How To Build a Successful Sunroom

A sunroom can provide you with a small oasis in your home and help you lower your heating bill. But there’s a lot to consider if you want to create one for yourself. Here are some things to keep in mind during the planning process.

For a nation that faces lethally-cold weather at least one-third of each year, sunrooms are a valiant attempt to correct one of life’s many imbalances. But how well this actually happens depends in large part on your diligence as a homeowner. If you want satisfaction, it’s necessary to do some logical thinking before you go ahead with any sunroom project.

Sunroom Expectations

Begin by asking yourself a key question. Exactly what do you expect from a sunroom?

  • At one end of the spectrum you’ll find so-called “three-season” spaces. They’re comfortable in spring, summer and fall, with room for some furniture and seasonal plants.
  • Mid-way along the sunroom continuum you’ll find conservatories and greenhouses — places that can be a little too warm for people at times, but just right for heat-loving plants.
  • The hottest end of the spectrum is where you’ll find year-round sunspaces designed entirely to capture heat. These passive solar collectors are sometimes too hot for plants or people, but they lower your heating bill if built well and managed with care.

Year-round Sunrooms

  • Understand right from the start that sunrooms designed for year-round use may increase your heating costs, even with an ideal south-facing orientation.
  • How much extra you’ll pay in utility bills depends a lot on how much, and how often, you turn on the heat, and how much you pay for your sunroom.
  • Top of the line sunroom installations can cost $300 per square foot, though you will pay less for simpler, three-season structures.
  • You also need to understand that good sunroom design isn’t just about staying warm in winter, either. It’s also about keeping cool during summer months.
  • Pay special attention to glazing when selecting a sunroom, especially when it comes to heat control.
  • If you’re in a plain-glass structure, like those old-time greenhouses, then summertime temperatures can rise as high as 160F. But this can be controlled with coated glass that reduces heat build-up during warm months while decreasing heat loss during winter.
  • If you’re looking for comfort, remember that it’s technically easier to heat during the winter than it is to cool during the summer.
  • Current top-of-the-line glazing carries an insulation factor of R-14, though the average is about R-5. Rooftop coatings reflect 85% of incoming summertime sun, and wall glazing are designed to reflect 50% of the sun’s heat.

Sunroom Aesthetics

There’s something else you need to realize, something I didn’t think about until I scanned dozens of sunroom images for this article. Pay attention to aesthetics. As I’ve discovered, a few sunrooms look good from the outside, but a surprising number look pretty ugly. If all you plan for is performance and intended use, then you might end up paying tens of thousands of dollars for an energy-efficient backyard eyesore.

One simple tool for avoiding aesthetic disappointment is a scale drawing.

  • Take a picture of the side of your home where the sunroom will go, have it blown up to 8×10, and then photocopy it several times.
  • Now you can draw and cut out various sunroom shapes in thin cardboard or coloured plastic sheets.
  • Place them over the image of your home to get a visual sense of what you’re in for.


Always ask for customer references and follow them up before choosing a sunroom contractor. This work is technically challenging and it takes a dedicated specialist to succeed. Do your homework right and all you’ll have to worry about is the what novel to read the next time freezing rain and snow keeps you indoors in your warm, bright space.

If you’d like to hire a local, pre-screened general contractor to help you build a sunroom, find them on casaGURU.

Nuts and Bolts of Sunroom Success

As you’re planning the design and location of a sunroom, keep these tech-tips in mind:

  • Ask prospective sunroom contractors for a heat loss calculation on all the building options you’re considering. Leading-edge suppliers will have computer models to do this. Heat loss numbers are necessary for designing an effective sunroom heating system.
  • Understand that a sunroom could increase the need for mechanical ventilation in the rest of your house. Plants can add a lot of moisture to the air.
  • If your sunroom is to be built on a concrete slab, insist that it be insulated underneath with at least 2 inches of extruded polystyrene foam.
  • Plan a sunroom heating system that’s independent from the rest of your house.
  • If you’ll be using the space only occasionally during winter, choose an option that heats quickly and emits radiant heat slowly over the entire day. A sealed, gas-fired fireplace is ideal in this application. For continuous wintertime heating, radiant in-floor heating is ideal.
  • Sunroom glazing tilted 10 to 15 degrees steeper than site latitude maximizes wintertime solar heat gain, though that also means a potentially warmer sunroom during summer.
  • Include a fan for circulating air within the sunspace.
  • Plant deciduous trees outside to lower excess heat build-up during summer, while still allowing nearly full sunlight during winter.

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