As my role as a flooring expert I come across floors that have been fitted on top of Asphelt.

Asphelt is a coating that was used frequently up until the mid-1970’s.

It usually has a dual purpose.

  • Acts as a damp-proof membrane
  • Is a surface that could be lived on and used as a finished floor.

Usually 19mm approximately thick, it was applied as a liquid that is applied over tar paper. It sets and goes hard.

Like glass, despite appearing to be solid, it remains a liquid.

The problems occur usually when something that is not dimensionally stable is adhered to it.

As a wood flooring inspector or wood flooring expert witness, it is not surprising that the floor covering is often wood.

The symptom is that the once flat wooden floor, has swollen up and now resembles an alpine mogul field.


I usually cut a test hole to reveal that the wood is bonded well to the asphalt, but the asphalt has lifted off the cementitious base.

Wood when exposed to changes in the environment that it has or is living in will either shrink when its moisture content diminishes or will expand as it increases.

The asphalt being bonded to the floor expands with it. The asphalt being laid with no expansion space at the perimeter has nowhere to expand into, pushes up.

If requested as a wood flooring expert to write a specification, I recommend that it is lifted, and the sub-floor then prepared with modern liquid damp proof membranes and smoothing compounds before the acclimatised flooring of choice is laid.

My advice if you are considering covering your asphalt floor is to contact a wood floor expert  or wood floor inspector who will I am sure, be only to pleased to recommend a course of action to avoid a costly mistake being made.