Underfloor Heating Design: Wet vs Dry Systems

Underfloor heating reaches every part of a room evenly, eliminates radiators, and pairs naturally with heat pumps. The choice between wet and dry systems shapes cost, depth, and retrofit feasibility.

Wet (hydronic) UFH

Plastic pipes embedded in screed, fed with warm water from boiler or heat pump.

Strengths

• Lowest running cost (especially with heat pump)
• Most even temperature distribution
• Suits whole-house heating

Weaknesses

• Deep build-up (50–75mm screed plus insulation)
• Slow response time
• Difficult to retrofit without raising floor

Dry (electric) UFH

Electric heating cables or mats laid under floor finish.

Strengths

• Shallow build-up (5–15mm with mats)
• Fast response
• Easy retrofit in bathrooms or kitchens
• Lower install cost

Weaknesses

• High running cost (electricity ~3–4× gas per kWh)
• Not suitable for whole-house primary heating
• Limited compatibility with renewables

Retrofit options

Slim wet systems

Specialist 15–20mm build-up wet UFH for retrofit — overlay over existing floor, then new finish. Suits ground floor remodels.

Between-joist wet

Pipes routed in spreader plates between existing joists. Lower output than screed systems but workable for retrofit.

Electric mat retrofit

5mm mats under tile or LVT finishes — standard for retrofit bathrooms.

Cost

• Wet UFH (new build, ground floor): R1,500–R2,800 per m²
• Wet UFH retrofit (slim system): R2,800–R4,400 per m²
• Electric UFH: R1,600–R3,200 per m²
• Manifold and controls: R12,000–R36,000 per zone

Floor finishes

• Tile and stone: optimal (high conductivity)
• Engineered wood: good (rated for UFH)
• Carpet: degraded performance (insulating)
• Solid wood: risk of warping unless rated

MCFAR integrates UFH with heating systems on residential projects.

Frequently Asked Questions