Self Levelling Concrete DPM or not?

Hi There, Newbie Question....

I am currently in the process of renovating my porch. While doing so I noticed that the concrete floor was moving. After some investigation work I decided to pull it up. It turned out that it was a concrete pad about 25mm thick sitting on the original concrete floor. This pad came up with some ease, but has unfortunately now left the porch floor somewhat lower than the hallway floor. My plan is to pour some self levelling concrete in to bring the floor level back up. I know i need to key the original pad I guess with PVA or a bonding solution of some sorts, but my question is, should there be a DPM put down first and the the concrete or can I put the DPM down afterwards before I lay flooring?

I will add that the house was built in the sixties and the porch used to be just a roof with a pole in one corner.



So I have no idea if it has a DPM under the original pad or not. My plan was to use one of those paint on DPM after I had relaid the floor?

Many Thanks

I doubt if an open porch would have a DPC. Why would you want to put one it? How is the old level with respect to the door step?, should go under it. Do you really want a concrete porch floor?, only virtue is non slip and cheap. Why not go for some tiles (external frost proof and nonslip).
Frank

Sorry, don't think I made it clear. The porch used to be an open porch, but it is now an enclosed one. Had been for some fifteen years. The level of the porch floor is some 25mm lower than the internal floor, which is why I need to level it to bring it level. The floor will be one run of flooring from front door through hallway through kitchen to back door. So I was checking to see if I need to put a dpm in as I don't want any damp rising into the flooring.

The DPC in the floor and walls of the porch should be lapped into the houses DPC. Do the walls show any sign of rising damp?, if they do not then its fair to presume that somewhere under the concrete there is a DPC. Else you put a DPC under the floor bit and the walls will get damp.
Frank

Coat it with some liquid membrane or bitumen type sealer.

You do realise that you'll need special high-build self-leveller, which has an even higher cost?