How to Deal With a Window Inside Your Shower

If you live in an older home in the NYC metro area, Westchester, or Long Island, there’s a good chance your bathroom has a window sitting right inside the shower or bathtub surround. It’s one of the most common complaints I hear as a contractor, and it’s the source of endless frustration — water damage, mold, peeling paint, and drafts that make winter showers miserable.

The good news is you have real options, ranging from a few hundred dollars to a full bathroom remodel. The right fix depends on your budget, the condition of the window and surrounding wall, and whether you’re planning to sell or stay. Let me walk you through every option I’ve installed for clients, with honest costs for our area.

Why Do Older Homes Have Windows in the Shower?

Before exhaust fans and bathroom ventilation codes, a window was the primary way to vent moisture from a bathroom. Builders placed them wherever they fit — and in tight floor plans common in Westchester colonials, Bronx row houses, and Long Island capes, that often meant directly in the shower or tub surround.

The window itself isn’t necessarily the problem. What causes damage is the failed seal between the window frame, the tile or surround, and the wall framing behind it. Water gets behind the trim, rots the framing, and creates the perfect environment for mold. If your window sill feels soft when you press it, or you see black discoloration in the corners, you’re already dealing with moisture infiltration.

Option 1: Glass Block Replacement

This is my most recommended solution for homeowners who want to keep natural light but eliminate the moisture problem entirely. Glass blocks are waterproof, require no maintenance, and provide privacy without curtains or frosted film.

The process involves removing the existing window, reframing the opening if there’s rot, and installing a glass block panel with proper waterproof mortar and sealant. The blocks come in several patterns — clear wavy, frosted, and decorative — so you still get design choices.

Typical Cost

$800 – $1,500 installed for a standard shower window opening. Price varies based on window size, extent of rot repair needed, and block pattern selected. Most jobs complete in one day.

Best for: Homeowners who want a permanent, maintenance-free solution and don’t need the window to open. This is the sweet spot of cost, durability, and aesthetics for most clients.

Drawback: You lose ventilation. If your bathroom doesn’t have an exhaust fan, you’ll want to add one. An exhaust fan installation typically runs $250–$500 and is worth every penny for moisture control.

Option 2: Vinyl Window With Waterproof Surround

If you want to keep a functioning window that opens for ventilation, replacing the old wood-frame window with a vinyl unit and building a proper waterproof surround is the way to go.

The critical detail most contractors miss is the sill. The interior sill must slope back toward the tub or shower so water runs inward instead of pooling against the frame. I use PVC trim and Kerdi waterproof membrane behind the tile to create a completely sealed envelope around the window. The window itself should be vinyl or fiberglass — never wood — with a multi-point locking mechanism that compresses the weatherstrip for a tight seal.

Typical Cost

$1,200 – $2,500 installed depending on window size, extent of surrounding tile work, and whether the framing needs repair. Budget toward the higher end if you’re also retiling the immediate area to match.

Best for: Homeowners who value ventilation and want to keep a traditional window look. Also the right choice in bathrooms without exhaust fans where you need airflow.

Contractor Tip

Ask your contractor specifically how they plan to waterproof the sill. If the answer is “caulk,” that’s a red flag. Caulk is maintenance, not waterproofing. A properly sloped PVC sill with membrane underneath is the correct approach and will last decades without resealing.

Option 3: Block Off the Window Entirely

If the window faces a neighbor’s wall, an alley, or doesn’t contribute meaningful light, closing it off permanently is often the simplest and most cost-effective solution.

The process involves removing the window, framing in the opening with pressure-treated lumber, installing proper vapor barrier and insulation, adding cement board, and then tiling or finishing the surface to match the rest of the shower surround. From inside, it looks like the window was never there.

Typical Cost

$600 – $1,200 installed. This is actually the cheapest option if the exterior doesn’t need extensive finishing. You’ll also need to address the exterior — either matching the siding or installing a decorative panel.

Best for: Bathrooms where the window provides minimal light, faces a wall or tight space, or has extensive rot damage that makes repair impractical.

Option 4: Full Bathroom Remodel With Walk-In Shower

If you’re already frustrated enough to consider major changes, converting the tub/shower combo to a walk-in shower gives you the opportunity to relocate or eliminate the window problem entirely. A walk-in shower can be designed so the window is outside the wet zone, or the shower can be positioned on a different wall altogether.

Typical Cost

$8,000 – $18,000 for a full tub-to-shower conversion with new tile, fixtures, and plumbing in the NYC metro area. This is the premium option but solves the problem completely while transforming the entire bathroom.

Best for: Homeowners planning to stay long-term who want a modern bathroom. Also makes sense if you’re already dealing with multiple bathroom issues — outdated tile, failing plumbing, mold behind walls — where a patch fix doesn’t address the bigger picture.

How to Know Which Option Is Right for You

Start by answering these three questions:

1. What’s the condition of the wall behind the window? Pull back a corner of the trim or caulk and check. If the framing is soft, dark, or crumbling, you’re dealing with rot that needs addressing regardless of which window solution you choose. Extensive rot often pushes the decision toward a more comprehensive repair.

2. Do you need the ventilation? If your bathroom has a working exhaust fan (vented to the exterior, not just into the attic), you don’t need the window to open. Glass block becomes a great option. If there’s no exhaust fan, keeping an operable window or adding a fan should be part of the plan.

3. Are you renovating or patching? If this is the only thing you’re fixing, go with glass block or a vinyl window. If you’re already planning a bathroom refresh — new flooring, vanity, or fixtures — consider rolling the window solution into a broader remodel where the per-item cost is lower because the crew is already mobilized.

What About Temporary Fixes?

I see a lot of DIY advice online about shower curtains over the window, waterproof paint, or adding adhesive film. These are temporary measures that treat the symptom, not the cause. If water is getting behind the frame, a curtain or film doesn’t stop it — it just hides the damage while it gets worse.

If you’re not ready for a permanent fix, the best short-term measure is to remove all old caulk, let the area dry completely, apply a mold-killing primer to any affected areas, and re-caulk with 100% silicone (not latex) caulk. This buys you a year or two, but it’s not a long-term solution.

Frequently Asked Questions

Can I install glass block myself?

Technically yes, but I don’t recommend it for shower installations. The waterproofing details — proper mortar, sealant between the block panel and the shower surround, and rot repair in the existing framing — require experience to get right. A failed DIY glass block installation can leak worse than the original window.

Does replacing a shower window require a permit?

In most NYC metro municipalities, a like-for-like window replacement does not require a permit. However, if you’re changing the opening size, adding framing, or doing electrical work for an exhaust fan, you may need one. I always check local requirements before starting.

Will removing the window affect my home’s value?

A properly executed glass block or window replacement almost always increases value because it eliminates a known problem area. Buyers and inspectors flag shower windows as a moisture risk, so solving it is a selling point. Blocking off a window entirely can slightly reduce value if it meaningfully impacts bathroom light.

How long does the installation take?

Glass block and vinyl window replacements are typically one-day jobs. If there’s significant rot repair needed, it can extend to two days. A full bathroom remodel with shower conversion is typically 2–3 weeks.

Ready to Fix Your Shower Window?

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Or call Gary directly: 347-961-7357