Blown-In Cellulose Attic Top-Ups for Airdrie Homes

The Problem It Solves

Plenty of Airdrie attics were insulated to whatever the builder was required to install at the time, and that number was lower than today’s target. Add twenty or thirty years of settling, a few trips across the joists by the cable installer, and a hatch nobody ever put back properly, and the real coverage is thinner and patchier than the original paperwork suggests. You feel it as upstairs bedrooms that run cooler than the main floor, a furnace that cycles hard through January, and ceilings that stay cold to the touch around the outside walls.

The attic is usually the cheapest place in a house to add thermal resistance, because the space is open and nothing has to be torn out. But a thin attic is rarely just a thin attic. Warm air leaking up through light fixtures, plumbing stacks and top plates carries heat and moisture straight past the insulation, and fibre blown over those leaks simply hides them. In our climate that moisture turns into frost on the underside of the roof sheathing, which is a separate problem with its own page on this site.

The other common story is uneven depth. Loose fill piles up under the hatch where it was easy to reach and thins out toward the eaves, where the roof slope pinches the space down. The eaves sit above the exterior walls, which is exactly where the ceiling needs the most help. A top-up done by eye from the hatch tends to repeat that pattern instead of fixing it, which is why we measure across the whole attic before quoting depth.

How It Works

A cellulose top-up adds a continuous blanket over what is already there. The installer pulls the hose to the far corners first and works back toward the hatch, filling low spots and the eave area before building overall depth. Because cellulose is a dense, fine fibre, a deep layer resists air moving through it better than lighter loose fill, which helps on windy days when cold air pushes in at the soffits. Depth rulers stapled to trusses across the attic give you and any inspector a visible check on what was installed.

We blow to the settled depth for the R-value you are after, plus the settling allowance printed on the bag chart, and we count bags against the chart’s coverage figure for the attic area. That count matters more than eyeballing depth, because cellulose blown too light looks thick on the day and loses R-value as it settles. Before any of that, we check that soffit baffles are in place and that the obvious air leaks at the ceiling plane have been dealt with, because a thick layer of fibre makes both of those jobs far harder later.

What Decides the Specification

The target depth comes from the product, not from a rule of thumb. Different cellulose products have different densities and coverage charts, so the inches needed for about R-60 shift a little between them. We also account for what is already there: old, compressed fibreglass still counts, but not at its original label value. If the house has a heat-recovery ventilator, the Section 9.36 benchmark drops to about R-49, which some owners choose as their target instead.

The attic itself sets limits. Low-slope roofs leave very little room at the eaves, and there the rafter vent and the settled depth have to share the space. Ceiling drywall and framing spacing matter too: cellulose is heavier than loose fibreglass, so on ceilings with wide framing spacing or thin, already-sagging board, we look hard at whether fibreglass is the better fill. Attic access matters as well. A tiny hatch in a closet can still work, but it changes how the hose is run and how carefully the room below is protected.

Around Airdrie

Cellulose top-ups make the most sense in Airdrie’s older established areas, where attics have had decades to settle. In Hillcrest and Big Springs, many homes from the 1970s through the 1990s still carry their original attic fill, often a thin layer of fibreglass or old cellulose that has packed down unevenly and been disturbed around the hatch. Those attics are usually roomy enough to take a deep new layer. The same pattern turns up in older homes in Crossfield. Where we find rodent droppings or damaged fill, we recommend removal first rather than burying the problem.