DIY Network

Sub-Floor and Radiant Heat Flooring From "Bathroom Renovations" episode DBTR-201

It was time to turn our attention to Kelli and Stuart’s bathroom floor.

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	A tired '70s style bathroom is...
	transformed into elegance and beauty.

Materials:

Wrench
Small bucket
Gloves
Eye protection
Tape measure
Pencil
Chalk line
Circular saw
Pry bar
Hammer
Speed square
Hole saw
8 penny ring shank
Staple gun
Ohmeter

Figure A

The young couple are busy with three kids, so they decided to bring in professional help on certain parts of their project. After gutting most of the bathroom, they hired a plumber to remove the old wet wall. A wet wall is a common name for any wall that contains plumbing (figure A).

The plumber moved the water supply lines and the drain to the middle of the wall which is where it needs to be for the new claw foot tub.

Sub-floor

Figure B

Once again, as is often the case when you get into demolition, we discovered a problem. The floor was sagging (figure B).

Fortunately, the revelation was not that bad, but we did want to make sure that the floor was level for the claw foot tub. An insert tub can be leveled with shims, but with the claw foot tub the feet are exposed and the floor needed to be level to ensure that the tub was.

1. An option was to do what the previous owners had done and put in a lot of shims under the sub-floor, but we were using a liquid self-leveling floor so it was more important for us to get the firmest base for that as possible. We put in small spacers on the joists and then placed the plywood on those.

2. The floor had been cut up many times over the years. We needed to create a straight line where the new plywood would meet the old.

3. We measured out 36 inches from the wall in two locations (figure C) and snapped a chalk line (figure D).

Figure C

Figure D

4. With a circular saw, we cut out the old plywood. We then used a pry bar to lift out the old piece (figure E).

5. The new plywood was cut so the seam could rest on a joist (figure F).

Figure E

Figure F

6. As for all the debris in the floor, we just left it...it doesn’t hurt anything and it will even act as a sound barrier.

7. The last sheet of plywood was dry fitted up to the drain for the new tub.

8. The drain was lined up and a mark was made on the plywood.

Figure G

9. The distance from the wall to the center of the drain was measured. That measurement was transferred to the plywood along the center line (figure G).

10. Eight penny ring shank nails were used to secure the plywood to the joists. The ring shanks help keep the sub-floor from shifting or squeaking

11. We ran the circular saw along the seams between the sheets of plywood. This creates a gap for the sheets to expand and helps prevent the tile from cracking.

12. We nailed in a piece of scrap lumber to act as a dam for the self-leveling underlay (figure H). The scrap piece was later removed.

13. We used duct tape to seal the seams between the sheets of plywood (figure I). This will keep the liquid underlay from leaking through until it sets up.

14. Two inch duct tape was folded into an L shape to seal the edges (figure J).

Figure H

Figure I

Figure J

15. We also applied foam tape around the perimeter of the room (figure K). This will allow for expansion between the sub-floor and the wall and also creates a thermal barrier to increase the efficiency of the in-floor heating.

16. A plastic lath was placed to give the floor more stability (figure L).

Figure K

Figure L

Safety Alert: Never use metal lath when installing electric in-floor heat products. Metal lath can conduct electricity.

Radiant Heat Flooring

We were then ready to get started on the installation of the radiant heat.

1. Staple down the spacing strips around the perimeter of the heating area (figure M).

2. Take a minute to check the product with a multi-meter to make sure it wasn’t damaged during shipping (figure N). The label on each unit tells you what the OHM reading should be if it’s working correctly (figure O).

Figure M

Figure N

Figure O

3. We placed the cold lead on the wall near where it would be connected to the thermostat (figure P) and ran out the cable to the nearest spacer strip. The cold lead is a non-heating wire that runs from the thermostat down to the floor.

4. For our application, we wanted to separate the wires by two inches (figure Q).

Figure P

Figure Q

Figure R

5. Place a floor sensor between the wires (figure R). It will read the temperature of the floor and communicate with the thermostat.

RESOURCES :

Gyp-span Radiant Gypsum Concrete
Brand Name: Hacker Industries
Manufacturer: KMAC, Inc.
21575 Hwy. 7, P.O. Box 548
Hutchinson, MN 55350
Phone: 1-320-587-9697
Scott Ryan, GM: scott@kmacmn.com
Website: www.kmacmn.com

Floor Warming System
Floor Warming Cable
Brand Name: SmartRooms
Model #: FW23-120

Spacing Strips
Brand Name: SmartRooms
Model #: SS25

Thermostat
Brand Name: SmartRooms
Model #: STP-GFI-120v
Manufacturer: Therma-Ray, Inc.
670 Wilsey Rd., Unit #6
Fredericton, New Brunswick, Canada E3B 7K4
Phone: 1-506-457-4600
Kevin Kilbride, President: kevink@thermaray.com
Website: www.thermaray.com

GUESTS :

Shane Kretsinger
VP, Operations, Autumn River
2520 Coon Rapids Blvd., Ste. 250
Coon Rapids, MN 55433
Phone: 1-763-323-8876
E-mail: shane@autumnriver.biz