How do i add blown-in insulation to my 1940s bungalow walls in Riverview without removing the clapboard siding?

Blown-in insulation through the exterior (or interior) is absolutely doable in your Riverview bungalow without touching the clapboard — it's actually one of the most common retrofits we see on post-war NB homes. The process involves drilling small holes to inject loose-fill insulation into each stud bay, then patching the holes so they're virtually invisible. Here's what you need to know before calling a contractor.

The Two Access Approaches

Drilling from the exterior is the most common method for clapboard homes. A contractor removes a single clapboard near the top of each stud bay, drills a 2–3 inch hole into the sheathing, injects the insulation (typically dense-pack cellulose or fiberglass), then replaces the clapboard. Done well, it's nearly invisible — done poorly, you'll see every patch. Ask contractors specifically about their patching process and ask to see past work.

Drilling from the interior is the alternative if you're planning to re-drywall anyway, or if the exterior finish makes exterior access tricky. Holes are drilled through the drywall or plaster, insulation injected, then patched and painted. Plaster walls in a 1940s home can be brittle — an experienced installer will know how to minimize cracking.

Dense-pack cellulose is the preferred product for older NB homes. It fills voids completely, resists settling, and has some air-sealing properties — important because your 1940s bungalow almost certainly has no vapour barrier and significant air leakage through the wall cavities. Fiberglass loose-fill is also used but can settle over time in wall cavities if not properly dense-packed.

Your 1940s Riverview bungalow likely has 2×4 stud walls with zero insulation — just sheathing boards, an air gap, and clapboard. You're looking at roughly R-13 to R-15 after a dense-pack cellulose job, which is a meaningful improvement but still below the NBC 2020 Tier 2 targets for new construction. For a retrofit, it's still excellent value.

Cost in the Moncton/Riverview market runs roughly $3,500–$7,000 for a typical bungalow, depending on square footage, number of stories, and access complexity. Get at least three quotes — pricing varies considerably between contractors.

One thing to flag before you start: balloon framing was common in 1940s construction, meaning stud bays may run continuously from the basement to the attic without fire blocking. This creates two problems — the insulation can fall straight down into the basement wall cavity, and it's a fire safety concern. A good installer will probe each bay before drilling to confirm the cavity depth and identify any blocking. If your walls are balloon-framed, the contractor needs to address the top and bottom blocking as part of the job.

Also worth checking: knob-and-tube wiring was still present in many NB homes built in the 1940s. Blown-in insulation cannot be installed around active knob-and-tube — the wiring needs air circulation to dissipate heat, and encasing it creates a fire hazard. Have an electrician assess your wiring before booking insulation work. If K&T is present and active, you'll need to address the wiring first. A licensed electrician (licensed through NB Dept. of Justice and Public Safety — Technical Inspection Services) can assess and quote the upgrade.

NB Power's Total Home Energy Savings Program offers rebates for insulation upgrades — worth checking before you start, as the rebate can meaningfully offset your cost. Your contractor may also be familiar with the application process.

For Riverview specifically, building permits are issued through the Town of Riverview Development Services — check townofriverview.ca for current requirements. Insulation-only retrofits often don't require a permit, but if any electrical work is triggered, that absolutely does.

Browse insulation contractors in our directory at New Brunswick Construction Network — look for contractors who specifically list dense-pack or blown-in wall insulation as a service, not just attic insulation work.