John Guest Underfloor spreader plates (from below) are an underfloor heating (UFH) pipe fixing system designed for use with traditional timber suspended or pre-engineered joists. There are pipes fitted under the floor, so there is no height build up. The 15 mm pipe is installed into single grooved aluminium spreader plates that transmit heat evenly across the floor. A layer of insulation is placed in the void below the plates to minimise downward heat loss. It is ideal for new builds, extensions and renovations, especially at first floor levels.