Install ? - Gypkrete with pex AND electric floor heat in bathroom

DaveL

Questioning how to plan ahead for installation to assure same finished floor levels.

My residential application will use thinset gypkrete w/pex over the framed floor above crawlspace but we want to use electric heat in the bathroom floors.

Floor coverings will be engineered hardwood or tile in main house and tile in bathrooms.

Do I ask for the gypkrete pour to be the same for both main and bathroom areas?

My thinking is the finish height of bathroom thinset for electric cable w/tile will be taller than the engineered hardwood finish height.

You agree? ..... if so so curious of any comments ( ideally install details) of install details to assure they match up.

STEVEusaPA

If you're running pex, why even bother with electric mat? Run all pex, control that bathroom loop off the manifold.
I personally wouldn't use gypcrete. I'd wetbed the bathroom (if using tile), and warmboard or equivalent the areas under the engineered floors.
There only be a slight difference in floor heights easily handled with a threshold.

hot_rod

Ship the gyp in the bathroom.

Gyp is not a good product if water could be present ever. It comes apart like sheetrock when it gets wet. Sealers help, but it it can get wet along the edges.

I'd use a regular "mudset" in the bath area, adjust it to the tile thickness, so it matches the gyp area.

A true tile setter pro will only set tile on a mudset. Plenty of recipes online.

Zman

I would not even consider electric heat mats in a house with a hydronic system. Electric systems are less efficient and have a limited life expectancy.
The only gypcrete failures I have seen were a result of a weak mix. I would not hesitate to install gypcrete in a residential bathroom. I think an electric heat mat would function properly in gypcrete, I just don't see any reason to use it.

hot_rod

Zman said:

I would not even consider electric heat mats in a house with a hydronic system. Electric systems are less efficient and have a limited life expectancy.
The only gypcrete failures I have seen were a result of a weak mix. I would not hesitate to install gypcrete in a residential bathroom. I think an electric heat mat would function properly in gypcrete, I just don't see any reason to use it.

I'll disagree a bit on this one.
I think a small electric is ideal, especially when hydronics are not designed for micro loads and boilers and components cycle to death. Or they allow non condensing boilers to condense on short runs that micro zones enable.
Same with electric towel bars.

This was one of the reason Watts Radiant got into the electric market, it enhanced the hydronic side.

Electric is near 100% efficient

Electric ceiling systems can run for decades, usually until someone drills or nails them.

Tile over Gyp? really, what tile setter would do that? Tile over regular sheetrock around a tub? Who would do that?

I think the original Infloor manual cautioned against gyp in potentially wet locations, toilets do overflow, shower curtain operator error. That white latex sealer added some waterproofing, not enough for submerged gyp.

Zman

All good points, nothing wrong with different opinions.
Electric is 100% efficient at point of use. It is more like 35% efficient if you include plant and transmission inefficiency.
I think there is a drastic difference in gypcrete quality. I have seen gypcrete that has seen no moisture turn to kitty litter. I have also worked on houses that flooded completely that had perfect gyp, even in the bathrooms.

Gordy

As others stated, Skip the gypcrete in bath area, and do mortar bed with pex, or electric mat. A tiler will be able to make up the difference easily.

The advantage of the small zoned electric mat is in that they can be controlled independently from the rest of the house.

You could use a timer, or thermostat with schedules for bathing times in the morning for example.

I did a water based system which wasn’t a separate zone, and found that so long as tile is neutral temperature it’s not a shock to step on out of the tub, or shower. Low to mid 70’s floor temp. However some find lava to be more desirable to walk on with wet feet.

DaveL

I greatly appreciate the feedback! All makes sense now.

I am using electric to avoid micro loads as HotRod said. And wife like the warm tile even in non space heat times of the year.

Thanks much 👍

hot_rod

TCA Tile Council America states tile over gyp products after an approved membrane is installed either a mat or liquid brush on membranes.

I don't think the Elmers glue type gyp sealer is acceptable?

Zman

This one is easy to work with.
https://www.custombuildingproducts.com/products/surface-preparation/waterproofing-membranes-underlayments/redgard.aspx

hot_rod

Sounds like all the gyp products are now 2000 psi minimum. I don't think the early versions were? Looks like a 2000 psi min for tile applications.

I think there are some even higher psi which can b e a finished surface. Sounds a bit like concrete:)