How serious is a 2.5 inch drop over the length of my house’s foundation?

A 2.5 inch drop across the full length of your foundation is worth a real look, but it is not automatic panic. What matters more than the number is whether the drop is still moving. A house can settle a little and then stop, and that kind of slope is usually cosmetic. A house that keeps sinking is the one you fix. So the first question we ask is simple. Is it active?

Here is how we read it in the field.

A long, gentle slope spread over 30 or 40 feet is different from 2.5 inches of drop packed into one corner or one short wall. Spread out, that slope is gradual and often old movement that already finished. Concentrated in one spot, it points at one area giving way, and that is the kind we watch closely. Same total number. Very different story.

Look for the signs that go with it. Doors that stick or swing open on their own. Windows that bind. Cracks in drywall above doorframes, running on a diagonal. Gaps where the trim meets the floor. A floor you can feel tilt when you set a marble down. One or two small cracks alone is normal in New England. A drop plus several of those signs together is when you want eyes on it.

Why does a foundation drop in the first place? Around here it usually comes back to the soil. When your house was built, the crew dug out for the foundation and then put that dirt back around it. That backfill is looser than the ground that was never touched. It drains slowly and it holds water. Wet, loose soil compresses under the weight of the house over the years, and one part can settle faster than another. NH frost heave adds to it, freezing and pushing on the foundation through the cold months. None of that means your house is failing. It means the ground moved, and we figure out how much and whether it is done.

What we do is measure. We bring a level and check elevations across the floor and the foundation so we know the real drop, not a guess. We look at the cracks, the doors, the soil and grading outside, and the drainage. Then we tell you where it sits. Sometimes the answer is that the movement looks old and stable and you do not need structural work yet. We will say that. You do not need piers on a house that settled once and stopped.

When it is active, the fix depends on what is moving. If a footing has sunk and keeps sinking, helical piers drive down to stable soil or bedrock and carry the load there, then lift or hold the foundation level. Those carry a 25-year engineered warranty, and we install them ourselves. Helical piers run $2,700 per pier for the first three, then $2,200 per pier after that. If a beam or post inside has dropped and the floor sags, floor support with new lally columns levels it from below. Lally column work runs $1,300 to $2,500. If a wall is bowing inward from soil pressure rather than dropping, that is a different repair. Carbon-fiber straps. Those run $850 each. We match the fix to the cause. We do not sell you the biggest one on the menu.

A few things drive cost. How many piers or posts the engineering calls for. How deep we have to go to hit good soil. Access under the house. Whether we are holding the foundation in place or lifting it back toward level. We give you the number after we measure, not before.

One more thing. If water is part of why the soil moved, drying out the basement protects the repair. Our Forever Dry System pulls water off the floor wall joint with full-perimeter interior drainage so the backfill is not staying soaked. Not every settling job needs it. We will tell you if yours does.

The Insurance Information Institute notes that most standard homeowners policies exclude earth movement and settling, so do not count on insurance to cover this. Worth knowing before you call your carrier.

Want to know how serious yours really is? Call us at 603-610-1770 or book your free inspection. We will measure it, show you the numbers, and tell you plainly whether it needs work or not. Free inspection, free estimate, quote within 24 hours. Every structural repair we do is backed by the 603 guarantee.

Related questions

Is a sloping floor always a foundation problem? No. Floors slope for a few reasons, including a dropped beam or post under the house, not just the outside foundation. We level the floor and check both. A sagging floor from a tired beam is fixed with floor support and lally columns, which run $1,300 to $2,500.

How much does it cost to fix a sinking foundation? It depends on the cause and how deep we go to reach stable soil. Helical piers run $2,700 per pier for the first three, then $2,200 per pier after that and floor support runs $1,300 to $2,500. For bigger jobs like a full foundation-wall rebuild, we price that after we see it.

Will my foundation keep sinking? Maybe, maybe not. Some houses settle once and stop, and those need no structural work. Others keep moving and need piers. The way to know is to measure now and, if there is doubt, check again later to see if the number changed.

Do you do exterior excavation to fix this? No. In our experience digging the outside drainage fails again in a couple of years. We fix water from the inside with interior drainage instead, which holds up. See basement waterproofing.