Paint-on waterproofing membrane, physics, and forethought protect an old window—and allow future maintenance—while sealing a big hole in a wet and windy wall
Bill Robinson was called to fix a wall that has numerous leaks. It is the east wall of a house in New Orleans, LA and there is no roof overhang offering protection.
Bill points out in the video that the east wall is the 'weather' wall, meaning that most of the weather—like hurricane Katrina—come from the east. The wall was remodeled in the past when someone added the second story.
One of the leaks—and the focus of today's project—was an old stained glass window whose caning had become loose over the years. They took the window to a stained glass shop for repairs and Bill rebuilt the frame.
A regular glass window would traditionally be bedded in glazing to seal it into the frame, but because this is a delicate old stained glass window, Bill didn't want to bed it into the frame that way. If it ever had to be removed, it would be destroyed in the process, and Bill doesn't roll like that.
Instead, to protect the window opening from rain, he is adding an extra layer of glazing outside the stained glass. The top and sides of the outer sash will be caulked and the bottom left open for condensation drainage.
Flashing the window into the opening was done using a paint-on waterproofing membrane.
"The big issue here is that there is a big wall here that we can't control—we don't own this wall, and we're only accessing part of the wall.
So the way we address that is we create a panning system around there, in this case we're using Poly Wall, this blue product, and the panning system will prevent any water that is coming down the wall from entering the wall, the pan will push the water to the outside.
And that's, always, the best that we can do."
They do not have the luxury of opening the entire wall to address it as a system, so Bill is systematic in his repairs. The preassembled casing is installed over the paint-on membrane.
This particular project needs to be wrapped up quickly, because Mardi Gras is about an hour off, and the streets are going to start filling up soon, making it difficult to escape!
So Bill has a Mardi Gras weather-resistance tip:
"One of the things that we do when we're runnin' and gunnin'—or when we're late for a Mardi Gras parade—is we use a caulk or a sealant on the end grain rather than painting it with a primer and waiting for the primer to dry. As long as we are closing off the end grain, we are good to go."
The casing is screwed into the wall with trim-head stainless steel screws and fastened into the sill using corrosion resistant pocket screws.
"... which is not my preferred method, but in this case, that's all we've got."
The pocket holes are filled with special plugs which are glued in place with a high-quality exterior wood glue, Titebond III, in this case. Later, the plugs are sanded smooth with an orbital sander, puttied with exterior wood filler, primed, and painted.
To seal the head casing, they begin with a historic drip cap profile that is sloped and overhangs the casings. It also has a drip kerf cut in the underside. Over the drip cap is a copper kickout flashing. The wall leg of the copper flashing is bedded in the paint-on membrane.
Before painting the membrane on the wall, however, they protect the casing. The membrane can get pretty goopy when applying it to a vertical surface.
Copper fasteners are used to nail the copper to the wall. It is important to use copper nails with copper flashing to avoid any corrosion from dissimilar metals. The top of the flashing and the nails are then painted into the wall.
With the window weather tight, they install the final pieces of trim—using the run-and-gun method of end grain protection.
With the stained glass window restored, reinstalled, protected and trimmed out, it should look great for a long, long time.
—Bill Robinson is a remodeler, construction trainer, and consultant specializing in building envelope material selection, details, and installation. He lives and works in New Orleans, LA