Waterproofing older Somerville basements

Raritan Valley Waterproofing seals cracks and stops leaks in Somerville basements, many of them under houses that are close to a century old.

Among the towns we cover, only Manville and Bound Brook have a larger share of pre-1960 houses than the county seat.

Local record

Housing units: 6,131 (ACS 2024) ¹
Built before 1960: 49.8%, about 3,053 homes ¹
Owner-occupied: 43.0% of homes ¹
Floyd rainfall: 13.34 inches measured at Somerville ²
Ida downtown: 3 to 4 feet of water in the Summer Ville ice cream shop ³

Half the houses predate 1960

Somerville has 6,131 homes, and 49.8% of them were built in 1959 or earlier, roughly 3,053. Three in four, 76.1%, predate 1980. Only 39.3% are single-family detached and 43.0% are owner-occupied (ACS 2024), so a lot of the stock is older multi-unit buildings and converted houses.

Walls from that era are often stone, brick or early block, laid with mortar that softens over decades of wet seasons. Water usually arrives through a joint or a crack long before anything floods.

Rain more than river

The Raritan forms the borough's southern edge, and Peters Brook, one of its tributaries, runs through town (Wikipedia). The worst water Somerville has recorded came from the sky: Floyd dropped 13.34 inches of rain there in September 1999 (NWS Floyd report). In Ida, 3 to 4 feet of water filled the Summer Ville ice cream shop (NJ DCA), and the borough is on the county's list of towns with Ida-affected repetitive-loss properties (Patch).

When the ground takes that much rain in two days, it pushes on every basement wall at once, uphill streets included.

Where to start in an old Somerville basement

Most of the work we expect here is narrow: inject a leaking crack in a poured wall, seal a pipe opening, repoint a weeping section of block or stone from the inside. A crack that is wider at one end, a wall that bows, or a step crack that keeps growing is movement, and that goes to a structural engineer first. We do not do structural repair, and we will tell you when a crack is past what sealing can fix.

If water comes in along several walls after heavy rain, sealing spots one at a time stops paying off, and a drain channel with a sump is worth pricing alongside it.

Somerville basement services

Other towns are listed on the service area page.