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Structure: The Sunken Tub

Our house had numerous structural problems, many (but not all) of which were the result of bad DIY by the previous owner. This post is part of a series outlining what we did to correct these problems.

The ensuite bathroom had what we originally thought was a pretty cool feature: a large sunken whirlpool tub.

sunken tub
The sunken tub.

To “sink” the bathtub, the previous owner cut out a section of the floor in the shape of the tub. He dropped the joists and flooring down about a foot or two and supported them with a framework of 4x4s and other lumber. Plumbing that would have run in between or along the bottom of the joists had been rerouted and the result was pretty ugly.

platform for sunken tub
The supporting structure for the sunken tub.

There were a lot of problems with the ensuite bathroom that I won’t get into here, but suffice to say that I decided to completely gut it. Now I could restore the structure.

A reciprocating saw made quick work of the tub which I cut it into manageable chunks and moved them outside. In the basement, I removed the supply lines and the drain. The drain was not properly vented anyway.

Removing the support structure in the basement.

Undoing the previous owner’s handiwork

With the tub and the plumbing gone, I could get rid of the lowered floor joists and flooring that had supported the tub while leaving the framing structure in place to support the rest of the floor.

In the bathroom, I got rid of the tiled skirting for the tub, leaving a shortcut to the basement.

shortcut to the basement
Watch that first step!

Replacing structure

In the basement, new 2×10 joists were sistered to the original floor joists using carriage bolts. Where we had to cut one of the joists so we could work it into place, we reinforced it with a repair plate.  

sistered joists
Sistered joists

I did this work in 2006. Because of how the original floor had been cut off along the rim joist, I was unsure of how to best add structural support for the new floor. So I left it for the pros. The contractors we hired in 2009 for the major renovation completed the repair. To support the edge of the floor, they fastened wood blocks to the end joist carry the load to the sill plate and added another joist between the blocks. The repair was not as complicated as I thought it would be. Turns out, I could have done it myself.

Added support for the plywood floor.

Structural Repairs: How to “unbutcher” a house

The Back Dormer: Repairing water damage and fixing framing problems
The Back Dormer:  Adding ventilation and eliminating water leaks
The Sunken Tub
Supporting a house from the basement up
Load-bearing walls


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