Cambridge was formed from three historic communities, Galt, Preston and Hespeler, and that history shows in the housing. Stone and brick homes near the Grand River, older two-storeys on tree-lined streets and mid-century bungalows sit alongside newer subdivisions. Older homes have real charm, but they were built long before modern insulation, and keeping them warm in winter can feel like heating the outdoors.
Here’s how to make an older Cambridge home warmer without running your furnace into the ground.
Respect the House, Then Fix the Heat Loss
Older homes were built to breathe. They often have plaster walls, solid masonry and attics that were never designed for deep insulation. That doesn’t mean they can’t be made warmer. It means the upgrades need to be done thoughtfully, with attention to moisture and ventilation, not just maximum R-value.
The good news is that the most effective upgrade, the attic, is also usually the simplest.
1. Start at the Top
Heat rises, and in many older Cambridge homes the attic has only a few inches of old insulation, or a patchwork of different materials added over the years. Attic insulation in Cambridge brings that up to modern levels and is typically the change that most reduces how long the furnace runs.
Ontario’s attic rebate program targets R-50. With blown-in cellulose, that’s about 13 to 15 inches; with blown-in fibreglass, about 17 to 19 inches. Cellulose is denser and slows air movement well, which helps in leaky older attics.
Check for These First
- Old or contaminated insulation: Damaged, wet or pest-infested material should be cleared with attic insulation removal.
- Ventilation: Older attics may have limited soffit venting. Baffles keep airflow open once insulation is added.
- Air leaks: Gaps around chimneys, plumbing and wiring should be sealed before insulating.
- Old wiring: Very old homes may have wiring that shouldn’t be buried in insulation. A proper assessment checks for this.
2. Add Insulation to Hollow Walls
Some older frame homes have empty wall cavities. If your exterior walls feel cold, drill and fill insulation can add insulation without removing plaster. Solid masonry walls work differently, so an assessment will tell you what’s possible.
3. Seal the Basement
Fieldstone and older block foundations often let in a lot of cold air. Insulating and sealing rim joists with spray foam insulation cuts drafts at the foundation and helps keep floors warmer.
4. Everyday Ways to Hold Heat
- Use interior storm windows or window film on older single-pane windows.
- Hang thermal curtains and close them at night.
- Close the fireplace damper, or use a chimney balloon in a fireplace you never use.
- Keep radiators and registers clear of furniture.
- Have your furnace or boiler serviced annually.
For homeowners who want to understand how heat moves through older houses, Natural Resources Canada’s Keeping the Heat In guide is a thorough free resource.
Rebates for Cambridge Homes
The Home Renovation Savings attic rebate offers up to $1,250 to bring an attic from R-12 or less up to R-50, with no energy assessment required. It’s completed through participating contractors, and gas-heated homes must be Enbridge Gas customers. For older homes that need several upgrades, the assessment-based path offers more across attic, walls and foundation. The program is extended to November 30, 2026. Visit our Cambridge energy rebate page for details.
Frequently Asked Questions
Is it safe to insulate an old house?
Yes, when it’s done with proper attention to ventilation, moisture and any old wiring. That’s why an on-site assessment matters before any work.
Can stone or brick walls be insulated?
Solid masonry walls usually can’t be filled like frame walls. The attic and basement are often the better first investments in these homes.
How do I know what’s in my attic now?
A professional assessment will identify the type and depth of existing insulation and flag anything that needs to be removed.
Keep Your Cambridge Home’s Character, Lose the Drafts
Pro Insulation Contracting will assess your home and recommend upgrades that fit how it was built. Book a free assessment or call (416) 315-0471.
