Im going to put Nu Heat floor mat down on an uninsulated Cement Slab. Should i put down a insulated layer over the cement before i put the mat down? And if so what product should i use for this purpose?

Unfortunately there isn't anything you can put over the slab.

A better choice is the wire cable systems from companys like Easy Heat and Flextherm. Their cable systems (by way of layout)can be configured for unheated slabs.

Ive been told about a product called Wedi-board that your suppose to be able to glue to the slab and then put your heat mat on that has anyone heard of or used it?

I haven't used it yet. Its got a different name I believe in North America. Can't remember what its called.

Woops..I guess its got the same name now.

http://www.wedi.de/home_usa/

Our local supplier here just started carrying the product, so I don't have any feedback other than it's really expensive.

As far as I can tell from the product info it will do what you want.

Yes,it's definitely better to use something like Wedi panel under the NuHeat but it's not a hard and fast rule.I've installed a few NuHeat systems directly on uninsulated slabs.The heat will still radiate into the tile consistently,just not as much as when an insulating panel is used.

hi
when installing a radiant system over an uninsulated slab your operational costs go up but it will still heat.Flextherm and easy heat9installed at 1 1/2" then 3" or flextherm at 2" over an insulated slab will be all the heat you need in the room.Custom just introduced easy mat - a antifracture/acoustic mat that also has an r value to insulate slabs.wire over mat then cover then tile- always be careful not to cut the cables when floating over.
have fun

I ended up using the wedi-board instead of cement backer-board for my shower, as i learned from the rep that it is waterproof, boy what a dream to work with compared to cement board. THis is definitely the product of the future for bathroom stalls, it is twice the price of Cement board but definitely worth it.

FWIW I used WEDI on some second floor showers a few years ago. WEDI is a great product. I bought a full pallet of it and by the time I paid shipping the sheets cost me about $21 per for 3X5's, double what Hardi costs.

I too thought WEDI would take the world by storm but the truth is I couldn't get anyone around here to give it a second look after they heard what it cost. I love the stuff and it is the only true 100% waterproof tilebacker on the market that I'm aware of. I was able to carry eight sheets at a time up the steps of this house, try doing that with cement board.

WEDI easily cuts and trims with a utility knife and you can place it on the wall and nail it with no effort.

If the cost were somehow competitive it would fly much easier.

I'm not at all in favor of placing any cement board on a concrete floor, it just presents too many new problems but in the case of WEDI I would try it. Especially as a thermal barrier under a heat system.

Hello. I put a New Heat matt in my bthroom concrete floor that is un-insualted. It's brand new and I'm having trouble stoking it up to warm tempertures. I set it forr 100 and the warmest i could get was 77..-79. Could it be posible there is not enough power for the unit? I haven't talked to my electrician yet but I need some good acvice from here so I can ask questions. Can you get different breakers for more power?

You will never get the so called max temperature from any electric floor heat system due to heat loss and substate thermal resistance.
There's nothing you can do to the electrical system to cause any changes to the final radiant temperatures. DO NOT mess with the existing set up!

BTW industry acceptable floor temperatures for radiant heat are 66 to 84 degrees.

Nu-Heat is a tile warmer, not a full radiant heat type system. Your temperatures are well with in acceptable specs.

Tiled the Nu heat floor. She now comes up to 83 degree's so I'm happy with that in Canada. Feels good under foot. Thanks guys for the Input.

I have looked into several electric heating companies including Nu-Heat. Is this the most popular and successful design. This felt type mat which holds the wire, requires essentially 2 layers of thinset, one under and the other overtop of the mat. Does this result in an overly thick thinset between the subfloor and the tile? I have prepared my sub floor with a plywood base topped with 1/2" cementboard.

Hello Shower Guy. With the Mat it does not require an overly thick thinset. My mat over the unheated slab is working just fine.

Wedi is a great product I can tell, I use it in the past, today I got new product called Ez-BakerBoard abut 2lb per sheet 3x 5 and today price is abut what was the wedi price in 2006

You right people still get scare by the price, I don’t see it used or sold near the hardi backer or other cement boards, but it dose take some share of the market, and it getting slowly and surely in to the market.

I believe the price will be drop when the manufactures see the potential of selling more for less profit.

I just checked out the Ez-Backer board manufacturers website, and it looks like a good product. There are actually several of these types of products out there, and in testing have outperformed all other products used to thermally isolate a slab from a radiant system. So, now we have Wedi, Bonsal Pro-Panel, and Custom Building Products Easy-Board, and now (Thanks Motti!) EZ Backer Board! Awesome!
I would like anyones feedback on using this product! Thanks!

I finally found some EZ Board for sale at Dal-Tile. It's about $14-$15 a sheet, so about 50% more than Hardi. For a small job, I guess the difference in price wouldn't be much, but for a big floor, most people aren't going to pay for it.

