Q: One of the dual-pane windows in my kitchen nook has developed moisture streaks between the panes. My house is ten years old and this is the first time something like this has happened. Do I absolutely have to replace the window? Or can I wait until later in the summer after the moisture has dried out, then caulk around the inside and outside of the window? Or do you have another suggestion?

A: The complete window does not have to be replaced but the glass thermal pane unit does. Once seal failure between the glass has occurred, caulking the inside and outside of the unit will not stop moisture from penetrating into the unit. Subsequently, the unit needs to be changed.

If it is an aluminum window, your local glass company can change it out. But if it is a wooden window, you should contact a wooden window expert. Some brands of wooden windows are very tricky to take apart to replace the glass, and most people are unfamiliar with the proper technique to dissemble and replace the glass to prevent future seal failure.

Q: What causes seal failure between dual pane glass?

A: There are basically two causes of seal failure. One is constant soaking of water that is trapped under the glass unit, which breaks down the sealant between the glass. The second cause, which I believe is the most common reason for seal failure in aluminum windows, and especially in wooden windows, is that moisture is allowed to penetrate through the sash and is trapped under the thermal pane unit, at the bottom. Those few nights that we get in the winter when it freezes, the moisture under the unit freezes and expands, subsequently popping the seal between the two panes of glass.

On aluminum windows, not much can be done to prevent that problem. But on wooden windows, a top quality semi-glass latex enamel paint should be applied to the sash, with 1/6 inch minimum paint onto the glass. Getting the paint on the glass will seal the sash to the glass and not allow moisture to penetrate into the unit.

Q: I'd like to replace the aluminum sliding door with double French doors. Is there anything I should take into consideration in making this decision?

A: Double French doors are beautiful and very appealing, especially when we see them in magazines but they are not very practical. One drawback is that when you want to leave the doors open, they take up wall space where you may already have furniture. Also, French doors do not lend themselves to having screens, which is another drawback. If the doors are directly exposed to the rain, it is difficult to seal them perfectly to keep the weather out.

A great alternative to double French doors are center swing patio doors. They look exactly like two French doors sitting side by side, but one side is fixed and cannot open. The other door swings open back against the fixed panel instead of taking up wall space. Not only do most brands of center swing doors come with a sliding screen, but they are also less expensive than double French doors.

If the doors are exposed to severe weather, the center swing doors offer a better and tighter weather seal than double French doors. Also, most companies offer aluminum or vinyl clad exteriors for maintenance free operation on the outside while the inside of the doors are wooden, which can be painted or stained to match your interior decor.

by Kathy Maynard, reprinted courtesy of HomeAdvisor.com