Exterior doors are one of the most overlooked sources of heat loss in a home. Over a five-month Ottawa heating season, a damaged or poorly sealed door quietly adds up — here is how, and what to do about it.
Doors do not feel like a big energy item. They are small compared to walls and windows, and a draft seems like a minor thing. But in an Ottawa winter the math works against you: the heating season runs roughly five months, the temperature gap between inside and outside is often forty degrees or more, and an exterior door is one of the largest single openings in your wall. A door that does not seal properly leaks heat every hour of every one of those months — and you pay for all of it.
Worried about your heating bill? We seal and repair heat-leaking doors across Ottawa & the Valley. Call 613-265-3667 or request a free quote.
Understanding the difference tells you which fix you actually need.
Air leakage is the big one and the one you can feel. Warm indoor air escapes — and cold outdoor air pours in — through the gaps around the door: worn weatherstripping, a failed sweep, an unsealed threshold, and the joint where the frame meets the wall. This is usually the dominant source of a door's heat loss, and the good news is that it is almost entirely a sealing and alignment problem, not a reason to replace the door.
Conduction is heat passing straight through the material of the door itself. A thin, hollow, or old uninsulated door simply lets more heat through than a modern insulated one. You cannot feel a draft from conduction — the door surface just stays cold. This is the part that, when it matters, points toward an insulated replacement rather than a repair.
For most homes with a heat complaint, air leakage is the culprit and it is the cheap fix. That is the encouraging part of this story.
The same gap leaks far more heat here than it would in a mild climate, for three reasons. The temperature difference is huge, so air rushes through any opening faster. Wind pressure against the house forces even more air through gaps on cold, blustery days. And the heating season is long — that small leak is not a few weeks of nuisance, it is months of continuous loss. Multiply a modest hourly leak by an Ottawa winter and a "minor" draft becomes a real line on your gas or hydro bill.
The cheapest fixes usually return the most, which is rare and worth taking advantage of:
The bill is only half the reason to fix a leaking door. A sealed door means no more cold draft across the entryway, no more chilly floor by the front hall, and an even temperature through the rooms nearest the door. It also stops the condensation and frost that drafts cause at the door edge — moisture that, left alone, rots frames and feeds mould. Sealing a door is one of those rare home fixes that costs little, pays itself back through the winter, and makes the house noticeably more pleasant to live in from the first cold day.
If this article points to a problem you're dealing with right now, these pages go deeper — or you can browse the rest of the blog and request a free quote:
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