Page 94 - CFJ_Dec25

ADVICE & INFORMATION

Chris McQuade
Flooring failure fix

Chris shares how F Ball’s technical team resolved a real flooring
failure caused by poor moisture control, offering practical guidance

N F Ball technical representative work had applied a waterproof surface compound and bitumen DPM. The
Arecently supported a flooring membrane over the newly installed flooring contractors who sought our
contractor who’d been called to a concrete screed, followed by a thin layer guidance could then use F Ball products
Victorian residential property where of smoothing compound to create a to install new wood floorcoverings.
timber flooring that had been installed smooth base for floorcoverings. The age Following this, they applied F Ball’s
in a ground floor extension had begun to of the property meant there would’ve Stopgap F77, which creates a barrier
warp and lift – it looked like waves on the been no legal requirement for a damp- against excess subfloor moisture where
sea. proof course to be installed when it was subfloor relative humidity levels are up to
Damp seemed the obvious cause built. 98% with a single coat application.
– it’s still the leading cause of floor So the problem couldn’t be damp? Well, Reinstalling the base
failure. Where subfloor relative humidity the tech rep suspected that the solution Once the membrane had cured, the
levels are above 75% (or 65% where in place was actually a bitumen damp- surface was primed using Stopgap P141,
wood floorcoverings will be installed), proof membrane. When they contacted which is specially formulated to enhance
a moisture management solution is the builder to check, this was confirmed. the bond performance between non-
absolutely essential to stop moisture The issue absorbent surfaces, including waterproof
attacking floorcoverings and adhesives. The problem is that these types of surface membranes, and subsequently
Closer inspection products are sandwich membranes, applied subfloor preparation products. It
To be sure, they lifted some of the which unlike epoxy/resin systems, such contains recycled uPVC pulver to create a
floorcoverings to inspect the subfloor. The as F. Ball’s Stopgap F77, or water-based textured finish, which helps adhesion.
builder who’d undertaken the preparation types, such as Stopgap F78, don’t form To create the perfect base for the
a rigid film when new wood floorcoverings, it was
cured. Instead they recommended that contractors applied
remain soft and
flexible. This isn’t Stopgap 300 heavy-duty smoothing
an issue if a thick, compound. Its high compressive strength
structural screed is creates a durable surface, which is
applied over the top. important if floors are going to be subject
However, if a thin to heavy loads or high levels of foot
layer of smoothing traffic.
compound is It’s also better able to withstand
applied, the stresses stresses exerted by the natural
the bitumen damp- movement of wood. Its excellent
proof membrane self-smoothing properties ensure
(DPM) will be a completely smooth base for
subject to, can floorcoverings.
cause it to separate, Full circle
compromising Finally, the contractors used
its integrity and Styccobond B95, a flexible wood
allowing subfloor adhesive, to install new wooden blocks
moisture to migrate in a herringbone pattern. The single-
to the level of part, moisture-curing adhesive will
floorcoverings and accommodate the natural movement
cause problems. of wood throughout the lifetime of the
The solution installation. It also offers good initial grab,
In this situation, useful for creating the parquet design.
there was no other Using these products in this order
option but to lift all will ensure a long-lasting professional
of the floorcoverings flooring finish, with no risk of floor failure
and mechanically as the result of excess subfloor moisture
remove the this time. 
previously installed Chris McQuade is a technical service officer,
smoothing F Ball and Co

94 CFJ December 2025 www.contractflooringjournal.co.uk
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