How do you replace a foundation in an old house?

Most old houses do not need a full foundation replacement. They need repair. We stabilize the old foundation in place with crack injection, carbon-fiber straps, a power brace, helical or push piers, lally columns, or new sill and beam wood. A true full wall rebuild is rare, and we price that after we see it. We are 603 Basement Solutions, and we serve New Hampshire, Maine, and Massachusetts.

Here is what usually happens. A homeowner sees a cracked or bowing wall and assumes the whole thing has to come out. It almost never does. Tearing out a foundation under a standing house is a major job. It means temporary shoring, excavation, and risk to the structure above. Most of the time the smarter, cheaper fix is to address the part that is actually failing.

So we start with the problem, not the panic.

A thin vertical crack is often just concrete shrinking as it cured. We seal those with epoxy or polyurethane crack injection so water stops coming through. That fix carries a 10-year warranty, and it runs $1,000 to $3,000. You do not need piers for a simple crack. You need it sealed.

New Hampshire frost heave pushes soil against a wall every winter, and over years that wall can bow inward. Carbon-fiber straps hold a wall that has moved a little. That is $850 each, with a 25-year warranty on the stabilization. If the wall has moved more, a power brace gives you adjustable steel support at $1,300 per brace. We tell you which one your wall actually needs after we look. Sometimes the answer is the lighter fix.

When a footing drops because the dirt under it gave way, the wall above goes with it. That is what helical and push piers are for. We drive steel piers down to soil or bedrock that can carry the load, then transfer the house weight onto them. We self-perform our helical installs in-house, and they carry a 25-year engineered warranty. Piers run $2,700 per pier for the first three, then $2,200 per pier after that.

In an old New England house, the failure is often the wood, not the concrete. A rotted sill or a tired beam lets the floor above sag. We replace the sill and beam at $7,000 to $40,000, add lally columns or floor support posts at $1,300 to $2,500 with a 10-year warranty, and the floor comes back level. If a wall section needs backup, an auxiliary wall (a sister wall built inside the old one) runs about $1,350 per linear foot.

What drives the cost is how far the problem has gone and how much load has to move. A single crack is one number. A settling corner that needs piers and new wood is several fixes stacked together. We give you a free inspection and a free estimate, and the quote comes within 24 hours so you are not guessing.

One thing we will not do is sell you exterior excavation waterproofing. We have seen those dig-out jobs fail in about two to three years. The dirt against an old foundation is disturbed backfill, the looser fill that went back in when the house was built. It drains slowly and holds water against the wall. Digging it up and re-coating the outside does not fix that for long. Interior drainage does, and it lasts. If your real issue is a wet basement and not a structural one, that is a different fix. See our basement waterproofing page.

For the structural side, start at our structural and foundation repair hub, or go straight to foundation repair, helical piers, sill replacement, or supplemental support. Every fix above is covered by the 603 guarantee.

Want the building science behind why old foundations move? The U.S. Department of Energy’s Building America program (basc.pnnl.gov) covers foundation moisture and soil drainage. For how foundation work is treated by your policy, the Insurance Information Institute (iii.org) is a neutral starting point.

If you have an old house and a wall that worries you, call us. We will tell you what it really needs, even if that is less than you feared.

Call 603-610-1770 at tel:6036101770 or book your free inspection. Free inspection, free estimate, quote in 24 hours.

Related questions

Do I have to replace my whole foundation if a wall is cracked? Almost never. A cracked wall usually gets crack injection at $1,000 to $3,000 or carbon-fiber straps at $850 each. We replace a whole wall only when it is failing past repair, and we price that after we see it.

Can you fix a foundation without tearing the house down or digging it out? Yes. Helical piers, power braces, carbon-fiber straps, and new sill and beam wood all go in from inside or alongside the house. We do not dig out and re-coat the outside, because those jobs fail in about two to three years.

Why does my old house foundation keep getting wet? The soil against it is disturbed backfill that drains slowly and holds water, and New Hampshire frost adds pressure. The lasting fix is interior drainage, not exterior digging. See basement waterproofing.

Who looks at my foundation and how much does the visit cost? Our crew does. The inspection is free, the estimate is free, and you get the quote within 24 hours.