Outdoor tiled table top

[str]

I plan to tile an outdoor table top - using exterior ply as a base but do I need to be careful of what type of tiles I buy?

The table will be left out all year, so I do not want to have cracked tiles due to frost.

 

[Richard C]

Don't use ply as a base; even exterior grade ply is still wood, wood is not dimensionally stable, it expands & contracts depending on moisture content. OK for a bathroom floor but even then the underside & edges should be sealed against moisture but when exposed to the ravages of an outdoor climate it won’t last long; moisture will be absorbed into the underside of the ply which will expand, curl & your tiles will fall off.

You need to use a cement based board but not over timber supports as these will still distort. Check your tiles are frost proof; a decent flexible powder cement based adhesive, (not tub mix) & grout are frost proof down to around -30 degrees C but I’ve never used them outside so check the spec.

 

[str]

The frame is aluminium - I am actually wanting to replace the wooden top because the weather has taken its toll on it.

Will a cement board be strong enough to support, say the weight of someone leaning over the table? table top dimensions are approx. 1m x 2m

the cement board I have seen is from the big sheds and for use in bathrooms instead of plasterboard - I assume you don't mean that?

 

[Richard C]

Well something very similar that’s for sure; but, as you’ve figured, cement boards aren’t designed to be used unsupported. Although it’s stable & quiet tough, it is rather brittle if not fully supported & this is going to be fairly difficult to achieve on a patio table. All the outside use tiled tables I have seen are made from a concrete base & the tiles fixed straight onto that.

A ply table top would need to be a 22 -25mm thick or it’s going to flex & there go your tiles & it must be thoroughly sealed so that no moisture cant get in or your going to have expansion/contraction in the timber & there go your tiles again; I wouldn’t hold out much hope achieving 100% sealing. You’re still going to have a problem with the tiled surface unless you tank it; it’s only the very expensive epoxy adhesives & grout that are & truly waterproof & non absorbent. All other waterproof adhesive & grout is only waterproof in the sense it wont disintegrate when wet, it will still absorb water &, in an outside environment, this will inevitably permeate down through the grout into the ply base below, the ply expands & there go your tiles again.

Tiling outside tables is not something I have any experience with but I understand very well how the materials behave & what happens if you get it wrong in a bathroom environment & I would think the chances of such a table lasting more than one summer/winter cycle are not very good. Taking into consideration the work involved, likely cost of materials & the risk of early failure, it may be easier & cheaper to buy a new patio table.