When insulating a custom home in Ontario, the debate between spray foam and batt insulation comes up on almost every project. Both work. They perform differently, cost differently, and suit different situations. At LR Contracting we install both — here is an honest breakdown of what actually performs in Halton Region's climate.
Closed-cell spray foam applied to exterior walls and roofline on a custom home renovation in Oakville — this is the same project before drywall.
What is Spray Foam Insulation?
Spray foam is a two-component chemical mixture that expands on contact, filling every gap, crack and cavity. It comes in two types:
- Open-cell spray foam — softer, more flexible, lower R-value per inch (R-3.5 to R-4). Good for interior sound dampening and areas where vapour transmission is acceptable.
- Closed-cell spray foam — rigid, R-6 to R-7 per inch, acts as its own vapour barrier, adds structural rigidity. This is what we use on exterior walls and rooflines on custom homes in Oakville.
What is Batt Insulation?
Batt insulation is pre-cut fibreglass or mineral wool sized to fit between standard stud bays. Fibreglass achieves roughly R-3.5 per inch; mineral wool achieves R-4 per inch. It is significantly cheaper per square foot than spray foam and faster to install in large open wall cavities.
Side-by-Side Comparison
🟡 Closed-Cell Spray Foam
- R-6 to R-7 per inch
- Air-tight seal — no gaps around wires or pipes
- Acts as vapour barrier — no poly required
- Adds structural rigidity to walls
- Ideal for attics, crawl spaces, rim joists
- Cost: $3–$5 per sq ft installed
- Does not settle or compress over decades
⬜ Batt Insulation
- R-3.5 to R-4 per inch
- Gaps possible around wires and pipes
- Separate vapour barrier (poly) required
- Lower cost: $0.80–$1.60 per sq ft installed
- Good for large flat interior walls
- Can compress or settle over time
- Easy to remove and re-access later
Closed-cell spray foam on all exterior walls, rooflines and rim joists — then mineral wool batt on interior partition walls for sound control. Best thermal performance where it matters, at a manageable total cost.
When We Recommend Spray Foam
- Attics and sloped rooflines — fills every void, no air leakage under sheathing
- Rim joists and band joists — major heat loss points in most Ontario homes
- Crawl spaces — seals and insulates in one step
- Sunrooms and additions — spray foam on all surfaces creates a superior thermal envelope before drywall
- High-performance custom homes — when energy performance is a design goal
When Batt Makes More Sense
- Interior partition walls — mineral wool sound batts for room-to-room isolation
- Large flat exterior wall cavities in standard construction — performs well at much lower cost
- Budget-sensitive projects — batt gets the job done at a fraction of spray foam cost
- Areas requiring future access — batt can be removed, spray foam cannot
Typical Costs for a Custom Home in Oakville
- Full spray foam approach (4,000 sq ft home): $28,000 – $45,000
- Full batt approach: $8,000 – $14,000
- Hybrid (spray foam exterior + batt interior): $18,000 – $28,000
Get a Free Insulation Quote
We install spray foam, batt and blown-in across Oakville and Halton Region.
At LR Contracting, we assess each wall and ceiling assembly and recommend exactly what makes sense — without upselling spray foam where batt will perform perfectly well.