Go Back  DoItYourself.com Community Forums > Interior Flooring, Floor Coverings and Coatings Center > Wall and Flooring Indoor Tiling
Reload this Page >

Installing heated flooring over shiplap subfloor, under porcelain tile

Installing heated flooring over shiplap subfloor, under porcelain tile

Reply

  #1  
Old 01-11-13, 11:17 AM
J
Member
Thread Starter
Join Date: May 2009
Location: Canada
Posts: 94
Received 0 Votes on 0 Posts
Installing heated flooring over shiplap subfloor, under porcelain tile

Hi there

Just wondering what the best method of install would be for running the loose wire heated cables over a subfloor that has some sizable gaps in it, and then putting porcelain on top. Should I use a Ditra type product?

Thanks in advance for your help.
 
Sponsored Links
  #2  
Old 01-11-13, 11:27 AM
S
Group Moderator
Join Date: Oct 2004
Location: WI/MN
Posts: 19,571
Received 94 Votes on 83 Posts
OK, let's start at the beginning here - what is your subfloor and what is the size, spacing and unsupported span of your floor joists?
 
  #3  
Old 01-12-13, 12:27 AM
J
Member
Thread Starter
Join Date: May 2009
Location: Canada
Posts: 94
Received 0 Votes on 0 Posts
OK, the subfloor is wood, loosely spaced, 1" thick. Here's a pic. https://www.dropbox.com/s/csgvl325zl...2002.22.19.jpg

The joints are 7" wide, and span just under 8'. They are 16" apart.
 
  #4  
Old 01-14-13, 05:57 PM
H
Member
Join Date: Jan 2006
Location: USA
Posts: 3,524
Received 6 Votes on 6 Posts
The joints are 7" wide, and span just under 8'. They are 16" apart.
I assume that you mean joists, not joints, and that they are likely 7 1/4" which would make them 2x8's, yes? if they are spaced 16" on center and the unsupported span of the joist is 8' then your floor joists are fine for a ceramic/porcelain tile installation. So there is no misunderstanding, the unsupported span is the distance between supports from below at each end of the floor joists.

You cannot install tile over that plank subfloor without adding a layer of plywood over them. Install minimum 5/8" exterior glue bc plywood over what you have. then install the cables, and bury them in 1/2" of portland cement based self leveling compound. You need to install plastic lathe and prime the plywood with the manufacturers latex primer before you pour the slc.
 
  #5  
Old 01-15-13, 11:27 AM
J
Member
Thread Starter
Join Date: May 2009
Location: Canada
Posts: 94
Received 0 Votes on 0 Posts
Right, joists. I imagine they could be 2 x 8's yes. The measurement was around 7". And yes, we're clear on the unsupported span.

I've looked into it a bit more and I'm thinking cork might be better than plywood, cause it'll insulate better, what do you think? Also, is it a good idea to use a Ditra product or does self leveling compound do just as well?
 
  #6  
Old 01-15-13, 11:32 AM
S
Group Moderator
Join Date: Oct 2004
Location: WI/MN
Posts: 19,571
Received 94 Votes on 83 Posts
Wait for the pros to respond but I'd be willing to bet a lot of money you can't put cork under tile.
 
  #7  
Old 01-15-13, 06:28 PM
czizzi's Avatar
Member
Join Date: Jul 2007
Location: USA
Posts: 7,388
Received 14 Votes on 12 Posts
Sigh,....Cork? really? forget about insulation qualities, you are heating the floor and it does not need insulation. What it does need is a proper subfloor with which to prepare for your tile installation. Follow Johnny's guidelines, he is correct.
 
  #8  
Old 01-15-13, 07:00 PM
J
Member
Thread Starter
Join Date: May 2009
Location: Canada
Posts: 94
Received 0 Votes on 0 Posts
Ok, so cork sucks? I was going off a website that talked about the importance of insulating underneath a heated floor. Is that only when you're on top of a concrete slab or something? I have the basement underneath
 
  #9  
Old 01-15-13, 08:36 PM
sam floor's Avatar
Forum Topic Moderator
Join Date: May 2010
Location: floor installer
Posts: 964
Received 15 Votes on 11 Posts
The cork would have too much give to it. You do realize that the type of heat you are installing is not intended to heat a room but just to warm the floor?
 
