Do I shim the front of a fiberglass tub in order to compensate for an
uneven slab ? Shims made out of what ?
Long version -
Replacing an old worn cast iron tub with a new American Standard
Americast fiberglass tub. (Old one was 60 years old, nasty, and of
course cold). This brand of tub does not get a mortar bed under it,
the weight of the tub rests on the stringer and the fron edge of the
The plumbing is real simple, I'm reusing most parts and have no rough
ins to change or anything.
BUT the slab is crooked. The tub is a right hand drain and the floor
slopes down half an inch (left side is half inch higher than the right
side where the drain is).
The back of the tub will rest on the stringer so it will be level no
matter what but the front lip of the tub will be a problem.
Do I use shims ? Made of what ? Plywood ? How many shims, like one
every foot ? I'm concerned about the weight of the tub (and me and
water) resting on that front lip.
Also thought about leveling the floor but I've already done that to
the extent I could, any more leveling to fix the tub area will cause
there to be a half inch step to get into the bathroom. Ans Level Quik
Make a level pad to set the tub on, and fake the front edge with a piece
of scribed trim.(The plastic faux wood trim made from old pop bottles is
great for bathrooms.) Don't need to shim the whole space, just where the
hardpoints are on the bottom. Look at the bottom, and at the digram
usually printed on the box. Just like your car has special spots to
place a jack, a glass tub has pads to catch the weight. Make sure you
don't raise it too high- stepping down from tub to bathroom floor
confuses people and makes them fall. (My sister's house guest suite is
like that- I added a grab bar before I left.)
Yes, shim the front with something plastic, pvc boards if seriously off, if
not too much look at the recycleing marks on some used plastic containers,
try to find ones with the number 2 on them which is High Density
Polyethylene, usually laundry soap containers, #1's would be the second
choice, I.E. soda bottles. The tub should be level on the edge. Most
fiberglass tubs these days have the pitch built in to them, you can verify
on your brand with a level. Also, while it does not get a mortar bed, you
should use plaster as a bed, not the premix drywall compound, use a setting
type plaster. If you don't, you will have a "spoungy" tub. Most
manufacturers also recomend this for rigidity.
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