Alcove Tub Installation
Updated February 24, 2026
Swapping out an old alcove tub is one of those jobs that looks harder than it is -- until you hit a snag with the drain or the walls aren't plumb. Most of the work is careful measuring, a solid drain connection, and making sure the tub is level before you lock everything in. We typically see this take a weekend for a DIY homeowner, saving $500-$1,500 in labor if you're comfortable with basic plumbing and a bit of demo work.
Overview
Swapping out an old alcove tub is one of those jobs that looks harder than it is -- until you hit a snag with the drain or the walls aren't plumb. Most of the work is careful measuring, a solid drain connection, and making sure the tub is level before you lock everything in. We typically see this take a weekend for a DIY homeowner, saving $500-$1,500 in labor if you're comfortable with basic plumbing and a bit of demo work.
What to Know
Before You Start
- Measure your alcove opening carefully -- width, depth, and height.
- Standard alcove tubs are 60 inches wide, but some older homes have 54-inch or non-standard openings.
- Check the drain location (left or right) and make sure your replacement matches.
- If you're switching from steel to acrylic, you'll probably need to adjust the drain height since acrylic tubs sit differently.
Removing the Old Tub
- Shut off the water supply and disconnect the drain and overflow.
- Cast iron tubs weigh 300+ pounds -- you'll need a helper or cut it into pieces with a reciprocating saw.
- Cut the drywall above the tub flange about 6 inches up to access the nailing flange.
- For fiberglass or acrylic, you can sometimes cut the old tub apart for easier removal.
Setting the New Tub
- Slide it in and check for level both directions.
- Shim the bottom if needed -- a tub that isn't level won't drain properly.
- Mark the stud locations, secure the nailing flange.
- Don't overtighten screws on acrylic tubs or you'll crack the flange.
Safety Warnings
- Not checking level before securing -- a crooked tub means standing water and a visible gap at the wall.
- Skipping the leak test before closing up walls.
Tools & Materials
- Adjustable wrench and pliers
- Level (2-foot minimum)
- Reciprocating saw (for demo)
- Plumber's putty and silicone caulk
- Drain assembly kit
- Composite shims (not wood -- wood rots)
- Screwdriver and drill
Step by Step
- Shut off water and disconnect plumbing
Turn off the main water supply or dedicated shutoffs. Disconnect supply lines from the faucet valve and remove the drain/overflow assembly. Have towels ready -- there's always leftover water in the trap.
- Remove the old tub
Cut any caulk seal with a utility knife. Remove flange screws. Pull the tub straight out -- takes two people. For cast iron, consider breaking it up with a sledgehammer (wear safety glasses and gloves).
- Prep the alcove
Inspect the subfloor for water damage and replace soft or rotted sections. Check studs for plumb and add blocking if needed. This is the time to update any old galvanized drain pipes to PVC.
- Install the drain assembly
Attach the drain and overflow to the new tub before sliding it into place -- much easier with access. Use plumber's putty under the drain flange, hand-tighten, then snug up with pliers.
- Set and level the tub
Slide the tub in. Check level front-to-back and side-to-side. Shim as needed. Secure the nailing flange to studs with galvanized screws. Connect the drain to the P-trap.
- Test and finish
Turn water back on and fill the tub. Check every connection for leaks. Let water sit 15 minutes and check underneath again. Once leak-free, patch drywall above the flange and caulk the tub-to-wall joint.
Pro Tips
- Fill the tub with water before caulking the wall joint -- the weight settles the tub so the caulk won't crack later.
- Use composite shims, not wood. Wood shims under a tub will rot and the tub shifts.
- Take a photo of existing plumbing before disconnecting anything.
- If the subfloor has bounce, add a mortar bed under the tub for solid, even support.
Mistakes to Avoid
- Not checking level before securing -- a crooked tub means standing water and a visible gap at the wall.
- Skipping the leak test before closing up walls.
- Using wood shims that rot and fail within a few years.
- Overtightening the drain assembly and cracking the tub flange.
When to Call a Pro
If you find extensive subfloor rot, if the drain location needs to move, or if you're dealing with cast iron drain pipes that need cutting -- those are pro territory. Also call a plumber if you're converting from a tub to a shower or changing the valve configuration.
Bottom Line
An alcove tub swap is a solid weekend DIY project. The keys are measuring twice, getting the tub dead level, and testing every connection before closing walls. Budget $200-$500 for materials and save $500-$1,500 in labor.
Frequently Asked Questions
What are expert tips for alcove tub installation?
Fill the tub with water before caulking the wall joint -- the weight settles the tub so the caulk won't crack later. Use composite shims, not wood. Wood shims under a tub will rot and the tub shifts. Take a photo of existing plumbing before disconnecting anything. If the subfloor has bounce, add a mortar bed under the tub for solid, even support.
What mistakes should I avoid with alcove tub installation?
Not checking level before securing -- a crooked tub means standing water and a visible gap at the wall. Skipping the leak test before closing up walls. Using wood shims that rot and fail within a few years. Overtightening the drain assembly and cracking the tub flange.
When should I call a professional for alcove tub installation?
If you find extensive subfloor rot, if the drain location needs to move, or if you're dealing with cast iron drain pipes that need cutting -- those are pro territory. Also call a plumber if you're converting from a tub to a shower or changing the valve configuration.
What is the bottom line on alcove tub installation?
An alcove tub swap is a solid weekend DIY project. The keys are measuring twice, getting the tub dead level, and testing every connection before closing walls. Budget $200-$500 for materials and save $500-$1,500 in labor.
When should I call a professional for alcove tub installation?
If you find extensive subfloor rot, if the drain location needs to move, or if you're dealing with cast iron drain pipes that need cutting -- those are pro territory. Also call a plumber if you're converting from a tub to a shower or changing the valve configuration.
What's the bottom line on alcove tub installation?
An alcove tub swap is a solid weekend DIY project. The keys are measuring twice, getting the tub dead level, and testing every connection before closing walls. Budget $200-$500 for materials and save $500-$1,500 in labor.
How much does alcove tub installation cost?
The typical cost range is $200-$500 DIY / $800-$2,000 pro. Actual costs depend on your location, materials, and whether you hire a professional.
How difficult is alcove tub installation?
This task is rated Intermediate. It requires moderate DIY skill.