What Were The Builders Thinking With This Movable Pool Floor?

It started with a phone call from the owner’s personal assistant.  They had movable pool floors in the pool and spa that didn’t operate properly.  They wondered if I’d fly up to Whitefish, MT, and have a look-see at their problems.

A Failing Movable Pool Floor System

Upon my arrival, I was met with an odd home-brew moving floor system. In an attempt to reinvent the wheel, the pool builder attempted to create his own moving floor systems.  The premise was that ballast tanks would be filled with water to lower the floor and be filled with air to raise it. 

In theory, it may have worked, but as with any unproved and untested design, there are always kinks.  Testing theories on a wealthy client and working out the kinks on a multi-million dollar pool project, is never the place to learn.

A Poor Choice of Materials

To begin with, the structure was fabricated out of aluminum.  Anyone who’s spent time around chlorinated swimming pools knows that aluminum rapidly decays in salt or chlorinated water.  The ballast tanks did not have any bulkheads, so the water sloshed from end to end.  This caused the floor to list to one side or end, binding it within the pool walls.  You can imagine a multi-ton structure wedged within the pool walls. The deck of the floors were finished in Ipe, a hard exotic hardwood.  However, after submersion in water, the wood becomes gray, slimy, and slippery.

To make matters worse, the builder failed to recess the incandescent lights and wall fittings.  So the shifting floor structure would sheer off the glass lenses and fittings.  In a futile attempt to keep the multi-ton structure aligned, the builder cut guide tracks into the walls and installed roller wheels.  Again, the forces at play here grossly exceeded the bolt-on wheel assemblies.

A Laundry List of Problems Unfolds

The moving floor in the spa was another disaster.  The mechanism was a scissors lift, driven by a hydraulic ram.  The builder sourced his hydraulic ram from a local tractor supply store.  Over a few quick months, the leaking ram created an oil slick atop the spa.  Needless to say, the cast iron ram began to corrode within the chlorinated water.

Once I began to evaluate the hydraulics, electrical, and moving floor systems, it became apparent that the entire project would require a substantial renovation in order to be safe, functional, and code compliant.

Out With Old Pool Floor & In With The New

I partnered with a local contractor, Shawn Hossack of Panorama Builders.  Together we came up with a plan to remove the dangerous floor system and install a new fully proven and engineered system.  Though we obtained bids from a number of manufacturers, we settled on systems from Hydrofloors – Twinscape Group. Their technical support and proven track record made the client’s choice simple.

The Scope of Work

The interior of the pool & spa was determined to be not completely plumb and true.  The only means to correct these deviations would be to render them with mortar and tile them.  First, the failing Eco-Finish would have to be removed from the walls, the walls roughened, and prepared for waterproofing.

Since winter was approaching, the decision was made to tent the project under a 100-foot by 50-foot tent and pump in 2,000,000 BTU of heated air 24/7.  Over the winter months, the exterior temperature dropped to below -18ºF with the wind chill.  Meanwhile, the interior temperature remained a comfortable 60ºF!  The cost to operate the diesel heat exchanger and blowers averaged $10,000 a month.

To get the exact contours from which Twinscape could begin fabrication, the crews at Panorama tiled the top 3 feet of the pool in order to generate a 3-D model of the interior. 

Since the walls are supposed to be perfectly vertical, these 3 feet would be a representation of the entire pool depth.  From this model, Twinscape was able to begin fabrication, while progress was being made on tiling the pool.

The spa wasn’t quite deep enough to accommodate a properly designed scissors lift.  We remedied this by raising the spa walls 18 inches and replumbing the jets.  Once the concrete had cured, the tiling of the spa began in parallel with the pool.

Additional Observations

The clients chose a beautiful blue tile from Interstyle.  The hydraulics and mechanical systems were corrected to the best possible conditions without demolishing the decking and totally re-piping the pool and spa.  Some pumps were eliminated and their pipes were re-purposed in order to reduce the line velocities on the remaining pumps.  Some drains were converted to returns and unblockable drains and sump were installed. The ineffective skimmers in the catch basin were removed and their suction pipes were connected to the basin floor drains.  Water chemistry management systems were installed to eliminate corrosion of the new floor systems. 

During demolition, we discovered many electrical and bonding deficiencies.  The incandescent lighting was converted to strip lights from Hydrolume and proper j-boxes and conduits were installed. 

To eliminate the fall hazard over the vanishing edge, we partnered with Reynolds Polymers to fabricate and install an acrylic railing system.  The panels were set into a channel within the floor.  So, regardless of the height of the floor within the pool, there will always be a railing of sufficient height to protect pedestrians and bathers.

In Conclusion

All in all, the repairs to the project took almost 20 months.  The ensuing lawsuit resulted in a jury trial and a judgment of $4,750,000 – to date, the nation’s largest judgment in a residential pool construction defect case.