When Dundee & Angus College recently underwent a refurbishment of its student social space and catering facilities to enhance its offering to students, it was Bostik’s subfloor preparation products and technical advice that enabled the installation of the floor coverings.
The 20,000m2 college at the Kingsway Campus in Dundee first opened in 1963, and is one of the largest in Scotland, with around 12,000 enrolments. Westend Flooring Specialists was appointed to install the flooring and turned to Bostik for its specialist input and advice.
A challenging subfloor
Bostik’s technical team visited the site in the early stages of the refurbishment to inspect the subfloors ahead of putting together a report recommending how Westend Flooring Specialists could best install the flooring. This inspection revealed several challenges across different areas of the subfloor.
Some areas of the subfloor exhibited straight-line cracks, indicating day joints opening and closing due to moisture differentials in the substrate. As this could potentially compromise the bond of the finished flooring, the Bostik team recommended that the flooring contractor returned the subfloor to a sound concrete base and then rake out the cracks to make them dust-free.
Elsewhere on the subfloor, there was a hard, dense blue material present. The Bostik team identified this as a surface DPM left over from a previous refurbishment. Concerned as to its efficacy, Bostik advised that Westend Flooring Specialists mechanically abrade its surface to remove all contaminants.
Other areas of the subfloor were made of quarry tiles. Together with the age of the building, this suggested that these areas were unlikely to have a damp-proof membrane (DPM) beneath them. Bostik therefore recommended that the quarry tiles were removed along with any old smoothing compound present.
Finally, some sections featured poorly bonded smoothing compound, while others consisted of boarded timber. In both cases, Bostik’s technical team again advised that these should be removed to create a sound base from which the flooring contractor could work.
The ideal products
Once these issues had been addressed, Bostik suggested that – in the areas of the subfloor that were not direct-to-earth – Westend Flooring Specialists apply the solvent-free HYTEC E570 ONE COAT surface DPM to suppress any residual moisture. The product contains the exact quantities of resin and hardener for mixing together, and can provide protection up to a maximum hygrometer reading of 97 percent relative humidity (RH).
On the straight-line cracks, the team advised that the DPM be bulked out with clean, sharp sand on the wider joints, while on the quarry tiles they recommended that the DPM be applied at a reduced coverage rate, with special attention on ensuring that the grout lines were filled in.
The next step was for Westend Flooring Specialists to apply Bostik’s GRIP A526 UNIVERSAL PRIMER. A water-based, solvent-free acrylic dispersion primer and bonding agent, GRIP A526 UNIVERSAL PRIMER provides excellent coverage rates and dries within one hour in good conditions, making it ideal for fast-track installations.
Then the flooring contractor used Bostik SCREEDMASTER SL C540 FLOW, the company’s two-part smoothing compound with improved workability for smoothing uneven floors. The high flow, easy trowelling compound created a smooth surface on which to lay the floor coverings.
“Bostik were great to deal with,” comments Anthony Kierans at Westend Flooring Specialists. “They visited the site several times to carry out their initial site survey and check on progress, and on each occasion their input was extremely helpful and much appreciated. The cracks in parts of the subfloor were a real challenge, for example, but Bostik’s advice and epoxy DPM worked a treat. All the Bostik products worked brilliantly, and we had some great feedback from our fitters.”