  #10  
Old 01-15-13, 08:58 PM
J
Member
Thread Starter
Join Date: May 2009
Location: Canada
Posts: 94
Received 0 Votes on 0 Posts
Yeah, I hear some people say that but I've never heard the rationale, besides which, entire houses are actually heated with radiant floor heat. Plenty of people have told me I can use it as a primary source of heat, but I'm thinking then it should be insulated underneath. I'm doing a kitchen reno in which there's no space for another heat source, so I do need it as primary.
 

Last edited by jpenns; 01-15-13 at 09:18 PM.
  #11  
Old 01-15-13, 09:09 PM
J
Member
Thread Starter
Join Date: May 2009
Location: Canada
Posts: 94
Received 0 Votes on 0 Posts
What about something like this? Warmup | Insulation Boards | Floor Insulation Boards

Or I guess I could just use plywood and insulate underneath the subfloor in the basement?
 
  #12  
Old 01-16-13, 04:06 AM
sam floor's Avatar
Forum Topic Moderator
Join Date: May 2010
Location: floor installer
Posts: 964
Received 15 Votes on 11 Posts
The underfloor heat used for heating a living space is usually hot water heat. Not electric heating mats. In cold weather, you will be disappointed with the results.
 
  #13  
Old 01-16-13, 07:32 AM
J
Member
Thread Starter
Join Date: May 2009
Location: Canada
Posts: 94
Received 0 Votes on 0 Posts
Yeah I've heard that too, but because why? I've looked into hydronic here cause I do have a hot water boiler system with radiators as my primary for the house. I've been told you get about 30 BTU per sq ft with hot water radiant. I've got a 90 sq ft floor plan, so that gives me 2700 BTU, whereas if I put in a 1350 W cable I'm getting 4600 BTU.
 
  #14  
Old 01-16-13, 08:22 AM
H
Member
Join Date: Jan 2006
Location: USA
Posts: 3,524
Received 6 Votes on 6 Posts
What Sam said. The electric heating cables and mats are meant to make the floor warm to stand on, but are not meant to be a primary heat source. Typically the hydronic systems are used if you want it to be a primary heat source. Your best bet is to check with the manufacturer of your cable system.
 
  #15  
Old 01-16-13, 11:09 AM
J
Member
Thread Starter
Join Date: May 2009
Location: Canada
Posts: 94
Received 0 Votes on 0 Posts
Sorry I need to hear a reason why. The type of heating is determined by heating power and efficiency. So I understand that when doing radiant as a primary source for a whole house, hydronic would be the choice, for efficiency. But for one room that's not as crucial, and I can get more BTU out of electrical than hydronic. So, once again, why will I be dissatisfied with electrical?

All the cable manufacturers say they can be used as a primary source
 
  #16  
Old 01-19-13, 11:13 AM
Tileguybob's Avatar
Member
Join Date: Dec 2004
Location: Ocean Grove, NJ
Posts: 931
Received 0 Votes on 0 Posts
Some rooms can be heated with the electric wire but there are a lot of loopholes and caveats. In the sort form, an interior room would be ok but a sunroom or a room with a lot of glass, not so much. Insulating the underside of the floor joists will help redirect the heat upward and into the tile. As Johnny said, you will need to make the subfloor stable and suitable for tile by putting in the plywood. Ditra would go over the floor warming wires and just under the tile. the Ditra will help distribute the heat more evenly and reduce areas of warm and cool. The electric free form wire, if used should be spaced about 3 to 4 inches apart, the mats are already prespaced.
My kitchen has the free form wire. I installed it over a plywood subfloor and encapsulated it in self leveling cement. Then I put the Ditra down and tiled over that. It takes an hour or so for the tile to feel warm but I was able to remove some of my old baseboard heat and gain more space for cabinets. Yes, it raised the height of the floor but I had an oak reducer put in that matches the hardwood flooring. If you feel that height is an issue then do something else, dont use tile. its an either/or proposition. Tile has to have that stability under it that vinyl, wood and carpet dont.
 
  #17  
Old 02-14-13, 08:45 AM
J
Member
Thread Starter
Join Date: May 2009
Location: Canada
Posts: 94
Received 0 Votes on 0 Posts
Thanks tileguy, I just saw your post now. Where did you get the oak reducer? I'm assuming this is like a bit of mini-ramp to smooth the transition in height?
 
Reply
Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: