Water forms between panes of glass

Q.     Water has formed in between the panes of glass of a window in my house, which is about 12 years old. I hope you can provide a solution for this.

A.    Water or any form of condensation between the panes of an insulated window means that the seal is broken. There is no other remedy beyond replacing the sash or the glass; it depends on which is easier and less expensive.

Moisture builds up after new windows installed

Q.  I live in a 40-year-old ranch and had new windows installed 3 years ago. Since they were put in a fair amount of condensation builds up within the house during the winter months. I run a dehumidifier to cut down on the amount of moisture build up on the windows but it still persists. The bottom of the windows have become dark with mold where the wood meets the glass.

Condensation inside new windows
Condensation inside new windows

Any suggestions on how to get more air circulation in the house to eliminate the excess moisture?

A.  Your old windows were quite leaky, allowing more air exchanges than the new ones. So moisture generated by your family and its habits (the number of people living in the house, the house size, length of showers, type of cooking, etc.),  water-loving plants, pets, firewood stored in the basement, clothes dried on racks, etc.) will accumulate and, when the dew point is reached on the window glass, condensation occurs.

You need to lower the inside relative humidity by changing some of the things that keep it too high. Ventilate the house often by opening windows on milder days, or run bathroom and kitchen fans for long period of time (be careful, though that the use of the fans depressurizing the house does not cause backdrafting of the heating appliance — this would draw carbon monoxide into the house.)

Or you can choose to have one or more room-size air-to-air heat exchangers, or a full-house one, installed.

Meanwhile, remove the mold on the bottom rail of the window sashes with a toothbrush dipped in a mixture of equal parts household bleach and water.

Water collects inside of windows in winter

Q.   I hope you might be able to shed some insight on a problem I have with my windows. As soon as it gets cold, beginning sometime in October until the weather warms up in the spring, water collects on our windows and forms long puddles along the bases, where the glass meets the wood. We have storm windows as well as new insulated windows but this problem persists.

First thing in the morning, I open my curtains and wipe up the water. Opening the curtains does not solve the problem, but it helps in most of the rooms of my house. Anyway, I fear that my windows will all be rotting soon if I don’t resolve this perplexing problem. Do you have any ideas about what is causing this massive amount of condensation and what I can do to prevent it?

A.    Drawn window shades at night will cause condensation on glass, especially if the shades are of the insulating type. The air trapped between the glass and the shades is cooled, and the dew point is reached.

The fact that you have such a serious condensation problem in spite of having insulated windows and storm windows is an indication that there is too much moisture in your house. If you didn’t have this problem before having new windows put in, it is because the old windows were leaky and allowed greater exchanges of air in the house. The new windows are obviously tighter and the number of air exchanges is greatly reduced.

If you have a warm air system and there is a humidifier on your furnace, and you are using it, I suggest that you shut it off, empty it and clean it with a bleach solution. Make sure that it is dry.

You should also look at your lifestyle and see if there are things you can do to reduce the relative humidity (RH) in the house.

For instance, do you dry laundry on racks inside the house, or is your dryer properly vented to the outside? Do you have lots of water-loving plants? Is your house modest in size with several children and pets? Is your cooking generating a lot of steam, and is it with gas? Does your family take long, hot showers? Store firewood inside?

If there are things you cannot change, you might want to look into an air-to-air heat exchanger.

Reducing maintenance with new siding and windows

Q.  You have written that we should take the cedar shakes off before re-siding. Would it be more insulated if the siding is put over the shakes? As a widow, I would like to eliminate maintenance. I would like to replace the windows also so there is no upkeep. Vinyl or aluminum?

A.  Cedar-shake siding is quite irregular and makes things difficult when trying to apply vinyl siding smoothly. You will get more insulation if the shakes are removed, and 1-inch thick rigid extruded polystyrene (XPS) insulation is installed directly over the sheathing.

If your question is whether to have vinyl or aluminum siding put on, the decision is very much up to you and the local market. Vinyl siding represents the bulk of the installations nowadays and, when properly installed by experienced workers, it is a good and long-lasting, maintenance-free siding.

So is aluminum, although it is not as popular as it was decades ago, and you may not find it available in your area. I would urge you to insist on XPS insulation (blue, grey, green or pink) instead of accepting the type of thinner fold-up material some installers will offer you; it is not as effective an insulation, but the dealers like it because it goes up faster.

