The 6 Most Important Things to Remember When Comparing Wood Windows


You’re looking at a wood window, so let’s begin with the most appropriate section…the wood interior. Most wood window manufacturers use a variation of pine as their standard species. Pine is a light-colored wood that accepts stain and paint well. Optional wood species are usually available but pine is by far the most popular.

If you truly are interested in buying a wood window, don’t settle for a window that is made up of mostly aluminum or fiberglass with mere wood slats applied to the interior for a wood window effect. Ask to see a cross-section of the window(s) you’re viewing so you can really see the amount of wood contained in the window. This will be the tell-tale indicator of how faithful the manufacturer is to making a window out of wood.


There are 3 options to wood window exteriors. They are: Aluminum cladding, Vinyl Cladding, Bare Wood (No cladding)

  1. Aluminum Cladding: An aluminum clad exterior has many assets. It’s virtually maintenance-free, it can be painted any color you want, and it offers extremely sturdy protection to the exterior of your window. But you have to be careful what type of aluminum you’re getting. Extruded aluminum is much thicker, more solid and usually a bit more expensive than roll-form aluminum, which is thinner, flimsier and usually priced less. If you’re looking at cross-sections, the difference between extruded aluminum and roll-form is easy to see. The disparity in strength would be similar to the difference between a metal pipe and an aluminum can. There is a drawback with aluminum cladding in that it is slightly more conductive than vinyl cladding, thus making it faintly less energy-efficient.
  2. Vinyl Cladding: Vinyl cladding’s assets include the fore-mentioned fact that it’s performs better thermally. For many years, one of its biggest drawbacks was that it was limited in color options but advances in paint made specifically for vinyl are allowing for more exterior colors for vinyl cladding. However, not many companies offer this option. Vinyl cladding is also not as solid and rigid as aluminum.
  3. No Cladding: Wood windows with no cladding on the exterior are very popular for historic homes and neighborhoods where historical replication is king. These type of windows can obviously be painted any color because you’re applying it directly to a wood surface. The biggest drawback is that over time, Mother Nature plays havoc with the exterior and you will have to continually maintain them. Depending on where you live, what type of weather you incur, and the strictness of your local building or home association codes, you may have to re-paint the exterior as often as every 2-3 years to protect the wood from aging and maintain the look required.


It’s quite easy to compare energy-efficiency thanks to the National Fenestration Ratings Council® (NFRC). See left.

The NFRC is a non-profit organization created by the window, door and skylight industry. Its primary goal is to provide accurate information to measure and compare the energy performance of window & door products. While the NFRC does NOT distinguish between a “good” window and a “bad” window, set minimum performance standards or mandate performance levels, it has directed window & door manufacturers to display their product’s performance by implementing the use of stickers on residential windows and doors.

A typical “NFRC” sticker looks like this. See right.

It allows you to easily compare the performance levels of competing windows. An NFRC sticker contains 4 categories and corresponding test values. While each category has an official definition, here are the laymen’s descriptions.

  1. U-Factor: This is also known as the U-Value. The U-Value measures how well a window or door prevents heat from escaping. Remember: Lower is better when comparing U-Values.
  2. Solar Heat Gain Coefficient (SHGC): SHGC measures how well a window or door blocks heat caused by sunlight. SHGC is expressed as a value between 0 and 1. Remember: Lower is better when comparing SHGC.
  3. Visible Light Transmittance (VT): The VT measures how much light comes through a window or door. VT is expressed as a number between 0 and 1. The higher the VT, the more light being transmitted.
  4. Condensation Resistance (CR): CR measures the ability of a window or door to resist the formation of condensation on the interior surface of that product. CR is expressed as a number between 0 and 100. Remember: the higher the CR rating, the better.

It’s important that when you use the NFRC sticker to evaluate windows, that it’s a true “apples-to-apples” comparison. Don’t compare wood windows with vinyl windows. Don’t compare windows with doors. Most importantly, don’t compare a window with standard glass to a window that has specialty or Low-E glass. Different glass types can make a huge difference in the values shown on the sticker and can skew the comparison. Always check the NFRC sticker. It will tell you the glass make-up of the product you’re assessing. If you’re not sure, ask.


If energy-efficiency is your top priority, look for products that carry the Energy Star® label.

Energy Star® is a government-backed program helping individuals protect the environment through superior energy efficiency. Two categories make up Energy Star® window and door requirements; U-Value and Solar Heat Gain Coefficient (SHGC).

Energy Star® divides the United States into 4 different climate zones. Those zones and their respective requirements are as follows:

As you can see, Energy Star® levels vary depending on where you live so make sure you know the zone in which you are located. Also keep in mind that some areas of the country require Energy Star® status so you will probably want to check your local building codes.



Warranties are different so make sure you fully understand the coverage being offered to you. These are the questions you should ask:

  1. What kind of warranty is it? Window warranties are presented in a couple ways. (a) Broken down by window component (glass, paint, hardware, etc. (b) Given as “whole window”, meaning everything from top to bottom receives the same coverage.
  2. How many years are the coverage?
  3. Is it a “non-pro-rated” (manufacturer’s liabilities remain constant throughout the life of the warranty) or is it “pro-rated” (manufacturer’s liabilities gradually decrease during the life of the warranty)?
  4. If you sell your home, is it transferable to the next homeowner(s)?
  5. Some wood window manufacturers offer painted interiors. If this is a product you’ll be purchasing, ask how long the painted finish is covered.


The old adage “You get what you pay for” is usually very true when it comes to wood windows. There are many wood window manufacturers and pricing on seemingly similar windows from two different manufacturers can fluctuate quite a bit. There’s usually a reason for this price variation. When all is said and done, make sure you don’t short-change yourself by basing your choice solely on who has the lowest price.


National Fenestration Ratings Council®

Energy Star®

American Architectural Manufacturers Association