I have an old kitchen extension with a concrete floor and I doubt that a damp proof membrane was used. I want to tile it and was wondering what the best way of incorporating damp proofing is. Is there a combination adhesive/damp proof seal out there? I can't build up the floor as it is already a bit higher than the rest of the house.
Are you seeing eveidence of dampness to make you want to put a membrane down. If so lookat Ditra from Schluter.If no obvious dampness you could put a paint on membtrane over the concrete before you tile. Redgard by Custom, sold at HD is one, Goldcoat by Hydroment is another but more expensive (but its expensive for a reason, its good!) Laticrete also makes a good one. All roll on, thin as a dime. The Ditra is about 3/16" or so, but very good to use.