Planning a Bathroom Remodel? What to Check Before You Pick a New Shower

Picking out tile, a glass enclosure, or a new tub is the fun part of a bathroom remodel, and it's also the part most homeowners focus on first. But the plumbing underneath and behind the new fixture is what actually determines whether the finished project performs well for years or starts causing problems within the first year or two.

Check What's Actually Behind the Wall

Before committing to a specific shower or tub configuration, it's worth knowing what supply lines and drain plumbing you're working with. A home with original 1950s or 1960s plumbing behind the bathroom wall is a very different starting point than one that's already been updated, and that difference affects both the cost and scope of the project.

If your home hasn't had its bathroom plumbing touched since it was built, opening the wall for a shower installation is a natural opportunity to also address aging supply lines and shutoff valves while everything is already exposed, rather than treating it as a separate project down the road.

Waterproofing Matters More Than the Visible Finish

A beautiful tile job or glass enclosure means very little if the waterproofing membrane behind it fails. This is the layer most homeowners never see and rarely think about, but it's the single biggest factor in whether a new shower develops hidden water damage within its first few years. A rushed or improperly installed membrane is one of the most common reasons a shower that looks perfect on the surface starts showing problems in the surrounding drywall well before it should.

Drain Placement and Slope

A shower pan needs to slope correctly toward the drain, typically a small but precise grade across the entire floor, so water doesn't pool anywhere. Getting this wrong is subtle enough that it's not always obvious immediately, but it shows up over time as standing water, mildew in low spots, or a floor that never quite feels dry. This is a detail worth confirming is being done correctly, not just assumed.

Tub-to-Shower Conversions Need Extra Planning

If you're converting an existing tub into a walk-in shower, the drain location often needs to move, since tub drains and shower drains aren't always positioned the same way. This adds plumbing work beyond a straightforward like-for-like replacement, and it's worth understanding upfront rather than discovering partway through the project.

What a Proper Installation Actually Involves

A well-done shower or tub installation starts with assessing the existing plumbing, not just measuring for the new fixture. That includes checking supply line condition, confirming drain placement and slope, and planning waterproofing before any tile or surround goes in. Skipping straight to the visible finish work is exactly how hidden problems end up baked into an otherwise good-looking remodel.

If your remodel also includes updating the sink and faucet, that's worth coordinating at the same time, since faucet and fixture work often shares the same shutoff valves and supply lines being addressed for the shower itself.

This kind of full-plumbing-first approach matters just as much in Compton's older housing stock, where original bathroom plumbing is just as common as it is in Carson's own postwar neighborhoods.

Questions to Ask Before You Start

• What condition are the existing supply lines and shutoff valves in?
• Will the drain location need to change, and if so, what does that involve?
• What waterproofing method will be used behind the tile or surround?
• Is this a good opportunity to address any other aging plumbing while the wall is already open?

Getting clear answers to these before choosing finishes means the visible part of your remodel is built on plumbing that will actually support it long-term.

Ventilation Is Easy to Overlook

A bathroom remodel focused on the shower or tub sometimes leaves ventilation as an afterthought, but proper exhaust fan sizing and placement matters just as much as waterproofing for preventing long-term moisture problems. A fan that's undersized for the room, or vented incorrectly into an attic space rather than outside, can trap humidity in ways that slowly damage the very finishes you just installed. This is worth addressing as part of the same project, not as a separate concern tackled later.

Timeline Expectations

A straightforward like-for-like shower or tub replacement, same footprint, same drain location, typically takes one to two days once demolition starts. A tub-to-shower conversion or any project involving moved plumbing generally takes longer, often three to five days depending on the scope of tile or surround work involved. Knowing this upfront helps set realistic expectations, especially if the bathroom being remodeled is your home's only full bathroom, since that affects how you'll manage during the project itself.

It's also worth asking early whether the project requires a permit, since plumbing work involving moved drain lines typically does in most jurisdictions, and building that into your timeline avoids a surprise delay partway through.

Getting Multiple Opinions on Scope

For a project involving moved drains or significant plumbing changes, it's reasonable to get more than one assessment of what the job actually requires before committing. Two contractors looking at the same bathroom can sometimes propose meaningfully different approaches, and understanding why they differ, not just which quote is cheaper, helps you make a more informed decision about which plan actually fits your home and your goals for the remodel.

Budgeting for What's Behind the Wall

It's worth setting aside some contingency in your budget specifically for plumbing surprises, since a wall that's been closed for 50 or 60 years sometimes reveals a condition nobody could have predicted from the outside. This isn't meant to alarm anyone into overspending, but a remodel budget with zero room for an unexpected finding behind an old wall is a budget that's more likely to cause stress partway through the project than one that's planned with a reasonable cushion from the start.