SMET screed boosts heating at Cork passive house

Our liquid screed installed three years ago at a passive house in Cork City has been performing superbly, according to its architect, enabling the A1 rated home to be heated quickly and evenly via underfloor heating when required.

Designed by Wain Morehead Architects, the Wayside passive house was finished in 2016. It was built from externally insulated blockwork and featured a solid oak floor with 50mm Alpha Hemihydrate screed, fitted by Smet Supported Partner, Fast Floor Screed Ltd, with insulation below, all resting on a raft foundation.

The screed was poured onto underfloor heating pipes that distribute heat from a Nilan combined heat pump & ventilation system. Architect John Morehead told Passive House Plus that, when he returned to the house recently with a thermal imaging camera, he was hugely impressed both at how quickly the floor heated up, and how even the distribution of heat in the floor appeared to be.

“It seemed to have an incredibly quick response time,” Morehead said. “I didn’t expect it to be that quick.” He also said that the warm temperature seemed to be very evenly distributed over the whole floor. “It’s quite a thin floor, and it’s on a whack of insulation, so one would expect it to be responsive — but credit where credit’s due, it seemed very responsive.”

The screed was mixed and poured on-site by Fast Floor Screed Ltd using the CASEA Südanit 280 Alpha Hemihydrate binder from SMET Building Products. The screed was poured to a depth of 50mm, fully encapsulating the underfloor heating pipes.

A self-compacting, self-flowing, self-levelling screed like Südanit 280 Alpha flows to fully encapsulate underfloor pipes or wires and reduces the potential for air bubbles/pockets which can have an adverse effect on heat transfer. It also allows underfloor heating to be commissioned and running during screed application, to enable fast drying, up to a maximum manifold water temperature of 25C.

For more see Passive House Plus magazine.