Can I tile exterior deck that has Polyurethane coating over hardi board?

Question

My builder sprayed my exterior walk-out deck on the 2nd floor over the patio with a Polyurethane coating to provide a water-proof coating. The floor feels a little rubbery with undulations due to breezy conditions when he sprayed. Since the Polyurethane is grey in color, I would like to tile it - any size of tile is ok - but not sure if I can. Builder said I can tile after I apply thinset on top of the Polyurethane. I consulted Home Depot, the lady there recommended using a concrete back board on top of thinset. I don't want to add too much weight to the deck. What can I do? Thanks

apprciate the replies. Just to clarify, the deck was build by a professional decking company recommended by my builder. They knew that I was going to tile and had added extra support. But I still do not want to add more weight than necessary. It will be a private sit-out with a couple of louge chairs to enjoy the view, no partying. I I am not sure, if I can tile over the poly urethane coating by applying thin set. Second, since the polyurethane is a slightly rubbery material, will the tiles break after I lay them? or can I counter it by using a smaller tile size? I am planning to use all exterior material & will allow for expansion / contraction when the tile is laid. Thanks again.

Answer 1

First of all -you don't want to tile your deck! I'm telling you you don't want to do it. No matter how good the structure is it will flex and you'll just end up with broken tiles - cut your feet - get an infection and they'll have to cut off your legs. Call your decking company and ask about alternative surfaces.

Answer 2

If the deck already feels "rubbery"...(I assume you mean it moves under weight)...then youve already got a problem... and you do not want to add ANY more weight to it, until you get this fixed.

I'd say you are going to have to add some support to the deck. As the others have suggested, I also recommend that you talk to a structural engineer. You may be able to find one thru an architect firm. That will at least give you a place to start.

When installing tile, you do not want ANY movement in the sub-floor underneath it. The mortar will crack and come out, and you may even have tiles that will break. If you put too much weight on a structure not designed for it.... it's a disaster waiting to happen. (I recall a news story not too long ago, about a deck that collapsed, when the second floor residents decided to have a party... and the deck wasnt even 'full' of people) Be Safe!

Good Luck!

Answer 3

Tile over a wood deck? That's kind of weird. I've never seen that done before, but you would definately need to add some sort of plywood or Durock (cement board) in order to make the deck more of a monolithic surface. (and screw the heck out of it, probably every 6" on center) Wood decks have a tendancy to shrink and move a little, which is why I don't think applying a ceramic or porcelin type tile would be a good idea. However, if you use a thinset or type of tile glue that is approved for exterior use, I don't think the poly is anything to worry about. I think that's the least of your worries! (sorry) I hope I understood your question.

Answer 4

First step is to have a structural Engineer out to look at the deck itself -- including the load ratings for the structure as built BEFORE you do ANYTHING At all -- and I mean ANY thing.

That it is a 2nd floor deck is a problem to begin with, and the Concrete Backerboards are HEAVY to begin with, the TILE Weighs even MORE, then add the Mortar and the Grout -- and that COULD be a recipe for disaster of the kind where if you go out on the deck and stand there, it COULD break under the additional weight of EVEN one person!!!!!

So go first to the Structural Engineer and NOT just listen to the builder -- he does NOT have the Engineering Experience to evaluate the load limits of the structure as it currently exists. I'd make sure that the structure can be used for what you want it to be used for 1st and then any additional weight and how it needs to be modified.

Answer 5

Simple and easy to do.. get a sander, sand off the polyurethane, so the clue will adhere to the wood.. you might want to add some floor glue, to make sure it crabs.. Also when you are done laying your tile, make sure you caulk all the pieces that are hooked together to protect water from rain/weather getting under the tile, it will loosen the glue, and it will come up if you dont caulk it.. Put a clear color and just run it on each crack and let it dry overnight.. Don't lelt anyone walk on it.. Hope this works for you... Good Luck!!!

Answer 6

I assume he used a grinder with a masonary blade and this does create huge amounts of fine dust. Did he cut it inside or out. If out you shouldnt have much dust inside.If inside wear a mask and use a damp rag to wipe all surfaces where dust is and throughly vaccum the floors I dont know about silicosis but would imagine it would take exposure over a long period of time. Seek medical advice. However this dust is not good for you USE A MASK AND EYE PROTECTION and make cuts outside. Its not worth the risk