# Ceramic tile over styrofoam



## chrisrosenb (Jan 13, 2012)

I have worked in remodeling for over 35 years & installed a lot of floor tile. I am getting ready to remodel the laundry room/bathroom in the basement of our home. I have an idea that I have never seen done or heard of being done, so here goes.

Our house was built in the early 60s with a walk out basement & electric baseboard heat. A little over half of the basement is finished living area, the rest is unheated garage. The floor of the garage area is at grade, the floor of the living area is about 6" above grade. The foundation walls are block. The concrete slab of the living area extends through the door openings to the garage & to the outside.

In the winter the basement floor would get very cold to the point that if we tracked snow inside on the vinyl flooring, it would take several hours for it to melt. We had heavy carpet & pad in the family room area but it was still to cold for the kid to play on the floor in the winter. 

In 2010 we install an electric heat pump. To install the duct work we had to remove the ceilings & some wall coverings. We decided to redo the floor covering in the entry & family room area at the same time. 

What I did in those areas was to put down 6 mill visqueen, 1" high density styrofoam, floor pad & laminate flooring. I also raised the exterior doors 1 1/2". The combination of the forced air furnace & insulation on the floor has made the room very livable in the winter.

I left the floor in the laundry/bath as it was with vinyl over concrete. 
It is still a very cold room. It is not fun stepping out of the shower onto an ice cold floor. The room is 11" X 11'. 

My idea is to is to thinset hd styrofoam to the concrete, then thinset 1/4" cement board to the styrofoam & then lay the floor tile. To help the the adhesion to the styrofoam, I thought I would make some sawcuts in each side to give the thinse some grip area.

Has anyone done this? Do you think it would hold up?


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## Taurus Flooring (Jun 1, 2006)

If anything, I would use 3/4" exterior plywood over the styrofoam and then an isolation membrane and tile over that. It's important that there is no movement under the tile.
The other way you could approach it is by using a heating pad over the concrete floor with tile (I'd also use a isolation membrane here) over it.


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## rusty baker (Jun 14, 2008)

No and no.


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## angus242 (Oct 20, 2007)

Instead of going all rogue with a non-mechanically attached method, why not just add electric heat to the floor and do a proper tile installation?


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## KnottyWoodwork (May 23, 2010)

I'm in for a negative on that. But atleast you're experimenting on your own home :thumbsup:


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## bconley (Mar 8, 2009)

use some wedi board


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## jb4211 (Jul 13, 2010)

angus242 said:


> *Instead of going all rogue with a non-mechanically attached method*, why not just add electric heat to the floor and do a proper tile installation?


I was going to say just that, but the way you said it made me spit out my coffee. :laughing::laughing::laughing::laughing:


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## angus242 (Oct 20, 2007)

bconley said:


> use some wedi board


Wedi will insulate but not heat. A very cold slab will still translate into a not-as-cold tiled floor. Dollar to dollar, I'd heat before solely insulating.


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## bconley (Mar 8, 2009)

angus242 said:


> Wedi will insulate but not heat. A very cold slab will still translate into a not-as-cold tiled floor. Dollar to dollar, I'd heat before solely insulating.


True, he didn't say anything about heat I was just trying to make sure he looked at other options before doing what he outlined.
Nu-Heat over the WEDI works great BTW


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## angus242 (Oct 20, 2007)

bconley said:


> True, he didn't say anything about heat I was just trying to make sure he looked at other options before doing what he outlined.
> Nu-Heat over the WEDI works great BTW


Not a bad idea there either. I was waiting for him to ask more questions and going to suggest a cork tile underlayment and then heat over it :thumbup:


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## TNTRenovate (Aug 19, 2010)

Would the Kerdi Board rated for the floor? If it is, is it rated for heat? If so, then couldn't you use that as a setup? Just a thought....


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## angus242 (Oct 20, 2007)

TNTSERVICES said:


> Would the Kerdi Board rated for the floor?


Nope


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## TNTRenovate (Aug 19, 2010)

angus242 said:


> Nope


What about this? I know it's a UK site, but it states how to install it on the floor.

http://www.schluter.co.uk/produkt.aspx?doc=2978.xml&pg=verarbeitung

Use of Schlüter-KERDI-BOARD in floor areas 

To install Schlüter-KERDI-BOARD in 5, 9, 12.5 and 19 mm thicknesses the substrate must be level, ready to bear weight and free of all substances that may weaken the bond. Any levelling must be completed prior to installing Schlüter-KERDI-BOARD.
The adhesive must bond well with the substrate and mechanically set in the anchoring fleece of Schlüter-KERDI-BOARD. Standard dry set mortars as defined by EN 12004 are suitable for most substrates. Otherwise, select another suitable adhesive, carefully checking for any incompatibilities of materials.
Apply thin-bed mortar over the substrate with a notched trowel and fully embed the anchoring fleece of the Schlüter-KERDI-BOARD panels in the adhesive bed. Tightly abut the individual panels and align them appropriately. Observe the curing times of all materials.
To install Schlüter-KERDI-BOARD in thicknesses of 28 mm or more, the substrate must be sufficiently load bearing. Over such substrates, Schlüter-KERDI-BOARD can be installed with dabs of thin-bed mortar or other suitable mortar, followed by height alignment. To ensure proper weight bearing of the covering, place the dabs of mortar closely together. Apply thin-bed mortar to the joints at the edges of the panels and ensure they are supported by dabs of mortar from below.
Use an edge strip to rule out the buildup of tensions in Schlüter-KERDI-BOARD and the tile covering in edge areas.
The tiles (minimum size: 5 x 5 cm) can be installed immediately after fully embedding the Schlüter-KERDI-BOARD panels, using a dry setting mortar that meets the requirements of the covering. If using dabs of mortar, allow them to cure first for full weight bearing of the substrate. Choose a notched trowel to match the tile format. The curing times of the thin-bed mortar must be observed.
Observe the applicable technical standards for movement joints used in field definition and edge and connection joints.


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## angus242 (Oct 20, 2007)

They also use a modified thinset for installing Ditra in the UK.

Try the US site:
http://www.schluterkerdiboard.com/media/KERDI-BOARD-Cutsheet.pdf


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## TNTRenovate (Aug 19, 2010)

angus242 said:


> They also use a modified thinset for installing Ditra in the UK.
> 
> Try the US site:
> http://www.schluterkerdiboard.com/media/KERDI-BOARD-Cutsheet.pdf


I saw that, just thought it curious that they say it's okay in the UK and not in the US.

So the Wedi board can be used on a floor?


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## TheItalian204 (Jun 1, 2011)

Why not to screw plywood down and use ditra+heating system?...

I guess HD polysterene is cheaper :laughing:


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## angus242 (Oct 20, 2007)

TheItalian204 said:


> Why not to screw plywood down and use ditra+heating system?...


Expense. 

Why ply _and_ Ditra?


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## TheItalian204 (Jun 1, 2011)

angus242 said:


> why ply _and_ ditra?


*overkill*


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## angus242 (Oct 20, 2007)

I don't think adding ply over a slab dictates overkill. I'd much rather set tile on a slab instead of over wood. 

If anything, skip the ply. It does nothing but raise floor height.


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## PrecisionFloors (Jan 24, 2006)

Radiant heat - SLC - Nobleseal - tile. If it were mine anyway. Why waste time with cobbling something together when there are proven methods easily available? That's a small room too, so the cost is negligible in the grand scheme of things.


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