• offers excellent strength and energy efficiency
• can be painted or stained to match any color scheme

Problems:
 

• most solid wood windows are only available in standard sizes; non-standard sizes must be custom-made and are generally more expensive
• requires more maintenance over its lifetime than other materials

 
Aluminum  
 
Benefits:
 

• relatively inexpensive
• easy to maintain

Problems:
 

• aluminum is a conductor of heat rather than an insulator, which means the area around the window will feel cold as heat escapes through the frame (although some manufacturers may incorporate a "thermal break" or plastic strip inside the frame to act as an insulator)

NOTE: If you're considering aluminum, check with your local building inspector or utility company. Since January 1994, many states and municipalities have imposed restrictions affecting the use of aluminum windows.  
 
Vinyl  
 
Benefits:
 

• a better insulator than aluminum
• easy to maintain
• available in a limited number of solid colors and printed patterns

Problems:
 

• may not offer an acceptable match to existing woodwork in older homes
• may shrink and expand when subjected to low and high temperatures (which means that, over time, air and water may leak around the window)

NOTE: Some vinyl window manufacturers have begun inserting metal reinforcement into parts to combat shrinking and expanding, which reduces energy efficiency.  
 
Clad Wood  
 
(wood window frames clad with aluminum or vinyl coverings)  
 
Benefits:
 

• offers the energy efficiency and beauty of wood with easy maintenance

Problems:
 

• many are only available in a limited range of standard sizes; non-standard sizes may be expensive
• construction can be questionable, so look for a manufacturer with established credibility who will stand behind the product

 
 
Fibrex™ Material
Renewal by Andersen's unique frame material that combines the strength and durability of wood, with the easy maintenance of vinyl.  
 
Benefits:
 

• resistant to temperature changes, so it won't expand or contract much in heat or cold
• resistant to bowing and cracking, which can cause drafts and water leaks
• an excellent insulator-about 700 times better than aluminum
• won't rust, rot, peel or blister