Q: We have Marvin Integrity windows with wood interior installed in our home in Vermont. I have noticed during the winter that moisture appears on the bottom of both the upper and lower sash -- I have even seen some ice in extreme cold. We're wondering what causes this and if there are steps we can take to mitigate how much it occurs. The windows are 9 to 10 years old. This question came to mind as we are in the middle of refreshing the stain and poly protection. -- Vermont, via email
A: Marvin Integrity windows are very energy-efficient; if there is condensation on the sashes in cold weather, and even ice formation, it sounds as if you have excessive relative humidity (RH) in your house.
Examine your lifestyle and see if any of the following apply: keeping the indoor temperature below average (below 70 [[[degrees Fahrenheit); using a humidifier in a furnace or as a separate unit; small house with four or more people and/or pets; long, hot showers; steamy cooking; hanging wet clothes on racks; unvented bathrooms, kitchen and dryer; lots of water-loving plants; storing firewood in the basement; bare earth crawl space or cellar; etc.
Take care reducing moisture emissions from any of these sources. You may also need to consider an air-to-air heat exchanger.
Q: Our semi-contemporary house has cathedral ceilings on most of the roof. The original roof was replaced in 2005. It was a clean re-roofing job. The decking was found to be in good condition, except for some loose nails.
Owens Corning 50-year architectural shingles were selected, with added attic ridge vents. Ice and water shield was specified at leading edges (6 feet), and 15-pound felt for underlayment for the remaining roof. Chimney flashings were replaced, but not the head wall flashings.
Around 2009, during a heavy rainstorm, I noticed some water dripping from the window frames in the master bedroom. I climbed onto the roof to inspect, but did not find any obvious problems with shingles or flashings. However, I suspected the problem might be the flashing at the head wall. This flashing had not been replaced with the re-roofing; the workers simply pushed the new shingles under the original flashing.
On a warm day, I smelled a musty odor in the loft area. Also, the Sheetrock on the head wall at the joint to the roof felt warmer than the rest. I concluded that the head wall flashing needed to be replaced and the head wall opened to investigate. However, before I do this, I would like to have your expert advice and recommendations.
Enclosed is a cross-section sketch for the insulated roofs and walls and provision for ventilation. All cathedral ceilings have R-30 fiberglass bat insulation installed between the rafters, with a vent channel against the roof deck. Roofs have a 2-foot overhang and continuous soffit vents. The attic section has wall vents at both ends. Ridge vents were added in 2005 with the re-roofing. The MBR roof connects to a head wall, which has four awning windows.
Therefore, even with venting channels in the cathedral ceiling, possible vent airflow through the head wall to the ridge vent is blocked by the awning window framing, except at the center and the two ends of the wall, so this roof section is essentially unvented.
I also have enclosed a sketch of the concept for installing a new head wall flashing. At a minimum, I expect to remove the siding and Styrofoam and install new underlayment, and then seal it with tape around the windows. I also intend to remove the Sheetrock on the inside, remove the insulation to inspect the cavity and remove any mildew that might be present.
I would appreciate your comments and any suggestions to fix these roofing issues. -- via email
A: Thanks for the sketches; they are very helpful.
You mention "added ridge vents." Were there some before and where? Where were the added vents installed?
The cathedral ceiling over the master suite is essentially not ventilated. Counting on airflow from the soffit of this section of roof up through the head wall to reach the ridge vent at the very peak is not realistic. There should have been an exhaust vent at the base of the head wall.
Air Vent Inc. (airvent.com) makes a Utility FilterVent, whose upper leg is installed under the wall's housewrap or felt. You would have to cut the sheathing to create an opening for the air to reach the Utility vent.
The old flashing that was not replaced may be responsible for the recent leaks, but it would not cause leaks at the top of the windows. It is more likely that the heavy rainstorm, if accompanied by a strong wind, caused the leakage over the master suite windows.
Unfortunately, many builders apply housewrap over all wall openings and X-cut it, folding the four flaps over the framing. They install the windows over the housewrap at the top instead of cutting it and inserting the window flange under it. This failure has caused many leaks.
The absence of proper ventilation at the base of the head wall may have encouraged the development of mold. The smell and heat you describe are troublesome, as they may indicate some framing damage.
Your plan to open up the area is sound, and I hope that you do not find any decay. But I do not see the reasoning behind installing wall vents in the regular attic; ventilation from the soffit to the ridge of the long roof should be sufficient.