The True Cost of Poor Insulation

Four costs, and only one of them is on a bill

Ask a homeowner what poor insulation costs and they will tell you about heating. It is the visible cost, and in an older Ontario house with four inches in the attic it is real money every winter. But it is the smallest of the four.

1. The equipment you replace early

A furnace sized for a leaky house runs longer cycles, more often, for more months of the year. A furnace is a machine with a duty cycle, and running it harder for fifteen years instead of easier for twenty-two is a four-figure cost that never appears as a line item. The same is true of an air conditioner in a house whose attic reaches 60 °C in July.

2. The rooms you stop using

Almost every house we work in has one. The bedroom over the garage, the room above the porch, the finished basement nobody sits in between December and March. That is floor area you are heating, insuring, and paying a mortgage on, and not using. Nobody puts a dollar figure on it, but if you bought the house by the square foot you already did.

3. The building itself

This is the expensive one and it is entirely invisible until it is not. Warm moist household air leaking into a cold attic that cannot breathe condenses on the underside of the roof deck. In a Toronto January it condenses as frost; in March it melts. Do that for ten winters and you are replacing sheathing, not insulation. We have opened attics where the plywood came apart in the hand.

4. The winter you spend uncomfortable

Not a cost you can invoice, and the one people actually act on. A house that is 21 °C at the thermostat and 17 °C at the far end of the hallway is not a house you enjoy in February.

What the numbers actually look like

We do not publish a percentage saving, and you should be suspicious of contractors who do. What you save depends on your fuel, your thermostat, the rest of your envelope and the weather. Anyone quoting you "up to 40%" without having measured your house is reading it off a brochure.

What can be said with confidence: an attic at R–12 taken to R–50, with the ceiling sealed properly, is the single highest-return envelope measure available on an older Ontario house, and it is the only one the current rebate programme lets you claim on its own.

And the cost of doing it

Right now, less than usual. The attic stream of the Home Renovation Savings programme pays up to $1,250 with no energy assessment, capped at half the invoice. The figures, with sources, are here.