F. Ball Subfloor Preparation Brochure - Flipbook - Page 5
01538 361 633 | f-ball.com
WEAK AND
DAMAGED SCREEDS
Poorly installed sand/cement or calcium sulphate screeds
can result in a weak or friable surface which is unsuitable
for the application of subsequent subfloor preparation
products and installation of decorative floor coverings.
A poorly compacted, damaged, or weak screed should be
completely removed by mechanical means and reinstalled
correctly. Alternatively, the surface can be treated with a
surface reinforcement system such as Stopgap SRS which
will quickly penetrate and stabilise the surface of a screed.
Before the application of Stopgap SRS, weak or damaged
screeds should be evaluated by either an In-Situ
Crushing Resistance test (ISCR) or even a subjective
scratch test to evaluate the condition of the subfloor
and to demonstrate its suitability. The surface of the
screed must be exposed, and all laitance and any
previously applied adhesives or smoothing compound
residues must be completely removed. The area should
be vacuumed to remove all dust and debris so as not to
impair adhesion and penetration. Stopgap SRS can be
used over heated floors and damp subfloors but should
not be used on calcium sulphate screeds where the
Relative Humidity is above 85% or over subfloors where
movement is anticipated.
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