Construction Methods and Materials
Although the focus of a finished sunroom may draw the eye up to the sky, sunrooms must start from the ground-up like any other construction.
- Types of Windows
- Window Options
- Energy Standards for Windows
A sunroom must have a foundation that complies with local building codes. To be deeper than the frost line, the footings for the foundation must typically be a distance of three to four feet below the ground. This ensures that the foundation does not move about when the ground expands and contracts as it freezes during the winter months.
If your yard is somewhat level or the spot for your sunroom can be leveled, it is best to build on grade using a slab foundation. This type of foundation works particularly well for most popular sunroom floorings (such as tile, stone, vinyl, carpet and many others) and can also allow the addition of radiant heating.
If your sunroom is not directly on grade, you will be required to build a conventionally framed foundation complete with concrete footings that comply with local building codes. The exterior foundation should have walls made of concrete or cement block. A framing system built from girders and joists along with a subfloor will bring your sunroom's foundation up to par.
With the exception of all-glass sunrooms and some prefabricated sunrooms, the roof of a sunroom is framed in a conventional manner using joists of the appropriate size, spacing and insulation.
Depending upon personal preference, conventionally framed roofs may include skylight openings. If skylight openings are included, the glass in the overhead glazings must meet requirements for safety specified by local building codes. Typically this means that tempered safety glass is used. Standard skylights and roof windows will already meet strict specifications for overhead glazing safety.
While the walls will primarily consist of glass, other components are important for the room's comfort, stability and appearance.
There are a variety of materials from which to choose for the construction of your sunroom's walls. To complement the glass of your gazing room, you may select from popular options such as wood, aluminum or PVC.
This is an excellent, highly insulated material that benefits from little or no external maintenance. It is readily available and well tested and the lowest cost option of all three materials. It is mainly seen in white but is also available in some other colors and styles, including woodgrain. PVC is the most popular material for sunrooms today.
For some, however, PVC lacks authenticity when it comes to the more traditional designs. It is generally not acceptable for use on historical buildings.
For a truly traditional design with an authentic look, wood is the popular choice. Just about any traditional conservatory design can be recreated and improved with the benefit of today's technology. While it will require some periodic maintenance, modern paint finishes and stains ensure that this is increasingly less of an issue. Available in a variety of stains as well as various painted finishes, this traditional material is actually quite versatile and, for many, it is well worth the money.
The features of this material are very similar to those of PVC, although it is generally a bit more expensive and does not insulate quite as well. When strength of structure is a major issue, such as commercial buildings, aluminum is a good choice.
To ensure that your sunroom is the comfortable nook that it should be for year-round enjoyment, proper insulation is necessary. Sunroom walls are usually framed conventionally with wood studs. To maximize the insulating power of your walls, you may want to use a higher grade of insulation and/or specify 2 x 6 (as opposed to standard 2 x 4) studs to allow a thicker space for the insulated portions of the walls.
Insulation is important, however, most of your sunroom walls will be glass. So selecting high-performance glazing is one of the most important choices for your sunroom. Glazing should be designed to generously collect sunlight when you need it, effectively block the most sunlight when you want to prevent it and to retain heat during cold winter months-especially at night.
Glass windows and doors are the primary components of any sunroom. Sizes, shapes and styles offered by manufacturers are almost without limit, allowing a great deal of creative latitude in design. It is wise, however, to choose windows that are compatible with the existing windows and overall architecture of your home. While finding a perfect match is not necessary, finding windows that work well with your home and complement it is important.
Fixed windows tend to be less expensive than styles that open, so a smart option is to combine a number of fixed windows with ones that will open. You can also save money on this expensive portion of your sunroom by staying with stock size windows rather than custom creations.
The makeup of windows varies as does the initial price and subsequent energy efficiency maintenance cost. Popular choices of windows include those cased in wood, vinyl, aluminum and clad combinations.
Wood windows and doors are energy-efficient and widely available. All-wood typically are the most expensive type of windows. Custom builds are usually available. All-wood will require periodic refinishing.
Superior energy efficiency. Moderate cost. Available in few stock colors. Maintenance free. Can be painted.
Not as energy efficient as most others. Maintenance-free. Should include a thermal break to slow transfer of heat.
Combines energy-efficiency of wood frames with maintenance free vinyl or aluminum. Moderately priced. Most popular style of window/door.
The most important component of a sunroom is, of course, its windows. Not only do they allow a clear view of the sun to come into your space, but they are also help to maintain a comfortable climate inside the room. By choosing windows that are properly designed and treated, your sunroom will remain comfortable even through the hottest summer days and the coldest winter nights.
Each manufacturer achieves the end-result with some differences in their approach, but the industry standard for sunroom windows is hermetically sealed, double-paned glass with an insulating dead-air space between the panes. With modern insulating capabilities and good clarity, this type of window is a good choice for most regions of the country.
If you live in an especially cold climate or have special concerns about the energy-efficiency and insulating capabilities of your windows, you may opt for specialty glazings.
These more expensive options include:
Triple-paned glazings - Includes three panes of glass to create two layers of insulation that prevent heat loss.
Argon-filled windows - The space between the panes of glass is filled with argon or another inert gas. Argon's thermal conductivity is about one-third less than that of regular air, so it provides better insulation.
Low-emissivity glass - Usually referred to as "low-E" glass, this type of window or door is coated with extremely thin layers of silver or other metal. The glass permits light to pass through but helps prevent the transfer of heat. This allows outside temperatures– whether too hot or too cold–to be kept out and inside climate control measures to be better retained. Because low-E glass also blocks a great deal of ultraviolet rays, can act as a "sunscreen" for you and your furnishings.
Safety glass - Required by most building codes for skylights, windows within 18 inches of the floor and windows installed on walls that sit at a 15 degree or greater incline, safety glass is either tempered, laminated or wire glass. The most popular is tempered glass. Tempered glass is heat-treated and when it breaks it crumbles into little pieces rather than large shards of glass.
For sunrooms that have a traditional framed roof instead of an all-glass topping, skylights can provide an extra amount of light and airiness. Simply because they are opened directly to the sky, they allow nearly twice as much light to enter the room as regular windows. Glazing options for skylights are similar to those of windows. The industry-standard is insulated tempered safety glass.
There are three basic types of skylights:
Fixed skylights - Cannot be opened. Most economical. May include "bubble shaped" insulated dome to help shed water.
Fixed and vented skylights - Include a small vent that can be opened. Less expensive than skylights that fully open.
Vented skylights - Open via hand crank, control rod or electronic control. Should be equipped with insect screen.
The National Fenestration Rating Council (NFRC) is an independent, nonprofit testing organization created by the window, door and skylight industry to create standards of energy efficiency that can be applied to all windows. The NFRC label provides the only reliable way to determine the window energy properties and to compare products. The NFRC label appears on all products certified to the NFRC standards and on all window, door, and skylight products that are part of the Energy Star program. At this time, NFRC labels on window units give ratings for U-factor, Solar Heat Gain Coefficient (SHGC), Visible Light Transmittance (VT), and Air Leakage (AL). Soon labels will include an annual heating and cooling rating (HR and CR).