Unsupported fiberglass and acrylic tubs tend to flex under the weight of water plus bathers which can be bad news in terms of your drain staying connected and the tub base remaining solid and free of cracks.
Mortar for bathtub.
Whether you are installing a regular acrylic bathtub that doubles as a shower unit or a larger two person jacuzzi most bathtubs require a mortar base for the tub to rest on.
Thinset is a mortar that is made of portland cement silica sand and moisture retaining agents.
The mortar provides a stable base for the tub to rest on when the tub is full.
The mortar provides a stable base for the tub to rest on when the tub is full so the casing of the tub doesn t have to support all of the weight and crack.
It is applied to the substrate with a notched trowel.
Here s another one of th.
Mix the mortar so that it can support the tub.
Then embed the tub into the mortar.
The mortar conforms to the contours of the tub and when it sets it prevents the tub from moving and supports the weight.
Both regular thinset mortar and floor leveling compound are suitable.
Setting tubs in mortar is a method used by professional plumbers who specialize in quality home construction.
Unless you re installing a cast iron bathtub you are going to need a mortar bed to support your tub base.
It should not be runny but rather stand up on it s own.
The mortar should be evened out and about 2 inches thick on all sides.
Pour the mortar on the subfloor so that it s a few inches from the drain opening.