Cost lever Sold under many names
4-season sunroom
A fully insulated, climate-controlled sunroom built to addition-level standards — insulated glass, insulated walls/roof/floor, tied to heating and cooling — usable year-round.
What it means for you
The closest of the glass rooms to a true addition, and the only one that generally counts as heated living space in an appraisal (on a real foundation, on the home's HVAC, to code). That's also why it costs much more: the real foundation, thermally broken framing, and insulated glass package are code-driven, not upsell trim.
Where you'll see it
The premium tier on a sunroom quote.
Also sold as: 4-season room · four-season room
Defined by Makani Haoa
Verified against NC Energy Code (NCECC R402.3.5)
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