This tub is being replaced with a walk-in shower. What’’s the best thing to do about the stained-glass window? (Robin Pattison)

We are about to remodel our master bath, and we’re wondering what to do with the round stained-glass window over the current tub. We want to remove the tub and have a large shower put in its place. I would love to keep the stained glass. However, as it’s not energy efficient, I would like to have an insulated window put in its place. At your website, I read an article about placing a stained-glass panel in front of an existing window. I was not sure if this could be done in a shower or if the stained-glass window can be removed without damage. What are your thoughts on this issue? What other tips do you have about this big project? — Robin P., Carrollton, Tex.

I’m about to embark on my own bathroom-remodel project, but I don’t have to solve a window problem like you do. My challenge is to fix all the wasted space in my basement bathroom, the result of poor planning by the previous owner of the home and architect who built it. In my case, I’m taping a huge video series about my project and intend to put all of the videos up on my AsktheBuilder YouTube channel so folks like you don’t ever make mistakes in your bathroom projects.

The photo of your current bathroom with the stained-glass window over the tub is stunning! This window is going to provide you with more than one challenge, and you’ve got lots to think about before making your final decision.

I have remodeled many bathrooms with a window in a tub/shower area. In every wood-frame house that had these windows, I discovered that they caused serious problems. Leaks and condensation wreaked havoc inside the walls around and below the windows. The only houses that were immune to such damage were those built of solid masonry — it didn’t seem to matter if water splashed onto the window or condensation dripped down the window seeping into the wall cavity.

If you want to retain the look of the window, here is an easy option. Many tile manufacturers can take a high-resolution photo and put it on a ceramic tile arrangement, much like an image on a jigsaw puzzle.

Doing this could create the illusion of that gorgeous stained-glass window inside your new shower, but it wouldn’t be a real window. You have so much natural light coming in from your overhead skylight that’s immediately adjacent to the shower area that it may fool some into thinking that the image on the tile is real.

If you are determined to keep the window in your new shower, you will need to involve an expert in the project who can create a special leak-proof flashing that will conform to the circular opening. The entire wall will need to have a flashing or a high-performance vapor barrier that will collect and divert any water back to the shower base, where the water will eventually reach the plumbing drain.

Don’t underestimate the complexity of all of this working together. If you make one mistake with one element of the project, you’ll have a leak down the road. It will be very expensive to fix the problem, especially if the defect creates a latent defect, where the damage doesn’t show up for years.

No matter what you decide to do, here are a few tips to help you have a shower that will not leak. First and foremost, understand that you need to control all water, in both liquid and vapor form. You must not allow water vapor into your wall cavity on the exterior wall. Cross-laminated vapor barriers offer, in my opinion, the best protection.

If you have a wood subfloor under your current tub, consider cleaning it well after the demolition and coating it with two or three coats of clear urethane. Do the same with the wall studs. This may seem crazy, but anything you can do to slow or stop water from soaking into the wood in case of a leak will help prevent rot.

Before coating the wood with urethane, I’d spray on two coats of a borate solution and allow that to dry. Borates are great products to prevent wood rot, but they’re water soluble. The urethane will lock the borate into the wood for many years.

Think about water that might get behind the finished wall of your new shower. What can be done to force that water into the shower pan so it ends up in the shower drain? Make your contractor do that. Do not listen to his reply that caulk will stop these pesky leaks. You want a permanent solution that’s hidden behind the walls.

Do whatever is necessary to install an access panel on the other side of the wall where your new shower faucet will be. You want to be able to have full access to your shower valve in the future. Don’t allow the contractor to talk you out of this. Access panels to tub and shower plumbing were standard features in just about every old house I ever worked on, including the one I grew up in.

Read the installation instructions that come with the new shower. If you’re installing one that’s preformed acrylic, be sure the base is supported so it will not flex and “oil-can” as you stand in the shower. This movement will cause cracks and leaks down the road.

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