Downsend School, Leatherhead

About this project

When Downsend School installed new supply and extract ductwork across its rooftop, SR Thermal Services Ltd was brought in to insulate and weatherproof the whole run. Ductwork sitting out in the open at roof level takes everything the British weather throws at it - rain, wind, frost and constant temperature swings - so getting both the insulation and the outer finish right matters just as much for the building running costs as it does for how long the system lasts. We insulated the supply and extract runs with 40 mm Kingspan board and finished them in grey ProClad, a tough weather-resistant outer skin that keeps moisture out and gives the whole rooftop a clean, uniform line. Every board joint was sealed with 4-inch jointing tape and worked carefully around the bends, branches, transitions and plant connections, so the insulation stays continuous with no cold gaps left to leak heat. To keep the edges crisp and protected, we fitted 50 mm aluminium stucco angle to the exposed corners, and 40 mm angle around the access doors so the panels can still be opened for future inspection and cleaning. Supply ducts were marked with red and blue ID triangles and extract ducts with grey, so anyone servicing the system later can read the roof at a glance. The finished result is a rooftop duct network that holds its temperature, shrugs off the weather and keeps performing year after year.

Scope of works

• External rooftop ductwork insulation
• ProClad weatherproof cladding
• Supply & extract duct insulation

Materials & systems

• 40mm Kingspan insulation board
• Grey ProClad cladding
• 50mm & 40mm aluminium stucco angle
• 4-inch jointing tape
• Service ID markers

Completed works

Tap any photo to view it full size.