[cromjoeb]

I have an outdoor balcony that is waterproofed with asphalt and tar. Is it reasonable to lay light weigh cement over the tar surface in order to provide a nicer looking finish?

[tickle]

I don't think it is likely the cement will cure

[N0help4u]

Edited ---I didn't see the heading on my cell. I agree with ma0641 below

[ma0641]

Make a nice IPE wood deck.

[joypulv]

'Asphalt and tar?' Do you mean tarpaper, with the seams coated?
A tarred surface (not paper) would rarely be done on just a balcony, because it's very expensive. Usually a big flat roof.
There is no way you can put concrete over either one, because it will crumble.
Concrete has to have a deep substrate of gravel and sand, and has to be at least 3 inches thick. It would be too heavy too.
Get some Durarock, which is 1/2" concrete board, 3' x 5', put it down and carefully waterproof all the seams, and tile over that, perhaps.
What's most important is that water doesn't get through below, not even through one seam or nail or screw.
I personally would just decorate with chairs, planters, and an outdoor carpet.

[joypulv]

A tarred or tarpapered balcony assumes that it needs to protect what's below, like a porch.
A 'deck' assumes that rain goes through 1/4" spaces between each board, and falls on the ground or concrete or pavers.
Plus ipe has fallen out of favor because it is not only very expensive, it will destroy several saw blades.
If you go with a wooden 'deck' on top of the existing protective surface, make sure it isn't attached. To anything but itself, like a bunch of elegant pallets.

[cromjoeb]

Yes joypulv, it's a combination of fiberglass, asphalt based storm shield and tar. One of the companies in our area of Texas commonly uses this process to waterproof balconies. It's referred to as a 3-ply modified.The process starts with a fiber base nailed to the deck, layered with storm shield. The final coat is hot tar mopped in and smoothed over. Based on the previous results, I think the process is solid. My question is can we go over the top of the tar layer with tile or some other mortar/cement material?

[joypulv]

I am dubious, because of different expansion and contraction rates.
You have wood and tar in the Texas extremes of heat etc, and then you want to put an inflexible material on top.
Talk to some local contractors. I'd only agree with something mostly 'floating' such as Durorock that is only attached in a few places, has expansion joints between each panel, and is covered with thinset and tile.

[tickle]

@joy. You would only agree with something mostly floating? How many of these have you done ?

Can you give some links to this work actually being accomplished they way you envisioned ?

I have done home renovations, and am in the middle of one. I get right in there with all the tools of the trade, but I absolutely could not advise the OP on how to accomplish this. How can you ?

Provide a link, cause I don't see many of our experts in this field stepping up the plate.

[joypulv]

No link, tickle, no one would do what this person wants to do that I know of, no one has ever done it that I know of.
It is counter-intuitive based on general knowledge of materials and the way they expand and contract.

[cromjoeb]

No link, tickle, no one would do what this person wants to do that I know of, no one has ever done it that I know of.
It is counter-intuitive based on general knowledge of materials and the way they expand and contract.

Go to YouTube and type in "Rodriguez Roofing Balcony Water Proofing". The video shows the whole process. I've visted post job installations before tile is installed and afterwards. The homeowners I talked to have had no issues going on for several years after the installation. I've also spoken to flooring companies who come in after the tar is setup and lay a metal stucco lath on top of the tar layer. The next step is mortar followed by the tile of choice.

I welcome your comments.

[joypulv]

OK... I'm going to pass on looking at it, because I'm in the north and just wouldn't even think of trying it.
Wood + tar + stucco, all on a horizontal surface, wouldn't last here.
If I'm wrong (about the north), I'm wrong, but I don't think so.
I guess it works in the south. True of many things.

[joypulv]

I looked at the video, which is a very nice fiberglass reinforced multi-layer with tar. It's not clear what the deck under it is! The whole house looks like stucco! You don't even say what your substrate is.
It doesn't mention any lath/stucco/tile on top, so you have to go by the people you know who have done this. Not one of the usual building contractors has weighed in on this.

A balcony with 3 enclosed sides is extremely rare where I am in CT or anywhere I have lived in the north. Any bit of water in the seams will freeze in the grout and expand. That's just on the surface. More havoc underneath, from moisture coming up from below, and in from the sides. Any product, even tar, has a life span. Good luck.

[cromjoeb]

I looked at the video, which is a very nice fiberglass reinforced multi-layer with tar. It's not clear what the deck under it is! The whole house looks like stucco! You don't even say what your substrate is.
It doesn't mention any lath/stucco/tile on top, so you have to go by the people you know who have done this. Not one of the usual building contractors has weighed in on this.

A balcony with 3 enclosed sides is extremely rare where I am in CT or anywhere I have lived in the north. Any bit of water in the seams will freeze in the grout and expand. That's just on the surface. More havoc underneath, from moisture coming up from below, and in from the sides. Any product, even tar, has a life span. Good luck.

My substrate is treated wood. The video doesn't address what goes on top of the tar because the roofing company doesn't get involve with that. That's left up to the homeowner. I have visited job sites before the tile install and after, some of which have been installed for several years. I guess it works here since we don't have the wide variances in temperatures that you have in the north.

Thanks to all for your feedback.