Sunroom Calculator
Calculate the complete cost of a sunroom or four-season room addition. Compare screened porch, 3-season, 4-season, and solarium options — with glass performance, foundation, HVAC impact, and ROI analysis.
Cost and ROI comparison for all sunroom types at your 200 sqft size in moderate climate.
| Type | Cost Est. | Usable Months | Value Added | ROI |
|---|---|---|---|---|
| 3-Season Screened Porch | $10,000 | 6 months | $5,000 | 50% |
| 3-Season Enclosed | $22,500 | 8 months | $10,800 | 48% |
| 4-Season Insulated | $42,500 | 12 months | $22,100 | 52% |
| Solarium / Greenhouse | $50,000 | 12 months | $22,500 | 45% |
Operating cost impact of adding an HVAC-conditioned sunroom to your home.
Usable ~6–8 months/year (climate dependent)
No installation cost
Only option for screened porches
Year-round use
Most efficient option — COP 3–4
No ductwork needed, quick install
Year-round use
Requires HVAC capacity assessment
May need system upgrade if oversized
Sunroom vs. Enclosed Porch vs. Four-Season Room: Understanding the Difference
These terms are often used interchangeably but represent meaningfully different products with very different costs, performance, and resale value.
The Four Sunroom Types
Screened porch ($5,000–$15,000): Open screens, no glass, no HVAC. Usable from spring through fall in most climates — essentially year-round in Florida and Texas. Cannot be used in rain, wind, or cold. Most affordable entry point.
3-season enclosed ($15,000–$30,000): Glass panels, no significant insulation, no HVAC. Comfortable when outside temps are above 40–50°F. Popular in the Mid-Atlantic and Midwest for 7–8 months of use. Lower cost but limited winter utility in cold climates.
4-season insulated ($25,000–$60,000): Full insulation, double or triple low-E glass, dedicated HVAC (usually a mini-split). Year-round use. Qualifies as conditioned living space in most appraisals — the best financial choice for adding square footage.
Solarium ($30,000–$70,000): Architectural glass ceiling and walls, maximum natural light. A premium product for maximum natural light, plant cultivation, or aesthetic impact. Requires the most careful glass selection and HVAC sizing.
Sunroom Cost Formula
Glass Area ≈ Floor Sqft × 1.5 (walls + ceiling combined)
Glass Cost = Glass Sqft × Cost Per Sqft ($15–$40 depending on type)
Annual Operating Cost = Monthly HVAC × 12
Value Added = Total Cost × ROI% (40–55% depending on type)
Example: 200 sqft 4-Season Sunroom, South-Facing
200 sqft | 4-Season Insulated | Double Low-E Glass | Concrete Slab | Mini-Split
| Sunroom structure (walls, roof, framing) | $22,000 |
| Double low-E glass (300 sqft × $25) | $7,500 |
| Concrete slab foundation | $7,000 |
| Mini-split HVAC installation | $4,000 |
| Electrical (outlets, lighting) | $1,500 |
| Interior finishing | $3,000 |
| Permits and inspections | $800 |
| Total Project Cost | $45,800 |
| Estimated value added (52% ROI) | $23,800 |
| Monthly HVAC operating cost | +$100/mo |
| Usable months per year | 12 months |
At $229/sqft all-in, this is significantly cheaper than a conventional addition ($200–$300/sqft) for comparable square footage — and provides a more distinct, light-filled space that traditional additions don't replicate.