY high on a project like this. I'm all for DIY, and I held up my porch roof with a 6x6" beam while I reconstructed the porch underneath, but a whole house? Nope, I'm not gonna go there.

I'd really recommend that you get a professional in to do this. You've already done the majority of the work (gutting the house), so the "only" thing they have to do is get there with their equipment, do the lift, brace the structure while you're working underneath, then set it back down on the new foundation/walls.

  • They'll be experienced.
  • They'll be trained.
  • They'll have licensed engineers designing the lift schedule.
  • They'll have all the proper equipment.
  • They'll know how to build, place & brace the cribbing to ensure the house remains level and stable during the lift, construction, and lowering.
  • They'll have insurance in case something goes wrong.

BTW- if you do this on your own and the house tips over, good luck getting your insurance to cover that. And what happens if it falls onto someone else's property?

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    They'll also check for things which say you shouldn't proceed at all. Neighbor was going to have their house lifted since it was slightly off it's foundation, then their team discovered the main roof beam was cracked and unlikely to survive that operation. And replacing that beam was unlikely to survive while off the foundation, so no reputable pro would touch either. Wisest course, despite their not having wanted to even gut-rehab, was to demolish and rebuild. I think they may have been able to get away with the "we retained one wall so it isn't new construction" dodge.
    – keshlam
    Oct 17, 2023 at 13:26

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