Teracota Roof Project

zdiver

I have a 500 sq. ft. concrete slab roof on a vacation home that I'd like to recondition and lay tile on top of for the purpose of transforming it into a sundeck. Currently it's asphalt roll based and leaks in one corner.

The leak in the corner is underneath a 3-400 gallon water tank which will probably be rebuilt towards the side of the house to maximize space for the sundeck.

Since the roofing is about 15 years old and needs to be redone anyway I thought I'd entertain the idea of tiling it directly afterwards and ask for some much needed advice on surface preparation.

Thanks in advance!

theroofinggod

what`s the pitch,and life expectancy of the roof?

zdiver

Water drains off to either side so if it slopes it's probably 1/4 inch per 10 feet or so. Baiscally it's a flat level rectangle 20' x 25' with the exterior wall extending approx. 4 to 6 inches past roof height, or what will be the new floor.

I was going to post a picture of the roof construction but I need 13 more posts before I can do that. To me however, it looks like an engineered concrete block system with prestressed concrete girders and matching cast blocks about 20" long spanning them. My understanding is that on top of this lie a few inches of reinforced concrete and what looks like torch down above that. The torch down must go as it's 15 years old and rotting.

The house was originally designed to handle another story but I don't think I want to do that. I'd prefer to leave it 1/2 shaded with a patio/sundeck for now.

I do have a picture that depicts the roof/floor construction from underneath but I'll need to figure out how to get it up here. Let me know if you think it's needed.

Grumpy

I've seen some disasters with builders pouring mortar directly on top of modified bitumen to level the roof out then tiling right on top of that. Next thing ya know, the roof didn't leak before the tile and it does after the tile and the roofer and tile guy are pointing figers at each other.

I think your best bet is to put some kind of non-permenant surface over a very very good and long lasting roof. Perhaps paver bricks instead of tile. Nothing single ply when the roof is going to be used for foot traffic or is going to have items placed ontop of it. IN addition, I'd also place some form of seperation, or padding, between what ever you decide to place on it, and the roof it's self. This could simply be a piece of loose laid single ply. Often we use a piece of smooth modified bitumen membrane to act as a padding.

zdiver

Perfect, that's the type of information that I suspect will really be helpful in the long run.
Wow, that's an intriguing idea. Couple questions right off the bat though. Do you think I could use some sort of insulation as the padding between roof and tile and can you give examples of what in your estimation constitutes a "very very good and long lasting roof"? If the torch down needs to come off, what's the best method to do it and how clean does it need to be?

Grumpy

Insulation could be used i would suspect if it can withstand the dead load and especially the live load of foot traffic. I'd fear it might need to be faced with some kind of high PSI fibercement such as securerock made by USG. I say Secure rock because I know it is supposed to be very resistant to water. There may be others. I fear if you place some polystyrene it will eventually crush and break down.

If i were to do this on my home I would install a 4 ply modified bitumen roof system which would be either torch applied or set in hot asphalt. 4 plies you say? Fiberglass base sheet half lapped with 18" exposures and then a smooth 4 millimeter modified bitumen with a 5 millimeter granulated modified bitumen over it. Then another loose laid smooth modified bitumen as a padding/seperation.

There are many good roofing systems on the market, gooda t keeping the water out, but when it comes to foot traffic I feel the only thing that can be replied upon would be layers of redundancy, which is why I suggest the 4 ply system.

By the way, if you had a fine arts collection directly under neath I'd even say to coat the granulated modified bitumen with a fully reinforced urethane elastomeric system. Jeez I couldn't imagine anything getting through that roof other than a bullet.

reveivl

Where are you? I ask for freeze/thaw cycles. I don't see why you couldn't tile it with the correct prep. You'll have to remove ALL of the residue from the torch on for starters. Make sure the surface is flat and clean to a fairly high tolerance, and then some kind of membrane (Noble, Ditra etc.) thinsetted to the concrete, with the seams taped appropriately then thinset and tile.

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theroofinggod

I`d put Grumpy`s roof w/a paver system above it,ALLIED has some really nice vendors for that material