As long as the subfloor is sound, cement board (Hardiebacker, e.g.) is fine.

I'd be more sceptical of the hot mop unless it's by a large reputable installer. Too many shortcuts.

See link for proper hot mop installation.

Here is a link that might be useful: Hot mop shower pan

Concrete backer board is not structural; it is an "underlayment" that must be placed on top of a structural plywood or OSB sub-floor.

If you mean a hot mopped coating of asphalt, I have never seen it used inside a house. It went out of favor on the East Coast in the 50's and was replaced originally by soldered copper and then synthetic pans. The asphalt must be properly modified to be flexible enough to work so you need a reputable installer. For such a small area I can't see the advantage of asphalt.

The tile guy placed cement board to cover the hole where plumbers cut out plywood when they moved the drain I don't know about construction procedures I just thought if plywood was cut out it should have been replaced with plywood and not cement board They went ahead & hot mopped over that My concern is was it ok that they used cement board in place of the plywood that was cut out I thought cement board was to be layed on plywood The holes in the picture were covered with cement board is that acceptable is it the proper way or was it suppose to be wood plywood

Cement board is NOT to be used as a sub floor. It is meant to be used on EXISTING sub flooring, because it is not meant to be a weight bearing material. It is used for wet applications, as it is mold resistant, resistant to warping, etc. It can (and should be) used as drywall in any area exposed to humidity and/or water. It should also be used ABOVE the subflooring under a tub/shower. While the holes are small, the risk of depleting structural integrity would be too great (for me). Think years down the road. Those cut out areas will be weakened by years of weight being put on them.

From hardiebacker (they make cement board) website:
For all floors:
â¢
Use minimum 5/8 exterior grade plywood or 23/32 OSB with Exposure 1
classification or better, complying with local building codes and ANSI A108.11.
â¢
Joist spacing not to exceed 24â on center.
â¢
The floor must be engineered not to exceed the L/360 deflection c
riteria (L/720 for
natural stone), including live and dead design loads, for the specific joist spacing used.

@AuroraWA greatly appreciated Exactly what I needed to know Thank you

@Renovator8 @AuroraWA @Trebruchet Thank you I appreciate your help I had no clue and they kept telling me it's fine No sort of wood was placed to cover the holes Only cement board then hot mop over it I'm so upset I'll have to have it torn out and redone I will be reporting them I've had other issues since that post Drain not centered to shower not lined up with shower faucet Was floated and it's flat no kind of sloping toward drain I was told the job would take one week but asking for two in case any thing came up It's been three weeks they have worked 3hrs tearing out tub & built shower bench about 2.5hrs for plumbers 3hrs total used cover holes with cement board because they had no wood and to hot mop 1.5hr to tear out & install vanity base lastly two 8hr days tiling shower & still not completed I'm lost on what I can do I call them every day to get information to find out why they are not here when promised or with questions about quality of work example vanity is missing screws and wobbling Any advice

@kirkhall Yes I'm in California Thank you for the advice about posting

worthy wrote: As long as the subfloor is sound,

Your pic shows no subfloor. It will fail prematurely.

"Cement backer board" is a generic term with no real standards or definition. Therefore not all cement/concrete backer boards are made the same.

HardieBacker 500 Cement Board is labeled as a "cement backer board" but that is misleading because it is a "composite" material made of crystalline silica, portland cement and cellulose fibers, a fact difficult to find on Hardie's website. This board is too sensitive to heat to be used in a steam shower and crystalline silica dust is a carcinogen. There are many better products available this is one to avoid.

The oldest and best "cement tile backer boards" are fiberglass mesh reinforced concrete (portland cement and expanded clay aggregate) and are impervious to moisture and heat.

No backer board should be used to support a floor by itself however since the loading will be very light the success the floor will depend on what was actually used and if any blocking was added.

Is this "contractor" licensed and insured? Do you have a properly executed contract? I certainly hope so or you may be in trouble with getting this resolved shy of paying again to another contractor.

I agree with Renovator8, Depending on what they actually used it could be fine, or not.

SCG

@worthy @Renovator8 @SouthCountryGuy Correct no floor just holes This is what was used to cover holes no wood just same as walls Picture shown I can't thank you all enough for all of your help

beauty_brains:

Apparently your floor installation does not meet Durock manufacturer's instructions:

Limitations

3. âÂÂThe subfloor should be APA Span Rated plywood or OSBâ¦âÂÂ

9. âÂÂDurock cement board is not designed for use as a structural panel.âÂÂ

Your wall installation does not meet the manufacturer's specifications either; the screws are too far apart. Are they drywall screws? Those are not approved.

Here is a link that might be useful: Durock

This post was edited by Trebruchet on Tue, Sep 9, 14 at 7:26

Renovator8:

Hardie 500 is approved by the manufacturer for use in residential steam showers. Relating to this thread, it has more than double the flexural strength than Durock:

Here is a link that might be useful: Hardie