Floating a Mortar Bed on a Balcony

[pestocat]

I will be floating a mortar bed on a balcony 4 ft. wide by 11 ft. long. There is nothing to confine the outside edges of the bed. How is this non confinement handled. Do I float to the edge and use a steel trowel to make a sharp cut just short of the edge and just make sure I have it compacted well. Maybe use my hand to confine the mortar at the edge. A little excess will fall off the edge. Is this the way it is done? After reading Michael Byrne's article "Tiling an Outdoor Countertop", it seems I could add temporary edging to the bacony facia that would be at the finish height of the mortar bed. Seems like a solution.

[tjbnwi]

Re: Floating a Mortar Bed on a Balcony

You will have to form the edge some how some way. Make sure you use a release agent on the forms.

Tom

[Tom Bainbridge]

Re: Floating a Mortar Bed on a Balcony

as tjb says your formwork needs an edge to confine it and like he says use a release agent

use one of these before it sets

http://www.my-tool-shed.co.uk/m15/Ma...1566_1731_2873

and build your formwork so you can strike it without damaging the completed artical

[Lavrans]

Re: Floating a Mortar Bed on a Balcony

I will be floating a mortar bed on a balcony 4 ft. wide by 11 ft. long. There is nothing to confine the outside edges of the bed. How is this non confinement handled...

I could add temporary edging to the bacony facia that would be at the finish height of the mortar bed. Seems like a solution.

That's what I'd do- it's a much easier way to ensure that your elevations will be good. Just be sure not to compromise your flashing and/or waterproofing. How is the edge going to be finished? What's underneath that mortar bed? Got waterproofing and flashing?

Tom- Why would you worry about forming a radius edge? Assuming it's going to get tile (mortar bed sort of implies something like that) I'd just knock off the sharp edge after pulling the form.

I also wouldn't use a form release myself. I mean, it might not contaminate the mortar, but I'd rather not risk it. I might wrap it in plastic if I was worried, but most of the time only a little will spall, and that will get covered with tile. Hopefully.

[Robert Z]

Re: Floating a Mortar Bed on a Balcony

For drypack, you don't need any release agent but you do need to have something there to form the edge, We use whatever is handy, but usually it's a strip of 2x ripped to the proper depth and then shimmed to level.

I'm assuming this balcony is concrete? If so, you should bond the deck mud with thinset to the slab.

Schluter makes various profiles that you can use to trim out the edge.

[pestocat]

Re: Floating a Mortar Bed on a Balcony

That's what I'd do- it's a much easier way to ensure that your elevations will be good. Just be sure not to compromise your flashing and/or waterproofing. How is the edge going to be finished? What's underneath that mortar bed? Got waterproofing and flashing?

Tom- Why would you worry about forming a radius edge? Assuming it's going to get tile (mortar bed sort of implies something like that) I'd just knock off the sharp edge after pulling the form.

I also wouldn't use a form release myself. I mean, it might not contaminate the mortar, but I'd rather not risk it. I might wrap it in plastic if I was worried, but most of the time only a little will spall, and that will get covered with tile. Hopefully.

Lavrans,
The plywood deck is getting waterproofed and flashed by a hotmop application. The roofing contractor will apply gravel stop at outside edge and flashing around the door opening bottom area. I want a square edge at the outside, no radius. The finish surface is tile. And the edge finish would be the exposed mortar be.

[tjbnwi]

Re: Floating a Mortar Bed on a Balcony

Be very carful with the exposed mortar. Thinset is not water proof, it will dissolve in water, very easily.

You may want to consider a Schluter trim piece for that application. You may also forgo the whole hot mop idea and use nothing but Schluter products.

http://www.schluter.com/

Tom

[Robert Z]

Re: Floating a Mortar Bed on a Balcony

Be very carful with the exposed mortar. Thinset is not water proof, it will dissolve in water, very easily.

You may want to consider a Schluter trim piece for that application. You may also forgo the whole hot mop idea and use nothing but Schluter products.

http://www.schluter.com/

Tom

Tom, where did you get the information that thinset will dissolve in water?

[Lavrans]

Re: Floating a Mortar Bed on a Balcony

Be very carful with the exposed mortar. Thinset is not water proof, it will dissolve in water, very easily.

You may want to consider a Schluter trim piece for that application. You may also forgo the whole hot mop idea and use nothing but Schluter products.

http://www.schluter.com/

Tom

Hopefully the mortar bed isn't made of thinset. Most hhinset can't be set more than 3/16 thick. A mortar bed should be a sand mix. That shouldn't dissolve either, especially once the tiles are installed. Just remember to change to a medium-set if your bed turns out not quite perfect.

Whatever waterproofing system used, make sure to use a complete system with all the parts. Double check to make sure the person installing the hot mop put the correct slope on their pan and that it's run up the walls far enough.

[tjbnwi]

Re: Floating a Mortar Bed on a Balcony

I should have qualified may statement. This is an observation on my part.

I have washed mortar off a trowel after it has dried. If you drip water on thin set it will soften that area. Drop some cured thin set in a bucket of water it will dissolve.

The covered surface is not the issue. it is the exposed edge I am concerned about.

Customs web site list their mortar for an exterior dry area install, thin set at 1/4".

http://www.custombuildingproducts.com/welcome.aspx

Again the statement is based on observation.

Tom

[Lavrans]

Re: Floating a Mortar Bed on a Balcony

Tom- Custom's "dry area" is for when the thinset is used to install over drywall. Thinset shouldn't dissolve, although if it's too wet it can be quite a bit weaker than when properly mixed. I've found it to be fairly comparable to concrete when allowed to fully cure on a trowel. A little softer, but I think that's because of how much and how fine the sand is- it's meant to be closer to grout than concrete- I think because it allows some elasticity; the tile and substrate often move at slightly different rates, if the thinset is too brittle, the tiles could pop. But that's conjecture on my part...

[BeachBoy]

Re: Floating a Mortar Bed on a Balcony

I'd recommend a more substantial water proofing system. I like and use Merkrete's 747 System with stainless steel flashing. Here's a link:
http://www.merkrete.com/merkrete/dual747-1.htm
They provide a 10 year limited warranty.

Also, on their web site it says it provides "Duel Protection", which could be fairly handy if something leaks and you have to fight the homeowner. ;-)

I did a couple of large 2nd floor decks with the product and was pleased with it.

[tjbnwi]

Re: Floating a Mortar Bed on a Balcony

Again just something I have noticed, I know I would not leave an exposed edge.

Tom

[pestocat]

Re: Floating a Mortar Bed on a Balcony

Hopefully the mortar bed isn't made of thinset. Most hhinset can't be set more than 3/16 thick. A mortar bed should be a sand mix. That shouldn't dissolve either, especially once the tiles are installed. Just remember to change to a medium-set if your bed turns out not quite perfect.

Whatever waterproofing system used, make sure to use a complete system with all the parts. Double check to make sure the person installing the hot mop put the correct slope on their pan and that it's run up the walls far enough.

Lavrans,
The mortar bed will be made from bags of mortar mix and using an ad-mix in place of water for extra strength and water protection. The slope is built into the balcony, it has a 1/4" per foot slope. Also thinset once cured does not dissolve in water. Thinset, mortar, and concrete all use water to cure. Thinset is not drywall compound, it is entirely different. Thank you for all the comments they are most helpful.

[Lavrans]

Re: Floating a Mortar Bed on a Balcony

Thinset is not drywall compound, it is entirely different.

It isn't? Drat! That must be why the tiles keep falling off in my shower...