Do we need a liquid Dpm on a concrete floor with old bitumin on it?

Hi, I would suggest you apply 2 coats of aluminium oxide primer, before latexing the floor. The Primer will form a barrier between your carpets and the bitumen (which might stain your carpet if you were to spill something hot such as tea) The Latex will level the surface to provide an excellent surface finish. Regards Simon

I have a similar floor in my house and the bitumen is supposed to be acting as the dpm. Its old and brittle now and nothing wants to stick to it. The only solution I came up with was using a sheet dpm such as is fitted under a laminate floor and laying that down first before the carpet. Not everything in building is an exact science especially when it comes to older products and styles of construction. There are also some underlays with a rubber back and even some stick down underlays for this kind of issue. Research your local suppliers.

Hi. The black layer is possibly the adhesive from the previous floor such as thermo plastic tiles or parquet. First scrape up as much of the residue as possible apply a cote of Ardex NA then the liquid Dpm and then another layer of Ardex NA. Tried and tested and it works. Getting someone to do a damp test to find out the relative humidity RH% of the slab might be a good idea with a house of this age. David

In this day and age best to take the old dmp up as evolution and technology moves on. There are several products out there (some mentioned above) that are straight forward and easy to lay. That way if you are having a nice new floor ie tiles, karndean,etc, then you don't want the dpm to breakdown. Especially if its breaking down already as I am nearly as old, and I am.