How to Lay Mortar Under a Tub

Put on safety glasses, work gloves and a dust mask. Working with cement-based products can result in skin burns from contact with cement after it reacts to water, and you should not breathe the dust either. Mix the mortar outside if possible or in the bathroom with the windows open. Cut the tops off of the bags of mortar mix and pour them into a wheelbarrow.

Add water according to the manufacturer’s instructions. Fill a mixing cup with the appropriate amount of mortar and add it to the wheelbarrow. Shovel the dry mix and the water together and keep shoveling everything around for roughly five minutes or until it forms a thick, creamy mixture of mud.

Lay felt paper and wire onto a wood floor. Concrete floors do not need this layer. Slice the felt paper with a utility knife as needed and lay the pieces where the tub will go. Add a layer of chicken wire on top of that, cutting it to size with wire cutters. Staple both layers to the wood floor with a tack hammer or staple gun.

Shovel the mud into place across the installation area. Empty the entire wheelbarrow into the tub enclosure on top of the paper and wire or concrete slab. Set the tub on top of the mortar or first cover the mortar with plastic sheeting to prevent it from sticking if you want to remodel the bathroom in the future. Fill the bathtub with water and let it sit for a minimum of 72 hours while the mortar cures.