The house next door sold last spring. By August it was gone, and now there’s a hole where it used to be, deep enough for a basement and a fourplex on top. The excavator starts at 7 a.m. Your coffee cup rattles on the counter.
Then one morning the bathroom door won’t close properly. You look at the drywall above it, and there’s a crack you’re pretty sure wasn’t there last month.
If that sounds familiar, you’re not being paranoid. Foundation damage from neighbour construction does happen, and with more infill building across Metro Vancouver, more homeowners are living next to a deep dig. There’s a clear sequence to follow, whether the work hasn’t started yet or you think the damage is already done.
Did Construction Next Door Damage Your Foundation?
Foundation damage from neighbour construction happens when work on an adjacent lot moves the soil your home sits on, and your house doesn’t have to touch the site for that to happen. Most cases come down to four causes.
- Loss of side support. When a neighbouring lot is excavated for a deeper basement, the soil that supports your foundation from the side can be removed, and footings near the property line can shift toward the excavation before shoring is fully in place.
- Dewatering. Builders often pump groundwater out of an excavation to keep it dry. That can lower the water table under nearby homes too.
- Vibration. Demolition, soil compaction and some pile installation methods send vibration through the ground. Loose or sandy soils can settle as a result.
- Changed drainage. New grades, retaining walls and hard surfaces can send runoff toward your side of the property line.
Soil type decides how much any of this matters. On Richmond and Delta sites with a high water table, pumping groundwater out of a neighbouring excavation can lower the water level under nearby homes, and peat soil compresses as it dries out. That’s one reason homeowners in Richmond and Delta should pay close attention when a big dig starts nearby.
Slopes add another layer. On the North Shore, a home uphill from an excavation can lose support in a way that a flat Surrey lot wouldn’t. If you live on a hillside in North Vancouver, the direction of the slope matters as much as the distance to the hole.
Why Foundation Damage From Neighbour Construction Is More Common in 2026
The short answer is more building on smaller lots, closer to existing homes.
BC’s small-scale multi-unit housing rules (Bill 44, passed in 2023) require municipalities with more than 5,000 people to allow three to four units on most single-family and duplex lots, and up to six on larger lots near frequent transit. Add laneway homes and deeper basements, and a lot of older houses now have an excavation within a few metres of their foundation.
That doesn’t mean builders are careless. Deep excavations need permits, and many municipalities require engineered shoring and professional supervision. But older homes in established neighbourhoods were never designed with a deep hole next door in mind. Tight urban lots in Burnaby and East Vancouver leave very little room between the dig and the neighbour’s footing.
(If the construction is your own renovation rather than the neighbour’s, that’s a different situation. We cover it in our guide to finding foundation problems during a renovation.)
What to Do Before the Excavator Shows Up
The most useful thing a homeowner can do before construction starts next door is create a dated record of their home’s current condition, because any conversation with a builder or insurer later depends on showing what changed.
Here’s a simple checklist. It takes an afternoon.
- Walk through the house and take dated photos and video of every room, inside and out. Get close-ups of any existing cracks.
- Mark the ends of existing cracks with a pencil line and the date. If a crack grows, you’ll see it.
- Check that doors and windows open and close properly, and note any that already stick.
- Photograph the foundation walls, the basement or crawl space, and the side of the house facing the lot.
- Ask the builder or site supervisor for the geotechnical engineer’s name and contact information.
- Ask whether a pre-construction survey of your home is planned, and whether you can get a copy.
That last point matters. In Vancouver, when a house excavation needs geotechnical design (peat, liquefiable soils, basements deeper than eight feet, or sites next to earlier excavations), the City’s Building Bulletin 2016-005 expects the professional to survey adjacent properties before work and to follow up where movement may occur. The District of North Vancouver requires sealed shoring design for vertical cuts over four feet and a survey of structures within five feet of the property line. Rules vary by municipality, so ask your local building department what applies to the permit next door.
A builder’s survey is useful, but it’s their document. Some homeowners also book an independent foundation assessment before work begins, so they have their own baseline. You can book one by calling 604-446-9967.
Warning Signs Once Work Has Started
Once digging begins, check the house every week or so. Not every crack means trouble. Some settling is normal in any home, and our guide on when house settling is normal explains the difference. The question is whether something changed after the work started.
Use this three-level check.
Relax – Hairline cracks you photographed before the work started, and they haven’t grown – Minor nail pops in drywall with no other changes
Monitor – A crack that has grown past your pencil mark – A door that has started to rub but still closes – New hairline cracks in drywall, especially near door and window corners
Call Now – A door or window that suddenly sticks or won’t latch – New or widening cracks in the foundation wall, especially stepped or horizontal ones – Gaps opening between walls and ceilings or between trim and the wall – Floors that feel noticeably out of level on the side facing the construction – Water in the basement where there wasn’t any before
Timing is the clue. If a crack shows up two weeks after excavation begins, on the wall closest to the site, write that down. Patterns like that are what an assessment looks for.
What to Do If You Suspect Foundation Damage From Neighbouring Construction
Move quickly, but in order. Here’s the sequence.
- Document it. Photograph the damage with a date, compare it to your before photos, and note what work was happening next door that week.
- Tell the builder in writing. Email the site supervisor or builder, describe what you’ve seen, and attach photos. Keep it factual.
- Call the municipality if it looks unsafe. If the excavation looks unstable or shoring seems to be missing, contact your local building department. Excavations that don’t follow the approved shoring design can be stopped.
- Get an independent assessment. A professional assessment tells you what has moved, how much, and whether it’s likely to keep moving.
- Contact your home insurer. Ask how they handle damage from adjacent construction. Coverage varies a lot between policies.
- Get legal advice if the builder doesn’t respond. Responsibility for adjacent construction damage is a legal question. We aren’t lawyers, and this article isn’t legal advice.
Keep the paperwork calm and factual. You may be living beside this project for a year or more.
How Foundation Damage From Neighbour Construction Gets Repaired
Once the cause is understood, repairing foundation damage from neighbour construction looks much like any other settlement repair. The difference is timing.
If soil under part of your home has moved, the usual fix is to support that section on steel piles that reach stable soil below the disturbed layer. Ossum uses Ram Jack® push piers and helical piles. Which one gets used is an engineering decision, not a homeowner choice. The engineer looks at the weight of the structure, the soil and site access. Heavier homes often suit push piers, which use the weight of the house to drive the pile. Lighter structures often suit helical piles.
Your engineer may also recommend waiting until the neighbouring excavation is backfilled or the new foundation is poured, so the soil has stopped moving before the repair is designed. That can feel frustrating when your door won’t close. But a repair designed while the ground is still shifting may need to be revisited.
For many repairs involving structural support, an engineer and a building permit are part of the process. Our article on when foundation repairs need an engineer in BC walks through how that works.
You noticed something changed, you wrote it down, and you asked the right questions. That’s the hard part. The next step is to find out exactly what moved. Contact Ossum or call 604-446-9967 to book an assessment.
Sources: Province of BC, Small-Scale Multi-Unit Housing: https://www2.gov.bc.ca/gov/content/housing-tenancy/local-governments-and-housing/housing-initiatives/smale-scale-multi-unit-housing
City of Vancouver Building Bulletin 2016-005, Geotechnical and Shoring Design for 1 and 2 Family Homes: https://vancouver.ca/files/cov/2016-005-geotechnical-and-shoring-design-1-2-family-homes.pdf
District of North Vancouver Excavation Bulletin: https://docs.dnv.org/documents/excavation-bulletin.pdf
