Kohler Proflex AirTub Possible - Subfloor/mortar prep?

tub4me · 10-01-2008, 11:39 AM

Thinking about installing a Kohler ProFlex Airtub...
My current tub has the subfloor (2nd floor bathroom) totally cut out between two joists where the drain is located for the entire length of the 5' alcove tub (with no insulation such that I can look down to the garage ceiling on the first floor).
How do I fix this? Insulate and do what to the subfloor?
Plumbing runs below the subfloor height.
What are my options to fix this right with the same kind of Kohler Proflex airtub replacement? Thanks in advance, Jeff.

RippySkippy · 10-01-2008, 12:37 PM

Is the new drain in the same joist bay? If it is, insulate the joist cavity with fiberglass, sister a 2x2 or 2x4 what ever you have handy to the joist and glue and screw a matching piece of sub-floor to them. It should be a pretty easy fix. What's your location, does it get cold enough to freeze the trap an drain line? Is the garage heated?

tub4me · 10-01-2008, 02:02 PM

My garage is not heated but as it appears it is attached to the house.
I have opened up the back of the shower wall (with the plumbing) from the walk-in closet behind the shower. This is how I know the underneath is open. In the winter, the cold air just streams through that opening into the closet (I could dress a dead deer in that closet if my wife wouldn't get so upset). It has not frozen up so far as I am guessing that the heated walk-in closet with the opening might mitigate the cold to a degree.

I would hate to have a problem with that after using the mortar on top of the patched subfloor, but I should not need to get to anything that is not reachable from the closet through the open studs to the remaining opening near the trap.

Also, would the sistered joist be a problem weight wise with 80lbs/sq foot rating required by Kohler for the 60 gallons of water expected in the soaking tub plus the mortar? That was my main concern with such a repair....

Thanks, Jeff.

RippySkippy · 10-01-2008, 03:03 PM

I didn't ask...just assumed, your joist are they full wood or "I" type? If they are full wood, I wouldn't think it would be a problem mainly because with the mortar bed, use full 2x4s glued and screwed. With either full wood or "I" joist , you could always cut the sub-floor out to the center of the joist and put a new piece in with or with out the sisters. I would do the same in my house. The weight is being spread out to the footprint of the mortar bed. I believe the mortar bed is optional (at least it was on my air tub) so if that were the case the entire weight sits on top of 5 4x4 blocks glassed to the bottom of the tub.

As for the coldness...insulate the heck out of things and seal any air hole going between the garage and house.