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INSTANT QUOTE

3-season sunroom: Comfortable April through November in Ontario. No HVAC, no insulation in the walls. About 45–55% of the cost of a 4-season build. Best for homeowners who want extended outdoor living but don't need a true year-round addition.

4-season sunroom: Insulated walls (R-15 to R-30+), triple-pane glass, mini-split heat pump or HVAC tie-in. Counts as finished living space for MPAC assessment and resale. Returns 60–80% ROI at sale and adds genuine living square footage.

If you're staying 5+ years and want a real "second living room," go 4-season. If you want a cottage-feel extension for warmer months, 3-season delivers way more space per dollar.

Studio: Single-slope shed roof. Cheapest, modern look, easiest to attach to most homes. Best for contemporary builds and tight budgets.

Gable: Peaked roof, classic suburban look. 15–25% more than Studio. The default "sunroom shape" most buyers picture.

Hip: Four-sided roof — slopes on all sides. 25–35% more than Studio. Premium curb appeal, great for high-end neighbourhoods.

Edwardian / Victorian: Ornate peaked roof with bay-window front. 50–65% more than Studio. Best for heritage homes or premium upgrades.

Lean-To / Conservatory: Glass walls AND glass roof attached to the house wall. Often the most expensive style — true conservatory feel.

Solid insulated roof: Shingled or metal, fully insulated. Keeps the sunroom cool in summer, quiet during rain/snow, and 25–40% cheaper than glass. The standard choice for 4-season builds.

Partial glass (skylights): Best of both worlds — insulated roof with strategic glass panels for light. Adds 15–25% to solid roof cost.

Full glass roof (conservatory): Pure conservatory experience. Stunning natural light. Drawbacks: gets hot in summer (need shade or solar-control glass), louder during storms, harder to insulate. Best for 3-season builds.

Yes — every sunroom build in Ontario requires a building permit, regardless of size. 4-season sunrooms also require engineered drawings stamped by a structural engineer, plus zoning compliance review for setbacks and lot coverage.

Permit costs in the GTA typically run $500–$2,500 depending on municipality and project value. Toronto runs higher (often $1,200–$3,000+ for sunrooms). Our quote ranges include standard permit costs — engineered drawings for complex 4-season builds are extra and confirmed on-site.

Our contractors handle the entire permit process as part of the project.

4-season insulated sunrooms: Reassessed by MPAC as finished living space. Property tax increases proportionally — typically $300–$1,500/year for a mid-sized build in the GTA. The tradeoff is significant resale value gain (typically 60–80% of cost recouped).

3-season sunrooms: Generally classified as a non-living-space addition. May trigger a small reassessment but typically much less than 4-season. Some homeowners specifically choose 3-season to avoid the higher tax bracket.

MPAC reassessment usually happens 12–24 months after final building permit closure — not immediately upon build completion.

Existing concrete slab: Works for most 3-season sunrooms if the slab is in good condition, properly drained, and 4+ inches thick. Saves $5K–$15K versus pouring new.

For 4-season builds, the slab needs frost-protected footings (4-foot minimum depth in southern Ontario, 5-foot in northern). Most existing patios don't have this — they're typically built on grade. Adding insulated footings around the perimeter is common.

Wood deck: Can support 3-season screen-and-glass builds with reinforcement, but usually requires upgrade to support snow loads and structural attachment. 4-season builds on existing wood decks are rare — most builders recommend slab.

Mini-split heat pump: The standard solution for 4-season sunrooms. One unit handles both heating and cooling. Installed cost typically $4,500–$8,500 in the GTA. Energy-efficient and quiet.

Baseboard electric heat: Cheapest heating option ($800–$2,000 installed) but expensive to run on Ontario electricity rates. Better for occasional-use 4-season builds.

Tie into existing furnace/AC: Possible but usually costs 2–3x a mini-split because of ductwork extension and possible capacity upgrade. Only makes sense if your existing system has significant capacity headroom.

3-season sunrooms: Typically no permanent heating. Some homeowners add a portable heater or fireplace for shoulder months.

Timelines vary by season rating and complexity:

3-season sunroom (existing slab): 3–6 weeks from contract to completion.
3-season (new foundation): 5–8 weeks.
4-season sunroom: 8–14 weeks total — 4–6 weeks of that is permit + engineered drawing approval (longer in summer when permit queues are backed up in Toronto, Vaughan, and Mississauga).
Custom Edwardian or full conservatory: 10–18 weeks.

Best practice: start your planning in winter so the build wraps up by early summer.

A traditional home addition (insulated walls, drywall, no glass-heavy walls) typically costs $400–$650/sqft in the GTA and returns 70–80% at resale.

A 4-season sunroom is comparable on per-sqft cost ($280–$850/sqft) but has unique appeal — buyers see it as a bonus "lifestyle" room, not just more square footage. ROI typically lands in the same 60–80% range, but the room is much faster to build and gets you outdoor-living vibes a regular addition can't match.

Choose a traditional addition if you specifically need more bedrooms or a real climate-controlled office. Choose a sunroom if you want the indoor-outdoor experience and are okay with more glass.