Considerations for a Four-Season Sunroom Addition

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There's no feeling quite like bathing in natural light as you enjoy your morning cup of coffee or the vivid colors of sunset. However, extreme cool or hot weather as well as mosquitoes, flies and other pests can make this dream unrealistic for much of the year — unless, of course, you have a four-season sunroom.


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This type of sunroom is a room lined with windows that's insulated and is served by heating and/or cooling equipment. This lets you comfortably enjoy the beauty of the great outdoors all year but without actually experiencing any of the inclement weather. However, before you decide to invest in this expensive but rewarding home addition, there are some important factors you should first consider.

The Right Type of Sunroom

Four-season sunrooms, also known as four-season rooms, all-season rooms or even Florida rooms, are a welcome home improvement project for many homeowners, but they're not the right choice for everyone. If you live somewhere with mild winters or summers, you might be better off with a three-season sunroom or a solarium.

A three-season room is similar to a four-season room in that it has large windows on three walls, but because it is not designed to be heated or cooled (and is not insulated and weather-tight), it cannot be comfortably used in extreme heat or cold. That being said, if you live somewhere without particularly cold winters or hot summers (or if you don't plan to use your sunroom during those times), you might be happier with a three-season room addition since they cost much less than a four-season room. It's worth mentioning that these living spaces still work well to keep out wind and rain, and many are equipped with fans or space heaters to help with moderately hot or cold weather.

A solarium is another type of home addition only its focus is to let in as much natural light as possible. As such, they are made with floor-to-ceiling windows and glass ceilings, whereas four-season rooms generally have solid sections of wall that reach up to knee or waist height, and they have traditional roofs, possibly with skylights to bring in additional natural light.

While the windows in solariums often have low-e coatings to limit heat gain and the rooms may be fitted with heating and cooling systems to keep them more comfortable, the sheer amount of light entering the room can often make them unpleasantly warm in the summer. This is not a problem for people living in cool climates, but for those in hot climates, a four-season room is usually preferable.


Materials for a Sunroom Addition

Given that one of the defining features of a four-season sunroom is its ability to stay warm in winter and cool in summer, it's hardly surprising that the materials are one of the most important things to consider when it comes to a sunroom addition. Whereas solariums are mostly made of glass, and three-season rooms are made from cheaper materials like screen porch panels, four-season rooms need to have good insulation, which is why they should be made from higher-quality materials. The three most common materials used for sunroom additions are vinyl, aluminum and wood.

Vinyl is the most popular material for sunrooms because aside from being a good insulator, it is inexpensive, impervious to moisture and insect damage and is also low maintenance. It comes in a wide variety of colors, so it can match most home exteriors without looking like an addition quickly slapped on the outside of the house. Look for vinyl that is "multiwalled," meaning it has aluminum or steel reinforcement to provide additional strength.

Aluminum is stronger than vinyl but has not historically been used for sunroom additions because it is more expensive and is not a good insulator on its own. In modern times, though, manufacturers have drastically improved the insulation properties of aluminum by adding composite materials, and it has since become a more popular option. Many sunrooms use both vinyl and aluminum to take advantage of the strength of aluminum and the insulation of vinyl. Aluminum is particularly common in frames and roofs, where it can add much-needed strength.

Wood is also a popular choice for sunrooms since it provides for the most versatility of design, can easily match the design of the rest of the home and can even be fitted with stone or brick facades if necessary. Unfortunately, the material is prone to rot and termite damage, and it may require upkeep, such as repainting. Wood sunrooms can be far more expensive than vinyl or aluminum, often costing close to the same amount as any other home addition.


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Windows in a Four-Season Room

The windows are particularly important, as a single-pane window provides very little insulation, which makes the room less comfortable and also results in lower energy efficiency and higher energy costs. A four-season sunroom should always use double-paned windows that are silicone double-sealed. Ensure they are labeled as having safety glazing, as this means they'll be the least dangerous if they break — plus, most building codes require this.

Additionally, the windows should be ENERGY STAR rated to your climate so they can retain heat in the winter, keep in comfortable air all year long and block out heat from the sun in the summer. Heat retention is rated by its U-factor, with lower numbers indicating less heat loss. In all areas of the country, window U-factors should ideally be below .40, but in all areas aside from the far South, it should be below .30. Windows that keep comfortable air inside the home throughout the summer and winter are given an air leakage certification (AL).

Heat from the sun is measured with a solar heat gain coefficient (SHGC), and again, the lower the number, the less heat can enter through the window. In Northern regions, it's fine to have any SHGC rating, as a little heat from the sun can make homes more comfortable in the summer and winter. In warmer areas, a SHGC rating should be below .25 to keep excessive heat out of the home during hot summer months.

