Dear Jim: I should replace my old sliding glass patio door. I feel a draft and hear road noise through it, it sweats during winter and doesn’t slide smoothly. What features and options should I consider in a new one? – Ted K.

Dear Ted: An old sliding glass patio door, even if it has standard double-pane glass, can be one of the biggest energy wasters in a home. Air leakage around the door is often the worst culprit. This is particularly true during the summer, when warm, moisture-laden air leaks indoors through it.

You will be surprised at all the new features and styles available. The energy efficiency of the glass is as high as R-10 and airtightness is higher than ever. This also reduces noise from outdoors.

Security of patio doors, a common target of thieves, has also been improved dramatically.

Much design attention has been given to styling. French-(Freedom) style patio doors are increasingly popular. With wider rails and stiles on the door frame, these sliding doors are strong and simulate double-hinged ones. Optional matching grids can be added over the glass for more style.

Sliding glass doors cover a large span, so the strength of the frame is critical. Typical frame material options for replacement sliding glass doors are fiberglass, vinyl, wood, vinyl or aluminum-clad wood, and aluminum.

Fiberglass is one of the best materials for sliding glass door frames. This is made with a pultruded process, which is different from how boat hulls and car bodies are produced. Pultrusion combines long glass fibers with strong resins to create a very strong, almost indestructible, frame for the glass.

A fiberglass frame expands and contracts with temperature changes (hot summer sun to cold winter nights) at a similar rate as the glass panes. This reduces stresses within the door. For a wood appearance, select one with a real oak veneer over the fiberglass.

Vinyl is another low-maintenance material frame material to consider. Its color goes completely through the frame, so it looks good even with small scratches. Look for fusion-welded corners and ball-bearing steel or nylon rollers. Vinyl or aluminum cladding over a wood frame minimizes its outdoor maintenance. Aluminum frames should have a thermal break.

The type of glass is key to efficiency. As a minimum, select double-pane low-e glass. For hot climates, you may prefer to have one tinted pane. For cold climates, triple-pane low-e glass with krypton gas is most efficient.

A multipoint lock feature is good for added security. With a strong frame, this makes it difficult to pry the door open. Double-hinged doors, which resemble sliders, are also a good choice for added security and efficiency.

Write for (instantly download – www.dulley.com) Update Bulletin No. 939 – buyer’s guide of 15 fiberglass, vinyl and wood sliding-hinged patio door manufacturers listing sizes, glass options, colors, decorative and security features. Include $3 and a business-size SASE, and send to James Dulley, 6906 Royalgreen Drive, Cincinnati, OH 45244.