You can cut off the material that is oozing out, but don’t cut it partially off and then yank on the loose material to remove what’s left, said a spokeswoman at Peninsula Glass in Port Hadlock, Wash. Doing so could remove the part of the foam that is still working, and you might create an opening where the window could leak.
Keith Sitzmann, owner of Sun Spaces in Redmond, Wash., suggested removing the oozed-out material by cutting along the frame with a utility knife cocked at a 45-degree angle. That would eliminate the risk of cutting into the vinyl or compromising the part of the foam that’s still functioning. Then make a second cut, this time with a single-edge razor blade held flat to the glass, to free the excess foam. It helps to have the razor blade in a holder, such as the Stanley mini razor blade scraper ($2.59 at Ace Hardware).
You’re also dealing with mildew on the vinyl window frames and the wood trim. You can probably just wipe the mildew off the vinyl with a damp cloth or sponge, or one moistened with water and a little dish detergent. Vinyl isn’t porous, so the mildew should come right off. If you want to kill the mildew, add some white vinegar or chlorine bleach to the water (wear gloves if you use bleach). But killing the growth or the spores on the surface doesn’t really add much long-lasting protection against having the mildew reappear, as plenty of live replacement spores are sure to be floating in the air. Mildew will grow when conditions are right — meaning if there is moisture and a food source, which can be something as simple as settled dander and dust.
The picture you sent shows significant stains on the wood trim around your windows. After looking at the picture, Sitzmann said many people might see the stains as a clue that the windows are leaking. To test whether that’s true, you could poke at the wood with the tip of a screwdriver to see whether the wood is soft and spongy, a sign of rot. If you find that, call in a contractor to assess the situation.
But it’s more likely that the wood stains are a cosmetic issue, caused by excessive condensation in the room. This kind of staining is especially common in sunrooms built with Western red cedar in the Pacific Northwest, where the relative humidity is generally high in the winter. Cedar is high in dark-colored, water-soluble chemicals, some of which help make the wood rot-resistant.
Even if it’s cool and cloudy outside, sunlight heats up a sunroom during the day. The warm air can hold a lot of moisture. But at night, when the space cools, the moisture condenses and soaks into the wood enough to cause the extractives to drip down. Over time, the wood looks blotchy. White patches indicate where the extractives leached out; dark areas are where they collected. And the black spots are where the wood stayed damp long enough for mildew to grow.
You probably can’t just wipe the wood free of mildew. You need something that penetrates better. One solution is hydrogen peroxide. To even out the color of the wood, you could try oxalic acid, such as Savogran wood bleach ($12.99 for a 12-ounce tub at Ace). But you’d need to work in sections to ensure that you can rinse the residue thoroughly as soon the color is evened out.
If you’re dealing with a lot of trim and possibly even paneling, staining the light areas would be easier. You might want to use a product such as Saman wood stain, which comes in numerous colors ($15.50 for 12 ounces). This stain is water-based and doesn’t require pre-sealing the wood with a wood conditioner. Rub it in with a sponge and wipe off the excess. Any that you get on the vinyl window frames wipes off easily, as long as you do it promptly.
To keep mildew from regrowing and the blotchiness from reappearing, you need a way to keep condensation from forming, such as an exhaust fan or a dehumidifier that switches on automatically based on temperature or relative humidity. You might need to experiment to figure out the best setting.