The windows are also somewhat of a local matter — whichever is most popular in your area: aluminum or vinyl, just make sure that it is a top-quality product. I have worked with clients who had bought lesser-quality vinyl windows, and were beset with cold-air infiltration as the vinyl shrank in cold weather — a tremendous loss of energy. The windows may have looked like they were tight in the store, but they did not perform well once installed.

It is recommended that you get three estimates from reputable contractors, but the most important thing you can do is choose a contractor who has an excellent reputation for quality work, presents you with a clear and detailed contract that stipulates the type of material to be used, a start and finish date, and who follows up quickly on any punch list items (they are almost unavoidable in construction.) Ask for several references of people whose jobs were done recently, one and two years ago (two names for each category), and call them.

Keep in mind that choosing the lowest price is often not the best in the long run.

Do not agree to pay anymore than 10 percent at contract signature with the balance due at satisfactory completion. Anyone who asks you for half or more of the money “to pay for the materials” should arouse your suspicions. Also check with the Better Business Bureau and the consumer protection division of your state’s attorney general to see if there are any unresolved complaints against the contractors you are considering.

Windows painted shut

Q.   Help! We had a painter paint the outside wooden frames of our windows. Now we find that the windows are painted shut. What can we do to correct this? We need a solution, if we are to take care of this ourselves (we are in our 80s).

A.   You should insist that the painter come back and free the windows for you. He or she does not seem very professional or experienced to leave you with this problem. People your age should not have to climb ladders and unstick windows!

However, if you can’t get the careless painter to take care of freeing the windows, you can buy a special tool for the purpose in hardware stores; it has a handle and a thin serrated blade with sharp teeth and two sharp points.

Window Zipper
Tool to open windows that were painted shut

The blade is worked between the window frame and the sash and is either drawn and/or wiggled (whichever is appropriate) down the length of the sash. This cuts the paint bond out.

If you are not physically able to do the job, hire some local high school or college youngster to do it for you; it’s quite strenuous.

Mold in the window casings of a tight house

Q.    We built our home and have lived in it for 4 years now. The contractor is very environmentally minded and created an exceptionally tight house. It seems that during the colder months, we develop mold on the wood casings of our windows during the nights, especially the ones with blinds or shades.

We’re very concerned about the “rot-factor”, and, more importantly, the baby seems to have developed an allergy to the mold. Can you let us know how we can cure this problem, regarding both air-quality and wood preservation?

A.    The blinds and shades trap ambient moist air between the blinds and the windows. During the night, this air cools and its relative humidity increases to the point where it encourages mold growth.

You could leave the shades and blinds up to see if this solves the problem. But it sounds as if you need an air-to-air heat exchanger. This can be a whole-house system or one or more individual room units, depending on your house design.

Building 2nd-story deck without blocking sun

Q.  I have purchased your book after following your posts with great interest; it is a very valuable resource for homeowners.

We just moved recently in a house on a sloping lot; it is two-story house in the back, but only one on the street side.

My question is about how can I build a deck on the back of the house? Building it across the entire back of my house, as I would like to do, will block sunlight to the lower level, which faces south and is finished and lived in.

A.    There are two possibilities. If the lower level only has a few windows, you can leave portions of the deck that would block the sunlight open. Make the openings wide enough to allow sunlight as the sun travels across the horizon. A railing will need to be built around these openings.

But if the majority of the lower level has many windows and sliding patio doors, the best option would be to build the deck away from the house and connected to it with a bridge. This is probably the best way to go about it anyway, and it can be made quite attractive and interesting.

Frost on patio door

Q.    I installed a new Marvin French patio door in late summer. This is their Ultrex product with wood on the interior. In the fall, I began experiencing condensation on the outside of the stationary panel first thing in the morning. Doesn’t seem to be an issue with the operating side.

I have contacted Marvin customer service and was told this is not a defect but simply a result of the climate change from summer to fall and it should go away when the real cold weather arrives. I would appreciate your opinion on this issue.

A.    As cooler fall weather arrives, it is common to experience condensation on the outside of insulated glass in the morning because the air is very humid. Later on–as you have probably noticed by now — the much colder air of winter is drier and the glass is warmed by the heat in the house. This prevents condensation. You do not see it on the operating panel because you may have the screen in front of it — it provides some insulation.