It’s Cold Outside
If You Replaced Your Windows Three to Five Years Ago – It’s Time for a Quality Check!
Unfortunately, the majority of windows are replaced in a way that leads to slow, insidious damage, a “block frame” methodology.
This approach does not use nailing fins or flashing to form a proper air and water barrier. Instead, a window is slipped into the opening, secured to the house through the window frame, and the only barrier to air and water are, in order, exterior to interior:
- Caulk – the caulk bead will break down in 1 to 3 years depending on the quality used, most quickly with vinyl windows given the high expansion/contraction of vinyl in our semi-arid climate
- Backer Rod – a pre-caulking gap filler that looks like a rope
- Minimally Expansive Foam – Air-tight foam that fills the gaps between the window frame and the wall
Once the caulk breaks down, water makes its way into the wall cavity in liquid and vapor forms. The backer rod will slow the penetration of water and the foam will divert it even as it is slowing being deteriorated. Thus, the wall damage being done is hidden and insidious.
A block frame install is only certified as the right way to install a replacement window in masonry openings. In all other openings, a certified install must include the use of nailing fins to attach the face of the window to the wall and flashing tape to form a water management system around the window and act as the first line of defense against air leakage. These steps, in addition to the block frame methodology outlined above are the right way to install a replacement window and the only way we do it at SolarGlass.
Why do most replacement companies use only the block frame methodology? Profit. It is more than twice as fast to do a block frame install as a certified install. Since the majority of us don’t know the difference, and most replacement company’s subcontractors are paid on a piece rate for each window installed, this corner is routinely cut.
Often times the block frame approach is sold under the guise of saving you money – “we will not disturb your exterior trim so we won’t have to charge you for materials and you won’t have the hassle of repainting!”
In the case of stucco exteriors, doing the install right is substantially more expensive than the block frame approach as it is very difficult to patch stucco to the same appearance as the surrounding wall after the original stucco was cut back to allow for a certified installation.
How to tell which installation methodology was performed? If your window is in brick or stone, it was a block frame install as there is no opportunity to use the nailing fin or flashing. If not, examine the caulk around the windows that receive the greatest sun exposure, usually the west or south elevation. If the caulk is separating from the window, you can insert the blade of a knife or an awl into the gap. If you don’t hit a solid surface, the nailing fin under the flashing, within an inch to an inch and a half, you have a block frame installation.
What can you do about a block frame installation after the fact? It is imperative that the caulk be maintained gap-free. Even if gaps have opened up, re-caulking and subsequent diligent maintenance should minimize any damage and maximize the longevity of the install.