# Heated floor as part of renovation - advice wanted, espescially re: floor prep.



## Bastien1337 (Dec 20, 2010)

I think the confusion comes from Angus misinterpreting the OP. Or the OP using incorrect terminology which gave Angus the false interpretation 

*Existing bathroom is a '50's era home with the original mud bed (the 'plank between the joists' style with the joists hatcheted into points). I know this because I redid their other bathroom (point is, if I bust up the mud bed, I'll have to install new sisters on the joists to make a level surface to support a new plywood subfloor). *
*
If you don't want to remove the existing mud bed, why the need for Ditra? The mud bed is already uncoupled. *


the dropped mortar surface isnt a mud bed, its something else. There is no uncoupled mud bed in this situation. The tile is bonded to this dropped mortar system and it is an integral part of the house. I ripped one up last year that had a huge crack running through it.

the tops of the joist are chamfered and then they pour another type of mortar layer on top of this dropped system which binds the two then tile on top.


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## angus242 (Oct 20, 2007)

You got that right. I have never seen that style of floor in my area. I think oh so long ago, Bud Cline told me about this elusive beast. Doesn't make any sense to me why they'd do it that way. What's to keep more mortar falling through than you want?

Oh well. We've at least straightened this discussion out now! :thumbup:


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## jarvis design (May 6, 2008)

Bastien1337 said:


> I think the confusion comes from Angus misinterpreting the OP. Or the OP using incorrect terminology which gave Angus the false interpretation
> 
> Existing bathroom is a '50's era home with the original mud bed (the 'plank between the joists' style with the joists hatcheted into points). I know this because I redid their other bathroom (point is, if I bust up the mud bed, I'll have to install new sisters on the joists to make a level surface to support a new plywood subfloor).
> 
> ...


Yep, ripped out the exact same set-up in London a few times...a lot of these had out of plane cracks


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## Bastien1337 (Dec 20, 2010)

I shoulda taken pics of it, theres tons of these old style builds in Toronto.

ledgers are run along the length of the joists near the bottom. then planking spans the ledgers running perpendicular to the joists. some rubble fill and some type of mortar is poured in and leveled out to the top of the joists. The joist tops are chamfered to a point to allow this _mud bed_ to essentially be continuous across the floor at the upper most part. This allows the next layer of mortar to span the entire floor almost uninterrupted by the wood of the joists which creates a solid base for tile.

Then either terrazzo or tile is laid on top. It is an unbelievable PITA to rip out.

You can hear the house breathe a sigh of relief when all that weight is gone.

The joists are usually left mangled and severely sagged. Much re-levling and sistering needs to be done in order to pull the floor back into a usable shape.


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## Panzer5 (Oct 21, 2008)

Bastien1337 said:


> I shoulda taken pics of it, theres tons of these old style builds in Toronto.
> 
> ledgers are run along the length of the joists near the bottom. then planking spans the ledgers running perpendicular to the joists. some rubble fill and some type of mortar is poured in and leveled out to the top of the joists. The joist tops are chamfered to a point to allow this _mud bed_ to essentially be continuous across the floor at the upper most part. This allows the next layer of mortar to span the entire floor almost uninterrupted by the wood of the joists which creates a solid base for tile.
> 
> ...


Absolutely perfect description of what I'm working with. 

And you're right - they're a monster to remove & prepare a new subfloor around.


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## gideond (May 17, 2007)

I had assumed the same thing when you said Mud Bed. I also assumed electric heat was you goal. My fault there. Electric is probably the most common heat type in renovations. I never even considered the kind of system you are using. Regardless, in your situation I'll stick by my original recommendation with the use of Ditra. In this case Electric will be a far easier and less expensive solution. You'll have to go with different methods and materials as already discussed to do it with the kind of system you are currently considering. The price would be enormous.


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## Panzer5 (Oct 21, 2008)

I saw a video where the guy mixing the self leveling compound used a kind of spiral stirrer rather than the usual egg beater.

Is this really necessary? (i.e. do I need to go out and buy another tool) or can I get away with using my trusty egg beater on the drill?


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## HerrBag (Nov 27, 2009)

I've used both, mainly based on quantity..The spiral for smaller batches


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## angus242 (Oct 20, 2007)

Panzer5 said:


> I saw a video where the guy mixing the self leveling compound used a kind of spiral stirrer rather than the usual egg beater.
> 
> Is this really necessary? (i.e. do I need to go out and buy another tool) or can I get away with using my trusty egg beater on the drill?


The spiral or reverse cork screw looking mixer is to prevent introducing air into the mixture. It actually pulls up from the bottom instead of pushing air downwards. For your next beater you should get one. There are just 1 more small/cheap insurance policy to making sure your thinset mixture is beautiful!


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## Groutface (Jan 20, 2011)

I've done my dads bathroom above the bar he owns and came across the exact situation very old building! We were able to rip the top layer of concrete off and couldn't take the rest out in between the joists because of pipe and water line running through the concrete so I grinded down any high spots them 3/4 Ply then 1/2 ply then self leveler then ditra then tile...what a difference in deflection from the first layer of ply ! Thumbsup!


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## Groutface (Jan 20, 2011)

Groutface said:


> I've done my dads bathroom above the bar he owns and came across the exact situation very old building! We were able to rip the top layer of concrete off and couldn't take the rest out in between the joists because of pipe and water line running through the concrete so I grinded down any high spots them 3/4 Ply then 1/2 ply then self leveler then ditra then tile...what a difference in deflection from the first layer of ply ! Thumbsup!


Suprised also that there was no lath system of any kind! Just "pointy joists". Only time I've seen it. The building sighed in relief when we ripped it!


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## Panzer5 (Oct 21, 2008)

"Pointy Joists" and thick mortar beds are the norm around here. It's not uncommon to find galvanized piping in the mortar either - mostly because (apparently) back in the day, plumbers didn't believe in putting pipes in the wall cavities. 


Typically there's plumbing, HVAC and electrical underneath the tile bed - which, believe it or not, intereferes with sistering the joists to create a stable subfloor. Also, typical is that the homeowner wants to keep her 800 lb cast iron corner tub (which must have been hoisted into place shortly after the foundation was poured and then enjoyed the signal honor of having the whole house built around it...)... more fun!

I've only seen the metal lath used in the walls - broke a sledge trying to get that out the first time. Since then, I've bought a set of really big crow bars - and we take them down using chants unheard since the pyramids were built.


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## Groutface (Jan 20, 2011)

Hahahaha....awesome!


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