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Wet Setting vs Glazing Tape for Fixed Windows


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I have seen installations of thermal pane fixed window units that do not have a shash that are installed from the inside against exterior wood stops using both the wet set and glazing tape methods in cases where exterior access is difficult. But doesn't each method require work to be done from the outside? In the wet set method excess caulk needs to be removed from the outside after the caulk sets. In the glazing tape method, the tape replaces the caulk of the wet set, but is it acceptable practice to not also caulk from the exterior? If caulk is used with glazing tape, it can be done as part of the installation and the job finished without returning. With wet setting a return to the job site after the caulk sets up is required, and in addition future replacement of the window can be more problemmatic. But I think there is a temptation for some installers to skip the exterior caulk step when using glazing tape, and given the variabilites at hand the glazing tape itself may not prevent water intrusion especially along the bottom stop. What is acceptable practice?

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Personally, I prefer to see glazing tape plus caulk at the exterior. If you skip the caulk, then a small amount of water always sits in the little crannies around the tape and, over time, causes trouble.

Of course, the stops should be beveled and there should be weep holes as well.

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I always prefer to see a manufactured window product over a site built unit. If you insist on building your own direct sets fab the frame out of cellular vinyl. It will withstand any incidental moisture that accumulates behind the stops.

Unless you are using high performance glass with a high performance spacer there is as much condensation as there is seepage through the glazing media.

Weep holes not only protect the frame assembly, they prevent seal failures. Glazing seals last longer when they are dry. In cold climates surprisingly small quantities of water can leverage seals apart when it expands as it freezes. The glass pack should also be on setting blocks at the quarter points to provide an air gap so the spacer can dry and the weeps can drain.

A skilled glazier can set a glass pack in a single instance with wet or tape media. If there is excessive squeeze out that needs to be cleaned off the glass then it is likely it was set by the same unskilled laborer that smeared the construction adhesive on the floor joists when they framed the place.

It doesn't matter what side it's glazed from, when it is time for replacement someone will have to work on both sides of the unit.

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The best installations combine tape and sealant. A sash doesn't matter, the principles are same. The installation principles are the same. A skilled glazer is absolutely critical to the success of the installation. As Tom states, the system must be designed properly. Executed properly, glazing direct-set in wood frames will last a long time. A skilled glazer has no need to clean up smeared caulk.

I have extensive experience with design, fabrication, installation, repair, and retrofit of such installations across the country. Problems, leaks or seal failures, almost always have a direct correlation with poor installation or the lack of weeps or drainage in the system.

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The best installations combine tape and sealant. A sash doesn't matter, the principles are same. The installation principles are the same. A skilled glazer is absolutely critical to the success of the installation. As Tom states, the system must be designed properly. Executed properly, glazing direct-set in wood frames will last a long time. A skilled glazer has no need to clean up smeared caulk.

I have extensive experience with design, fabrication, installation, repair, and retrofit of such installations across the country. Problems, leaks or seal failures, almost always have a direct correlation with poor installation or the lack of weeps or drainage in the system.

Perhaps you can answer a question of mine about the original post: What is this non-opening window unit that is installed from the inside of the house against exterior wood stops?

Marc

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The best installations combine tape and sealant. A sash doesn't matter, the principles are same. The installation principles are the same. A skilled glazer is absolutely critical to the success of the installation. As Tom states, the system must be designed properly. Executed properly, glazing direct-set in wood frames will last a long time. A skilled glazer has no need to clean up smeared caulk.

I have extensive experience with design, fabrication, installation, repair, and retrofit of such installations across the country. Problems, leaks or seal failures, almost always have a direct correlation with poor installation or the lack of weeps or drainage in the system.

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[Perhaps you can answer a question of mine about the original post: What is this non-opening window unit that is installed from the inside of the house against exterior wood stops?

Marc

I was referring to fixed double pane units installed into rough 2x framing in an old turn of the century house on a hard-to-reach third floor. The double pane units rest on setting blocks that are in contact with the rough framing. The exterior stops are nailed to 1x fascia covering the rough opening on sides and top with the lower stop acting as the window sill and nailed directly to the rough opening. The interior tops are finished hardwood stops of 1x material nailed in the same manner as the exterior stops (sides and tops to 1x fascia and bottom to the rough opening. Hope that helps.

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I was referring to fixed double pane units installed into rough 2x framing in an old turn of the century house on a hard-to-reach third floor. The double pane units rest on setting blocks that are in contact with the rough framing. The exterior stops are nailed to 1x fascia covering the rough opening on sides and top with the lower stop acting as the window sill and nailed directly to the rough opening. The interior tops are finished hardwood stops of 1x material nailed in the same manner as the exterior stops (sides and tops to 1x fascia and bottom to the rough opening. Hope that helps.

It's the stop acting as the sill that will be a problem. Water gets behind the stop and rotts the wood and deteriorates the IGU seal.

If the setting blocks rest on framing, the framing is the sill. The framing /sill needs to slope for water to drain. The glass and setting blocks must be sealed to the sill. The sill stop must weep. Flashing between the sill and stop will aslo help.

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