Heat striping refers to visible bands or uneven temperature zones across the surface of a concrete floor with underfloor heating (UFH). These stripes often appear where the pipes are closest to the surface or spaced too far apart. Striping not only looks poor, especially on polished floors, but also indicates inefficient thermal output. This guide explains how to avoid heat striping during UFH slab design, installation, and finishing.
Pipe spacing should match the room’s heat demand and slab design. For concrete floors with exposed finishes, 100 mm spacing is often preferred to create uniform heat distribution. Wider spacing, such as 200 mm, is acceptable in low-demand zones but may create temperature banding in large open areas. Always base layout on a heat loss calculation — don’t guess. Closer spacing is particularly important in high-ceiling spaces or where thermal comfort at floor level is a key design goal.
Ensure the concrete covers the UFH pipes consistently across the entire slab. The recommended cover is typically 50 to 75 mm above the pipes. If some sections have only 30 mm while others have 80 mm, temperature variation will show as thermal striping. Use screed rails, depth gauges, and lasers to verify consistent slab depth during the pour. Avoid floating pipes or high spots caused by poor fixing or mesh shifting during placement.
Heat striping is often amplified when the floor lacks proper insulation. Use high-density PIR or XPS boards below the slab and edge insulation around all walls. Poorly insulated edges and corners create cold zones that distort heat distribution. Ensure boards are tightly joined, with no gaps, and perimeter insulation is installed full depth. If the slab is thermally inconsistent, heat will travel unevenly, causing visible or measurable temperature lines at the surface.
Never activate the UFH system before the slab has cured. Early heat causes rapid drying along pipe runs, while other areas stay damp, leading to permanent discolouration and surface warping. Wait at least 28 days before switching on the system, then raise the temperature gradually over several days. Striping caused by early heating is often permanent and most visible in polished or exposed concrete finishes.
For slabs that will be polished or left exposed, a self-levelling overlay or tight power-floated finish helps reduce surface imperfections that highlight heat bands. Any surface variation will cause uneven heat transfer, especially on thin slabs. Polished floors with slight undulations can show ghosting of pipe runs even if the heating system is performing properly. Flatten the surface consistently and test it with a laser or straightedge before finishing.
Once the slab is fully cured, bring the heating system online using a temperature ramp-up schedule. Start with low flow temperatures (e.g. 20°C), then increase by 2 to 3°C each day. Sudden thermal expansion from full heat can highlight any weak areas in curing, create stripe patterns in the floor surface, or affect finishes like sealers or polish. Always follow the heating protocol provided by the UFH supplier and ensure the slab is monitored during early activation.
If you'd rather skip the stress and get a flawless concrete floor polished by professionals, we’ve got you covered. From precision prep to polished perfection — we handle it all.
Get in touch today for a no-obligation quote on polished concrete flooring:
Or fill in the form below and we’ll get back to you with honest advice and a competitive quote.