Why window performance matters as much as wall insulation, and what in-floor heating adds to a Muskoka home.
Why windows are the weak point in almost any home's envelope
Even a wall built to a high R-value has one component that performs far worse by comparison: glass. A window loses far more heat per square foot than an insulated wall does. That matters more on a Muskoka home with large windows oriented toward a view or the water, since more glass means more surface area for that heat loss to happen through.
The building code recognizes this directly. Under SB-12, once glass and doors exceed 17 per cent of the wall area, the maximum allowable U-value for the windows tightens. Above 22 per cent, the prescriptive path is off the table entirely and the whole house has to be energy modelled.
Put plainly: the more glass a design carries, the harder each window has to work, and past a point the house has to prove itself rather than simply comply. It is a design constraint worth knowing about before you fall in love with a wall of glass facing the lake.
What Fuller installs as standard
Low-E argon vinyl windows, black exterior and white interior, on our custom homes and on the Deerhurst Townhomes.
Two things are doing most of the work in a sealed unit like that. The Low-E coating reflects heat back into the room rather than letting it radiate out through the glass. The argon fill in the cavity between the panes slows heat moving across it better than plain air does. Together they are the difference between a modern window and the single or basic double glazing still sitting in a lot of older Muskoka cottages.
In-floor heating, and where it actually sits
Every Fuller home has in-floor hydronics run in the basement slab as standard, alongside a three piece bathroom rough-in and receptacles to code, so the space can be finished later without opening the slab back up.
Radiant floor heat warms a room from the ground up rather than blowing heated air, which tends to feel more even and comfortable underfoot. It pairs particularly well with a poured slab over an ICF foundation, since the concrete's thermal mass holds and releases that heat gradually rather than cycling on and off the way a forced-air system does.
In-floor heating on the main floor is possible as an upgrade. It is a significant one, both in cost and in how it changes the mechanical design of the house, so it is a conversation to have early in design rather than a box to tick late.
How it all works together
None of these choices work in isolation. A Fox Blocks ICF foundation, R22 walls, blown-in attic insulation, spray foam at the rim joist, careful air sealing at every penetration, Low-E argon glazing and in-floor heat in the basement slab are all decisions about the same underlying question: how much heat a home loses, and how evenly it holds the heat it has.
For a buyer weighing a Muskoka build, that whole-system view is a more useful frame than any single spec in isolation.
Part three of three. Start with what R-value measures, or how ICF construction works.