Sunroom addition: what to know

What the job involves, what changes the price, and what to ask a pro.

What sunroom addition is

A sunroom addition is a glass-walled room attached to the house, built on its own foundation with framing, insulated glazing and a roof. People need one for a bright space that connects to the yard, and they must decide early whether it will be used in three seasons or year round.

Signs you need it

  • The back porch or deck has no weather protection and you want a room you can use in more months of the year
  • The house has few windows on one side, and you want more light and a view of the yard
  • The existing porch roof leaks or sags and needs to be replaced with a more permanent structure
  • You want a room that can be heated and cooled, not an open porch with screens
  • The space has to connect to the house through a doorway or wall that will need opening

What the pro does

  • Check the setback, the drainage and the foundation options, and decide whether the room needs a slab or a footing
  • Build the foundation and the floor framing, and waterproof the joint where the room meets the house
  • Frame the walls and the roof, with the header and connection to the existing structure built to the plan
  • Install the glazing, the doors and the roof panels, with flashing at every joint and a drainage path
  • Run electrical, and if the room is year round, install heating and cooling with the ducts and the thermostat
  • Finish the interior with flooring, trim and paint, then check the seals and the ventilation before use

What changes the price

Every job is different, so we do not publish prices. These are the things that move the quote up or down.

  • Three-season or year-round use, which changes the insulation, the glazing and the heating and cooling
  • Glazing type and size, such as double or triple-pane units, tinted or low-emissivity coatings and the frame material
  • Roof type, whether it is glass, polycarbonate, solid roofing or a combination
  • Foundation requirements, which depend on the soil, the frost depth and the slope
  • Connection to the house, including the door, the wall opening and any header work
  • Electrical, heating and cooling scope, and the number of outlets, lights and fans

What a written quote should spell out

  • Glazing specifications, including the frame material, the glass type and the seal warranty
  • Roof system named by material and the flashing and drainage details
  • Foundation type and the floor finish, with the connection to the house described
  • Insulation and air seal method, and whether the room is rated for year-round use
  • Heating, cooling and electrical scope, with the permit and inspection steps

Questions to ask before you hire

  • Will this be a three-season room or a year-round room, and how does that change the build?
  • What glass do you use, and what is the warranty on the seals?
  • How is the roof sealed where it meets the house, and how is water drained away?
  • What foundation will you build, and how is it tied to the house?
  • How is the room heated and cooled, and is the system sized for the glass area?
  • Can you show me a sunroom you built with a similar roof and glazing?

Red flags

  • The pro does not ask whether the room will be used year round or in cold months
  • The quote has glazing with no details on the glass type, the frame or the seal warranty
  • The roof-to-house joint has no flashing described, or the pro says it will be sealed with caulk only
  • The pro says a year-round room needs no heat or cooling

What you can do yourself

Clearing the site, removing an existing screen porch and choosing the flooring and paint are reasonable homeowner tasks. Foundation, framing, glazing installation, roof tie-in and any electrical or heating work should be done by licensed professionals under permit, because water and air leaks at these joints cause the most damage.

Licenses and permits

A sunroom addition often needs a building permit for the foundation, framing and electrical work, and roofing and heating work are often inspected. Check with your state or local licensing agency and your local building department before you start.

Sunroom addition questions

Can a sunroom be used in winter?

A sunroom can be made year-round with insulation, a proper seal and a heating system. A three-season room is built with lighter insulation and may be cold and damp in winter. Ask the pro to show the insulation and heat source for the use you plan.

Will glass make the room too hot in summer?

It can, without shading, ventilation and the right glass. Ask about low-emissivity coatings, the window orientation and whether a ceiling fan or cooling is planned.

Do I need a foundation for a sunroom?

Usually yes, for a room with a solid floor and a roof that carries load. Some prefabricated kits sit on a slab, but the local rules still apply. Ask the pro what foundation the design needs and why.

About this guide

This national guide is written and checked by infinibell. Rules and conditions differ by place, so local pros are credited on guides for the cities they serve, not on national ones.

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