Three season sunrooms in Rossmoor, CA - a bright room planned for how you'll use it

A three season room in the Orange County area usually costs about $110 to $160 per square foot, labor included. That figure covers builder-grade windows, siding, roofing and standard electrical work, but not insulation, heating and cooling, plumbing or construction permits, so ask which of those each quote includes. The size, the base and the roof move it most, and the estimate gives you your own number.

Often not by as much as people expect. One Canadian sunroom company points out that both kinds of room share the same plans, engineering approvals, permits and foundation costs, so the gap can be smaller than you'd think. That's why our estimate shows both prices.

Decide whether you'll ever want heat or air conditioning in the room, and settle it before design starts, because that choice changes how the room is built. An all-year room is heated or cooled, opens to the house and counts as living space, and its windows have to meet tighter limits on air leaks, water leaks and heat loss. A three season room stays closed off, and one sunroom maker puts an outside-grade door between it and the house so your home stays insulated when the room gets very hot or cold.

Plan how the room ties into a base that can carry it. Sunroom building standards call for a continuous load path, framing that carries the room's forces down to the foundation, and that includes rooms on slabs and decks, so I check what's under yours first. One Canadian sunroom maker notes that a wood deck base adapts easily and may cost less, concrete is the strongest and permanent, and pier and beam, posts holding up beams, suits slopes and existing surfaces.

It likely will darken the part of the house the room joins, according to one Canadian sunroom company, even though a solid roof gives good summer shade. That trade-off matters most when the room sits off a kitchen or family room where you count on daylight, so it's one of the first things we go over.

Check before you build, because the county's list of work that typically needs a permit names building additions, patios and decks, along with electrical, heating and cooling, and plumbing work, even though it doesn't name three season rooms. OC Development Services issues building permits in unincorporated Orange County, and any wiring or heat you plan for the room falls under that same list. We check which office covers your address, and when the work needs a permit, we take care of the application and meet the inspector.