In this issue, Phil Nightingale advises on working over underfloor heating in a kitchen where floor-to-ceiling windows would subject the floor to solar gain and extreme temperatures.
Flooring installations where underfloor heating is present are frequently a source of questions that we receive from flooring contractors.
I recently provided site support on a project where the contractor needed to encapsulate a water-based underfloor heating system, with the pipes snaking around a plastic tray that was affixed to the subfloor, prior to the installation of vinyl planks in a newly fitted domestic kitchen.
The kitchen units had been set to a height that meant that the floor level would have to be raised up 20-30mm above the tray. Regardless, it’s advisable to allow at least 15mm of a levelling compound above the pipes to avoid hotspots, which could affect the LVT floorcoverings.
Floor-to-ceiling windows in the kitchen also meant the potential for solar gain to result in extreme temperatures and temperature fluctuations, which can cause vinyl floorcoverings to expand and contract and lead to unsightly tenting in vinyl planks and gapping at the edges over time.
Kitchen efficiency
Most floor levelling compounds can be applied at thicknesses up to 20mm, meaning at least two applications would have required to build up the necessary thickness. This would have been time consuming, necessitating multiple drying times and priming between layers.
Instead, we recommended using F. Ball’s Stopgap 600 Base, which is designed to be applied at thicknesses up to 50mm, allowing contractors to raise floor levels quickly and easily. The subfloor was first primed using F. Ball’s Stopgap P141 primer, chosen because it creates a textured finish to enhance bond performance between levelling compounds and non-absorbent surfaces, which include those of the plastic tray and piping. It is particularly recommended where levelling compounds will be applied at thicknesses greater than 20mm as the strong bond created when using Stopgap P141 is better able to withstand the increased stress that thicker depths of levelling compound exert when drying.
Subsequent steps
Once set, Stopgap 600 Base must be capped with a minimum 3mm of Stopgap 200, 300 HD, 800 or 1200 Pro – the selection should be determined by the performance characteristics required. In this case, Stopgap 300 HD was specified because its high compressive strength and excellent self-levelling properties provide a perfectly smooth base for LVTs in order to optimise the appearance of the finished installation.
Before Stopgap 300 HD was applied, it was again necessary to prime the surface using F. Ball’s Stopgap P131 general-purpose primer, diluted with four parts water to one part primer.
Adhesive recommendation
Finally, we recommended installing the vinyl planks using F. Ball’s Styccobond F49 Hybrid PS temperature tolerant, pressure sensitive vinyl adhesive.
The solvent-free, water-based adhesive provides the advantages of a pressure sensitive adhesive, including high initial tack, helping to position the floorcoverings as required, while developing the ultra-high bond strength to withstand extreme temperatures and temperature fluctuations expected as a result of the kitchen being heavily glazed. Once set, the adhesive holds floorcoverings firmly in place when exposed to temperature fluctuations from -20°C up to +60°C.
The extremely strong bond formed by this adhesive is also water resistant, making it ideal for use in areas that will likely be subject to moisture, including as a result of spills and wet cleaning methods that floorcoverings are likely to be exposed to in a kitchen environment.
One important thing to remember when undertaking flooring installations where underfloor heating is present is that systems must be turned off during and at least 48 hours before and after the application of subfloor preparation products and adhesives.
Phil Nightingale is F. Ball technical representative for the East Midlands.
F. Ball’s regional technical representatives provide advice to flooring contractors on how to get the most out of F. Ball products, including conducting site visits and producing case-specific reports advising on the best course of action for particular flooring projects. Find out who your technical representative is here.