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rcrlauff
Tile on Kitchen Floor

First, I'd like to say that I am a big fan of TOH and subscride to the magazine. I own an old farm house built in 1889.
I am planning to remodel my kitchen. The room will be 13.5 ft by 26 ft. The floor joists are 2"x 8" rough cut, 16" on center with a 13.5 ft span. The space below the joists is on average 3" with dirt below(not much of a crawl space). My plan is to reinforce the joists by glueing and nailing 5/8" plywood strips on one side of each joist, and place two rows of blocking(bridging) evenly spaced. I then plan to insulate with fiberglass batt (R19) resting on foam board insulation attached between each joist space. The sub-floor will be two layers of 5/8" plywood staggered and offset to ensure no joints fall on top of each other. The finish floor will be either 12" or 16" tile. I want to heat the space with radiant floor heat. I have purchased an outdoor wood furnace(Central Boiler) as a secondary heat source for the house with an oil-fired furnace(forced-air) as the primary heat source.

The plan for heating the floor is to attach 30 lb tar paper on the sub-floor, run two circuits of 1/2" pex tubing, and float a mortar bed approx. 1" thick over the entire floor as a base for the tile.

I'd like to know if this is a sound plan and if I am missing any important steps. I believe I should be installing wire mesh in the mortar bed but it would have to go on top of the pex. Then, it would be difficult to use screed strips for floating the mortar bed.

Can I lay the bed in two lifts with the wire mesh in the second lift?

Digging out below the floor joists in order to install the pex and insulation is my very last option, again there is only 2" to 3" inch space below the joists.

Any input or assistance would be greatly appreciated.

aretert
Ok
rcrlauff wrote:

First, I'd like to say that I am a big fan of TOH and subscride to the magazine. I own an old farm house built in 1889.
I am planning to remodel my kitchen. The room will be 13.5 ft by 26 ft. The floor joists are 2"x 8" rough cut, 16" on center with a 13.5 ft span. The space below the joists is on average 3" with dirt below(not much of a crawl space). My plan is to reinforce the joists by glueing and nailing 5/8" plywood strips on one side of each joist, and place two rows of blocking(bridging) evenly spaced. I then plan to insulate with fiberglass batt (R19) resting on foam board insulation attached between each joist space. The sub-floor will be two layers of 5/8" plywood staggered and offset to ensure no joints fall on top of each other. The finish floor will be either 12" or 16" tile. I want to heat the space with radiant floor heat. I have purchased an outdoor wood furnace(Central Boiler) as a secondary heat source for the house with an oil-fired furnace(forced-air) as the primary heat source.

The plan for heating the floor is to attach 30 lb tar paper on the sub-floor, run two circuits of 1/2" pex tubing, and float a mortar bed approx. 1" thick over the entire floor as a base for the tile.

I'd like to know if this is a sound plan and if I am missing any important steps. I believe I should be installing wire mesh in the mortar bed but it would have to go on top of the pex. Then, it would be difficult to use screed strips for floating the mortar bed.

Can I lay the bed in two lifts with the wire mesh in the second lift?

Digging out below the floor joists in order to install the pex and insulation is my very last option, again there is only 2" to 3" inch space below the joists.

Any input or assistance would be greatly appreciated.

I tend to agree mostly but im still not sure I understand everything here

misfitter
Re: Tile on Kitchen Floor

I am not sure why you are using tar paper since when you heat it up (as on a roof) it tends to be sticky. This is a great site to use as a reference.

www.RadiantandHydronics.com

I would use a reflective material (not tar paper). Then the wire mesh wouuld go down and the pex would be secured to that. Then you can add the 1" motar bed. Maybe. You have to know if you are going to run the PEX lines 12", 18", or 20" apart. Then also, is this the only room? What is your heating source? Are you ready for this. Good luck. Proccess of elimination.

goldhiller
Re: Tile on Kitchen Floor

Gotta say that I am very much skeptical concerning the addition of the 5/8" ply and expecting that to add enough rigidity to these 2x8s spanning 13.5'...........and getting an end result that can support tile and all live loads without having problems with tile cracking because of deflection.

Are these full dimension 2x8s? Clear or knotty? Species? Are they structurally comprised from years of moisture from the underlying dirt? Might wanna think about laying some 6 mil plastic on the dirt before you close up to stop or prevent that from happening in the future.

Are these joist ends sitting on a ledger? Just toenailed? Or are you adding joist hangers?

I would likely also suggest something other than 30# for the same reason. Agree it would be best to have something there to prevent water from the mortar soaking into the subfloor. The reflective should kill two birds with one stone.

If it was me.....I'd want 1 1/2" of mortar bed. I'd sleep better. Call me a chicken.

Install your basic info here .... http://www.johnbridge.com/vbulletin/deflecto.pl ...and I think you'll see that your floor structure as is.....doesn't qualify for tile or stone........or might just barely for ceramic tile. With addition of 5/8" ply "reinforcement".......still questionable in my mind. That because the joists are almost certainly rough-cut which means you can't get a good glue bond between joists and ply.

rcrlauff
Re: Tile on Kitchen Floor

After much research, I've have found the solution on the "John Bridges Tile forum" website. They have a nifty tool called "Deflecto". When given floor joist demensions, species, and span, the tool determines what you can or cannot use as a finish floor. In my case, 13'5"span using 2"x8"s was not suitable for 12" tile. The fix I used was to install a beam cutting the span in half. I also received information on a product made by Schlueter called Bekotec which is a grid system designed specifically for pex tubing in a mortar bed. Expensive, but worth the peace of mind.

GoshenJon
Re: Tile on Kitchen Floor

More of a question than an answer - Does there need to be some form of vapor barrier to keep the insulation dry?

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