The saving is much greater when the job spec called for waterproofing, then you only need to waterproof the board joint.

I don’t see this product sold as much as standard cement board or hardi baker, but it dose take his share of the market and it dose increase his percents of the market, a big fact is the price drop a bit from last year, and the hardi baker price got up.

Another big factor, is the delivery cost of this product is much cheaper as a pallet weight only about 80 LBS ( not include the pallet) while hardi baker weight about 440 lbs,

Important note: I never look in to if this product safe to use with floor heating, first thought, I don’t think it is, but I sure will check on it soon.

Showerguy

If what you have looked require floating the mat in cement, just go for the SunTouch, with SunTouch mat or the WarmWire spool you install the tile as you cover the mat with thinset, one step installation.

I'm also about to put in a radiant system over an un-insulated slab. I don't think I've gotten a clear picture about what is the best route to take, and the best product to use. Some more questions... for those up to the challenge!

1) What company's system (Nu Heat, Sun Touch, True Comfort [only in Canada?], Easy Heat, etc) is most suitable for this un-insulated concrete slab? Perhaps they all would lose heat equally down into the slab below?

2) If you use a cable system, I assume you end up with a thicker mortar bed to conceal it vs. a thin mat system, thus raising the overall finished height of the tile. Correct?

3) I belive NuHeat is put onto a very think layer of mortar, then a layer of mortar is spread over it for the tile. Cable systems (ie. True Comfort) need to be encased in a thicker layer of mortar, before another coat for the tile bed. The cable route seems a little cheaper out of the box, but are you spending way more $ on extra mortar to make it work?

Thanks very much (in advance!)

1) I personally prefer to use the cable system from Warm Tiles (Easy heat). They have a layout pattern for uninsulated slabs.

2) You don't need a thicker bed over a wire system. A skim coat that just covers the wire is all thats needed.

3)I find the cable system less expensive and more forgiving in odd room shapes. The extra cost for the thinset skim coat and any height issues is negligible.

Great. Thanks very much!

1. I like NuHeat. If heat lose exists for whatever reason ... it effects all the same.

2. After the cable is installed I use 2 or more coats of medium bed mortar to level. I keep my mix as suggested by the manufacturer.

3. No ... level as required and let set. Install your tile when you're satisfied you have a level surface and protected cables.
Yes ... mortar does cost money, but the freedom to install the cables as you wish is a good bonus.
Otherwise ... use the mats.

Thanks again. I actually wrote "think" instead of "thin" in my 3rd question. Whoops. I'm sure you all got the idea.

I have a 1929 house. The basement slab is likely well past the point of cracking. That being said, would you guys recommend putting a Ditra board underneath, or would you slap the NuHeat directly onto the slab?

Ditra gives you that extra insurance.
You will have to skim coat over the Nu Heat if you plan on using Ditra. Ditra needs to be installed over a very flat substrate.

IMO ditra is good for problem situations. A well cured slab is not a problem situation if there are no unstable cracks.

Check the slab carefully and if you have any cracks bigger than 1/16th or cracks with vertical displacement on one side then you should be thinking about some sort of antifracture membrane.

Harry, so the order would be: skim mortar, NuHeat, another mortar layer or 2, then Ditra?

That's a lot of material for the heat of the NuHeat to work up through, isn't it?

Would the NuHeat mesh not act as a poor man's slip sheet if the slab below moves or cracks? In other words, would cracking be mitigated by the fact that the tile would be on a separation sheet (NuHeat) and not directly on the slab?

No skim coat ... just completely install your heating cables THEN apply mortar.
It's very important to make sure the cables are secured well and tight enough so they aren't flopping around.
Nuheat mesh?? Are you talking about cables or mat? I'm unfamiliar with NuHeat mesh.
NuHeat mats are not isolation membranes or slip-sheets. A slip-sheet should have an actual mortar-bed (1-1/4" thick deck-mud) built over top in order for it to succeed.

Install the cable and then embed into mortar so that it becomes part of the slab. THEN intall your isolation membrane over top and then your tile.
Someone else may offer other advice ... this is how I do it.

best stuff like the fellow mentioned earlier and the easiest is easy mat from costum you have to mortared down just like you do ditra and then wires on top works well

Bri, tell us what you think about Easy Mat from Custom!

I can't give you an opinion of the "mortar down" version of Easy Mat.....but the Peal and Stick version is absolute rubbish. I have heard the mortar version works pretty good.

Installing Nu Heat on Cement Slab will ensure that your floor will require less energy to reach the desired temperature. I can suggest you one product that is SunTouch Electric Radiant Floor Heating.

