Rugs & Underfloor Heating: What You Need to Know

Underfloor heating (UFH) is a brilliant way to warm your home evenly and efficiently — especially in open-plan spaces. But if you're adding a rug, it's essential to choose one that works with your heating system, not against it.

At Rugs Direct, we help you find rugs that feel great underfoot and keep your heating system running smoothly.

🔍 What Is a TOG Rating?

A TOG rating measures how much heat a material traps — originally used for duvets, but now a useful guide for rugs too.

• Low TOG = better heat transfer
• High TOG = more insulation, less heat flow

For underfloor heating, the combined TOG of rug + underlay should not exceed 2.5. Ideally, your rug alone should be between 0.5 and 1.5 TOG.

⚠️ Flooring Matters Too

Some flooring types — especially wood and engineered timber — have temperature limits (typically around 27°C). Rugs can trap heat and create “hot spots,” leading to warping, swelling, or delamination.

• Tile and stone floors are more heat-tolerant and ideal for rugs.
• Wood floors require extra care: choose thin, breathable rugs and avoid placing them in direct sunlight.

🧮 Approximate TOG Estimation Logic

You can build a scoring system using this formula-style logic:

Estimated TOG = Base + Material Factor + Pile Factor + Backing Factor + Density Factor

Where:

• Base = 0.5 (starting point for thin synthetic rugs)
• Material Factor:
• Polypropylene, viscose, cotton: +0.2
• Wool: +0.5
• Mixed synthetics: +0.3
• Pile Factor:
• < 8 mm: +0.1
• 8–15 mm: +0.3
• 15 mm: +0.6
• >25mm: +1.0

• Backing Factor: +0.25
• Density Factor:
• Lightweight weave: +0.1
• Medium: +0.3
• Heavy/tufted: +0.5

In its simplest terms, rugs with a pile height under 15mm should be fine. Those called shaggy and over 25mm should be avoided if you are worried about UFH, especially on a wooden floor.