Tiling Over Outdoor Wood Deck [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


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Bear B
09-18-2010, 09:44 AM
Experts: I sure do need some guidance. Am tiling over a 12x12 foot outdoor deck that is covered with a porch roof. Live in Atlanta area.

Specs: Flooring is 2x6s
Joists are 2x8x12
Joists are on 16" centers
The joists are attached to the house with a ledger board screwed into the cement foundation.
There are three 4x6s cemented in the ground for the tiers/supports.

How many more tiers/supports do I need to put in? I am thinking that I need to put in footers and cement tiers every four feet along the perimeter and then do the same down the middle. Then use 2x10s attached to the tiers to support the exisitng joists .

Q1: Will this give enough support? Help!!!!!

Q2: Do I need to use both 3/4" plywood and backerboard or just one or the other?

Photos attached.

Thank you for any help you can provide.

Bear B

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09-18-2010, 11:53 AM
First off I don't do outdoor decks, but here are a couple options as it appears your deck structure may not meet deflecto minimums:

EZ Tile:

TI - Proboard system (cant find their minimum structure rqmts on thier site but maybe you can find out more here:


If you don't want to rebuild your deck, you might consider one of the plastic framework systems that suspend standard sized tiles, allowing plenty of deflection and water penetration for good drainage. Other thots?

09-18-2010, 12:24 PM
As I understand this, you already have 4x6 posts every 6 feet along the outer end of the deck. If the rim joist (the one that the other joists are attached to) is 2x8 or better, you have enough support at the edge. You need to add a beam down the center and parallel to the house. It could be a doubled 2x8 and set on 3 posts. That will get your structure suitable for a porcelain tile floor.

The planking you have now is not going to be acceptable by itself. You could install 1/2" plywood, then a system like Schluter's Ditra (see the Ditra handbook by following the link at the right). Look for the "balconies over living space" detail If that adds too much height that you can not get adequate flashing at the doorway, remove the planking and replace with 3/4" plywood, then install the Ditra.

Flashing is very important, even on a covered deck. Also, the deck should also slope away from the house. Often times, these two issues alone are enough to change your plans.

Bear B
09-18-2010, 12:51 PM
Hi Bob,

Thank you for the good advice.

Let me clarify.

The deck - built by the previous owner - only has three 4x6s which are 12 feet from the house and ledger board. One at each corner and one in the middle. There are no supports around the perimeter. This is what worries me. Do you think I need to put in footers and piers every three feet on the perimeter and in the middle to ensure proper support?

Thank you for your guidance.


09-19-2010, 01:31 PM
The joists need support at mid span, so a beam with 3 posts down the middle of the deck is fine. The out-board rim joist needs 3 posts, too. 6 feet apart is fine.