I'm going to be installing Nuheat cable on a concrete subfloor. Any thoughts on using subfloor adhesive (PL, Titebond) to attach the cable guides to the floor rather than hot glue? I'd rather not buy/rent a hot glue gun for this one job and then have to figure out how to use it. I called the Nuheat support line and they said their only concern is how the heat will affect the adhesive but heat isn't applied until everything is buried in mortar.

Thanks,
Yeg

I don't see why PL wouldn't work to hold the cable Guides down, it could just be a little messy and you may need to wait for it to set before you could run your cable. The big advantage to using the hot glue is that it is easy and it bonds right away. I wouldn't rent a hot glue gun, you can buy one for $20.00 at the hardware store or Wal Mart - just a regular old hot glue gun like your mother used to use to glue beads to a styrofoam ball. The hot glue isn't meant to permanently hold the guides to the floor. The guides aren't supposed to hold the cable to the floor permanently. The hot glue and cable guides are just there to hold the cable in place until you get the cable covered with cement.

Here's a tip - use the hot glue to hold the cable to the floor in a few places over the span between the cable guides. The cable will have a tendency to float when you pour your self-leveler. Use a small bead of hot glue to keep it from floating. And don't try using thin-set t level the floor unless you're extremely good with a trowel - it's sticky and difficult to get smooth. Use self leveling cement.

Thanks J&D

Nuheat specifically says to use "industrial grade" hot glue. I tried my dad's hobby hot glue gun on some concrete and it did not stick at all. That's why I started considering options. Perhaps there is a different type of hobby glue that does work on concrete. But if PL works I will stick with that (sorry).

Thanks for the tip about gluing the cable mid-span. A professional installer will take over once I get the cable in place and it is my understanding that they will use mortar rather than SLC to cover the cable. My maximum span between guides will be 3 feet.

Yeg

I didn't mean to suggest using the came sort of glue as you may have used for crafts, just that the same gun will work for the grade of glue that you would use for this project. Sorry for the confusion.

Best of luck. I'm sure you'll do a great job and you'll love having toasty warm feet when it's all done!

If your talking about PL Premium adhesive, there's no way that will work. It takes 24 hrs to dry and does not have the ability to do instant grab or bond.

Hot glue works the best. Concrete needs to be really clean and free of dust for even hot glue to work.

An alternative to PL might be Loctite Powergrab. It's available at Lowe's, maybe HD as well. I don't have any experience using it on heat cables, but I've used it for a lot of other things and it works great.

http://www.lowes.com/pd_205801-133-1290020_0_?productId=3020319&Ntt=powergrab&Ntk=i_products&pl=1&currentURL=/pl__0__s?newSearch=true$Ntt=powergrab$y=0$x=0&spellCorrectedTerm=

Thanks for your response, Randall. Now you've got me worried about using PL. Why is the fact that it takes 24 hours to dry a problem? As for hot glue, is there a particular type that you recommend? As I mentioned before, I tried the stuff that was in my dad's hobby glue gun and it didn't stick worth a darn to concrete.

Thanks for the tip about Powergrab, Kman.

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Yeg

I guess our perspective (as contractors) would be to have the cables installed and ready to be embedded and leveled with mortar or slc. Something you would be unable to do until the PL took grab.
But ... if you have the time to wait, then by all means use PL or whatever else you'd like to use. Bottom line is to have the cables stable when applying mortar. So ... whatever works.

Thanks Harry,

I got thinking about that after my last post. Who cares if it takes a while to set up? But a contractor does care. He wants to set the guides, lay the cable and get it covered in one trip to the site so I now understand that perspective.

Here's a tip for planning the cable layout - Google SketchUp. My contractor and I used it to design my house but you can use it to design just about anything. Make the cable guide as a component and you can easily duplicate it. Draw the cable as a series of lines connected by semicircles and "entity info" will give you the exact length of cable you need. For those not familiar with SketchUp, it's a free download from Google. There are online tutorials and various "Dummies" books to get you started.

And thanks for this great site!
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Yeg

Canadian Tire has the glue sticks you want. Usually, the heavy duty glue sticks are yellow or amber in colour. The clear is usually light duty, and the white is medium duty.

Thanks Brian,

I hadn't thought of Canadian Tire but I will check them out. I'll still use PL to fasten the guides but will use hot glue to spot fasten the cable mid-span and for the joint between the hot and cold leads.
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Yeg

Thanks to advice from this forum, I got my Nuheat cable installed without a hitch. I glued the guides with Titebond Construction Adhesive, then laid the cable the next day using contractor-grade hot glue from Canadian Tire (thanks Brian). I did use hot glue for a 4" piece of cable guide at the end of the cable and that worked well, so if I ever do this again I'll try setting all of the guides with hot glue.

I've posted 3 photos in the gallery.

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Yeg