This is a question that is often asked, and the answer largely depends on how old the parquet floor is and how it was installed.
The problem with parquet
Parquet wood block floors have been installed in homes since the mid 1800’s. A popular option for fixing the parquet wood blocks onto concrete sub-floors was with the use of bitumen adhesive. This had the added benefit of preventing moisture rising up through the concrete and warping the wood. The problem with bitumen, however, was that it perished over time and lost its strength as an adhesive and moisture barrier.
Wood, being a porous material, will often allow low levels of moisture to pass with little or no obvious signs that anything is wrong. The result is that old parquet wood floors often appear dry and in good order, when in fact a problem is brewing.
When a wood or vinyl floor is installed on top of old parquet, you’re essentially putting a lid on a simmering pan. The moisture rising through the parquet becomes trapped beneath the laminate or vinyl layer, causing the parquet blocks to expand and erupt upward, creating an effect known as tenting.
This tenting will push the new wood or vinyl floor upwards, warping the new floor and requiring removal.
In some cases the moisture can affect the laminate flooring itself, causing the laminate to expand excessively – leading to a costly repair or replacement.
Another way the problem can manifest is through a slow rot that doesn’t immediately result in tenting and any visible signs of something being wrong. All you’re aware of is a damp, musty smell that you cannot get rid of as the parquet slowly moulders underneath your beautiful new floor.
So to sum up – if the parquet is old and is stuck down with bitumen, rather don’t take the risk of installing anything over it. Lift the parquet and let the flooring installers provide proper damp insulation over the concrete.