How long does it take to spray foam the rim joists and basement walls in a Saint John home?

For a typical Saint John home, spray foaming the rim joists takes 2–4 hours, while the basement walls add another 1–2 days depending on size and prep work — so most complete basement spray foam projects run 1–3 days total from setup to cleanup.

The rim joists are almost always the fastest part of the job, and they deliver some of the best return on time invested of any insulation upgrade in an NB home. A standard Saint John house with a rectangular footprint has roughly 150–200 linear feet of rim joist. Applying 2 inches of closed-cell spray foam to that entire perimeter — which gives you approximately R-12 to R-14 and a complete air and vapour barrier in one pass — typically takes an experienced crew 2–4 hours once they're set up. Setup itself (heating the spray rig, mixing the chemicals to the right temperature and ratio, masking off areas you don't want foam on) adds another 30–60 minutes.

Basement walls take considerably longer because of the surface area involved. A typical Saint John home with an 800–1,000 square foot footprint and 7-foot basement walls has roughly 1,000–1,200 square feet of wall surface. At 2 inches of closed-cell foam (the minimum you want for vapour control in NB's climate), a two-person crew can cover 400–600 square feet per hour once spraying begins — but the total project time stretches out because of masking, working around mechanicals, moving equipment, and the foam's reaction time between passes if you're building up thickness. Expect a full day for the walls alone on a standard basement, or two days if the space is cluttered, has complex geometry, or requires more than 2 inches of foam.

Saint John's coastal conditions matter here. The persistent wind and high relative humidity off the Bay of Fundy make Saint John basements particularly prone to moisture infiltration through foundation walls. Closed-cell spray foam is the right call — it bonds directly to the concrete, eliminates the air gap where condensation forms, and its low permeance (roughly 1 perm at 2 inches) acts as a Class II vapour retarder. Open-cell foam is not appropriate for Saint John basement walls because it absorbs moisture and will not perform as a vapour barrier.

A few practical timing notes. Spray foam requires ambient and substrate temperatures above 15°C (ideally above 18°C) for proper adhesion and cure. In Saint John, this means basement spray foam projects are best scheduled from May through October. Winter projects are possible but require the contractor to pre-heat the basement and the spray rig chemicals, which adds time and cost. Also, the foam needs 24 hours to fully cure before you cover it — NB Building Code requires spray foam to be covered by a thermal barrier (typically ½-inch drywall) because uncovered spray foam is a fire hazard. Factor that into your project timeline if you're planning to finish the basement.

Total project timeline summary: Rim joists only — half a day. Rim joists plus basement walls — 1 to 3 days for spray application, plus 24 hours cure time, plus whatever time you need for the thermal barrier installation afterward.

For a Saint John basement, budget roughly $3,000–$7,000 for closed-cell spray foam on the walls and rim joists combined, depending on basement size and foam thickness. This project is also eligible for NB Power's Total Home Energy Savings Program rebates — but you'll need a pre-retrofit EnerGuide evaluation completed before any work begins to qualify.

If you'd like help finding a spray foam contractor in the Saint John area, New Brunswick Insulation can match you with local professionals at no cost. You can also browse insulation contractors through the New Brunswick Construction Network directory at newbrunswickconstructionnetwork.com/directory?category=insulation.