ENERGY STAR rates windows according to climates, as retaining heat in the winter is less important in the far South areas of the U.S., while areas in the far North may not want to block out heat from the sun even during the peak of summer. As such, you should first research the area into which ENERGY STAR has sorted your location (Northern, North Central, South Central or Southern) and then look for windows that are rated for that region. All windows rated by ENERGY STAR have AL certification.


Windows reduce heat loss and air loss and block the sun using a number of different technologies. These include:

Heating and Cooling Systems

Of course, in extreme weather, insulation only goes so far. That's why it is so important to have a good heating and/or air conditioning system in your four-season room. While many people want their new home addition to be connected to the existing HVAC system, that's not always practical or affordable, so sometimes, it's best to add an independent system.

Expanding your ductwork to your new home addition will cost anywhere between $4,000 and $6,000. Alternatively, you could use a ductless minisplit system that will run around $3,000 on average and won't require any new ductwork. On the cheap end, you can instead add a window A/C unit and wall-mounted heaters, but these can be much less efficient than permanent heating and cooling systems.

A few other options you can incorporate to improve the comfort of your room include:

  • Choosing both windows and skylights that can open to let in cool air on warm days.

  • Installing ceiling fans with forward and reverse speeds to move air around the room.

  • Adding window treatments that can be raised and lowered along the entire length of the windows to provide shade on hot summer days.

Choosing a Sunroom Location

Many people choose to install their sunrooms on their back porch, but that's not always the best location. In Northern climates, a south-facing sunroom can be beneficial because it allows the most sunlight to enter the room every day. On the other hand, in Southern areas, southern exposure can result in too much heat entering the room, which could increase your energy bills.


North-facing rooms are often too dark and chilly in cooler climates, but they are ideal in warmer areas. East-facing rooms are good for providing sun in the morning and shade during the hot afternoons, whereas west-facing rooms may need additional shade in the afternoon.

Finally, don't forget that sunrooms have a lot of windows, which can mean less privacy. You may want to put the room somewhere that's not as visible to your neighbors or else invest in quality window coverings.

Image Credit: Perry Mastrovito/Image Source/GettyImages

Costs of a Four-Season Sunroom

The costs of adding any sunroom to your home will vary dramatically based on the size, materials, contractor, design and even your location. Overall, expect the budget for your four-season room to be between $25,000 and $80,000, with the materials costing between $15,000 and $60,000 and the labor coming out to somewhere between $10,000 and $20,000.

These estimates are just for the basic room addition without any extra aesthetic interior design elements such as paint, wallpaper, furniture or flooring (many sunrooms just have concrete flooring). Expect to add anywhere from $200 to $9,000 for enhanced design and decor details and even more if you plan to use any luxury materials or brands.

It's worth mentioning that there may be other unexpected costs involved with your new home addition as well. These can include increases in your property taxes, insurance rates and utility costs.

Return on Your Investment

Sure, you'll likely enjoy a four-season sunroom, but a $25,000 to $80,000 addition is a big expense for just about anyone. There's a silver lining: Four-season rooms provide a great return on investment of about 48 percent. That's not just because people like to have a sunroom in their home but also because a four-season room is generally cheaper than a conventional construction addition to your home but still counts toward the overall square footage of the home. In fact, a four-season room is the only sunroom addition that adds to the square footage of your home since it has heating and cooling, making it essentially another room and not just an outdoor area.


Choosing a Good Contractor for a Sunroom Addition

When you get contractor bids, you may notice these companies charge widely varying rates for their work. In general, while a higher-than-average cost doesn't mean you'll get higher-than-average work, a contractor who charges far less than the competitors may cut corners or leave out necessary expenses, so be wary if a price seems too good to be true.

Before hiring a contractor, first see examples of their work, check their reviews, look up their reputation with the Better Business Bureau and ask to see proof that the contractor is licensed and insured. Also, always get a detailed estimate and make sure it includes all aspects of the construction process, including obtaining building permits, arranging inspections, performing electrical work (or hiring an electrician), removing debris and site cleanup.

Your estimate should also include terms and conditions of the work, and the contractor should be happy to tell you what to do if you aren't satisfied with the work or if something causes a change in the estimated project cost. Remember to ask about the company's warranty, as most sunroom contractors offer comprehensive warranties, and if one doesn't, this could be a red flag.

Finally, remember to ask your prospective contractors how long they expect the project to take, as a four-season room may take anywhere from two months to seven months depending on the project's complexity.



Jill Harness is a blogger with experience covering architecture, design and decor trends from around the globe. As she lives in what would politely be called a "fixer upper," she is particularly interested in writing about DIY projects and repairs. Most of her home design writing can be found at You can find out more about Jill's experience and learn how to contact her through her website,