Tiling mavens, give me your last minute tips (outdoor retaining wall)

In My Humble Opinion
1

I have an ugly concrete-block retaining wall outside, 5’ tall, that I want to tile. My back yard is terraced, so this wall is holding the dirt in the upper level in. Also, the surface at the bottom of the wall is garden, i.e. dirt. I appreciate any advice, especially advice that derives from experience. Here is where my plans are now:

12x12 porcelain tiles, 8 mm thick. Same tiles throughout. (Tiles have varied natural-looking color patterns something like natural stone.) Running bond pattern.

Will be cleaning the wall thoroughly before tiling. Suggestions? Currently looking at Krud Kutter or Rustoleum Restore.

Using metal edging rather than bull-nose (can’t afford enough bull-nose tiles for project, and the bull-nose that goes with the tile I’m getting isn’t very good anyway)

Need to use exterior grade thin-set mortar. Need to put thin-set on wall and also on backs of tiles (to make sure tiles stick well to walls with some minor irregularities)

Need to establish support to keep the bottom row of tiles straight; I thought I would use a line of the metal edging which has the advantage that it could stay there permanently. Once the bottom tile row has dried, that should be enough to support the 4 rows above it, right?

Expecting to use 3/16" grout lines. Sanded grout; haven’t checked yet if special exterior grout is needed. Choosing a grout color for blending rather than contrast.

There is a stairway in the middle of the wall; I will be tiling the sides of this stairway to match, but leaving the steps themselves alone (nice rustic old bricks). For the fussy cuts around the steps I will need a wet saw; I expect the other cuts will all be straight cuts, so I can use a tile cutter. Foolish or OK? Because of the running bond pattern, some of these straight cuts will be up against the edging by the stairway.

I have tiled before, indoors, so I am familiar with most of the tools and routine of tiling. But this is a big job that may take several days. Does the weather matter (cloudy vs. sunny, barring rain of course)?

2

Definitely use a tile saw. Even the little one I have works fine and makes it easy. Check into glue, there are stone glues available, it’s tough to keep them on stone with any kind of cement. Definitely use thin-set to get a smooth surface for the tiles though. The metal edge is a good idea. I only tried something like this once, the tiles were heavy, actually floor tiles, but most of them stayed up. Good luck with this.

3

So you’re suggesting using a skim coat of cement to smooth the surface, then use glue to hold the tiles? I think I’d be afraid of the skim coat breaking free. The tiles I have chosen are multi-purpose, either floor or wall tiles.

4

In New England we rarely do that kind of exterior tile, though it would be fun. My first thought is to make sure you have a nice cap material with an overhang. Here we might use bluestone, and consider even cutting a kerf as a drip-edge if it was not too much hassle. Keeping water out of the wall assembly is key to durability.

Think about concrete backer units on the wall. As long as they are properly mechanically fastened and backbuttered, it will make applying the tile way easier.

As always, getting your reference/base course level and laid out properly is important. It’s not wrong to spend all day setting and supporting that one course, and letting it dry a couple of days so it is absolutely fixed and won’t creep and cause wandering joint lines.

A really good reference site is the John Bridge ceramic tile forums. The professionals are pretty willing to help out homeowners who are respectful and do their homework first. I’ve laid a ton of tile in my time, but now my construction biz is a sideline only, so I use that site to keep up to date. I did a bathroom last summer with Ditra system floor heat under the tile, and I was able to research all my details there on using some of the latest technology (it came out wicked good and the clients love it).

http://www.johnbridge.com/vbulletin/showthread.php?t=14730

5

In New England, I’d be concerned that water might seep behind the tiles, and then the freeze-thaw cycle would loosen them. But the OP is in San Francisco, so that should not be a problem. But has the OP thought about a stucco job on the wall? That might be easier, even if you have to bring in a contractor to do the work.

6

Yup. First thing that came to my mind was - tile saw. And you must cap it somehow. Also, I would pressure wash the concrete blocks first to remove crumbly stuff.

And I would get a bit whimsical with colors and patterns.

7

I appreciate the suggestions for capstones, and I had considered that, but capstones are expensive, and the total length is 38 feet. They are also heavy (if I didn’t mention it, the only way to the backyard is through the house and down two flights of stairs). My plan was just to put the same tile on the top as on the sides, with that top tile and the edging covering the top edge of the wall tile. Maybe there’s a way to further waterproof the top, but I assumed that exterior grade thin-set would be enough. I will check out the suggested forum. And I will go and price actual capstones to be sure if they are out of my reach.

I also appreciate the suggestion for a stucco job. I haven’t priced such a job (I would certainly have to hire someone to do that) except for an online estimator which scared me right off. As I mentioned in the OP, I had considered putting on a skim coat of cement, and painting that. But I think the tiles will be more durable and better looking, assuming I don’t have a problem with them falling off.

I am looking to do this on as cheap a budget as possible and still get a good result. I expect to spend about $450 for the tile, $100 for the edging, $30-$60 for the thin-set (not sure how far it will go per bag), plus grout, concrete cleaner, and miscellaneous. I think I already have all the tools. My time is free.