Pete's Tiling over Concrete Patio

[SSK]

My mom said she got an installation only quote to do her enclosed patio of 200 square feet, for 4,000 dollars. This was a contractor who did previous work on the house. I told her to tell them to *!@# off. 20 bucks a square foot and no cuts! I assume they did not want the job. This is a ground level job in the summer, and I would assume that maybe 1500 would be in the ballpark. So I told her I would do it for her. I have never done a tile over concrete, but I am confident I tile as well as most guys who do this for a living. Just a lot slower. I have spent a lot of time on this site and have learned a lot. I have done a few bathrooms and other floors, but is there anything unique I need to worry about for tiling over concrete in a space that is not temperature regulated. Here is the room


Do I need any isolation membrane or can I just use a good modified thinset directly on the concrete? The plan would be 18x18 or 12&24 The surface is crack free and in excellent condition. Would you grout up to the walls or use a caulk?

Also how would you recommend finishing this off at the doorways. Currently there is nice brickwork at the doorway, but maybe that gets covered up. I could do some kind of Schluter transition to either keep the brick or go to the end of the brick.

Any advice would be appreciated. Thanks.

[CountryBumkin]

Pete, is that patio area subject to freezing?
Also how old is the concrete?
If you tile directly over the patio concrete any settling/cracking of the concrete will transmit through the tile. That is where/why an isolation membrane is used. There are "flexible" mortars available too that allow a little movement without cracking, but not as good as an isolation membrane.
You are supposed to use caulk in the transition (from floor to wall) joints since this is where the minor movements occur first.
There are "bullnose" tiles that could be used at the door openings - but that would make the brick tile lower than the new tile (will hold dirt/water). I would tile over it to keep finished floor the same height.
Make sure the tile you use has a high COF (slip resistance) if the area is also subject to getting wet.

[Davy]

You say the concrete is in excellent condition. But is it flat? It will need to be with large tiles like you are installing.