Designed for perimeter drainage of inverted roof and warm roof constructions, the Harmer Modulock straight channel range, manufactured from either stainless steel or galvanised mild steel, is available in 130mm, 200mm and 250mm widths, with either variable of fixed depths.

Two types of Harmer Modulock slot channels are also available - Facade & Terrace. The Facade range is manufactured in either stainless of galvanised steel. The Terrace is manufactured in Stainless Steel only.

Product Images
Key Points


  • A rainwater channel system in three sizes with perforated or closed sides and a choice of 6 grate designs in either stainless steel or galvanised steel
  • Rainwater runoff is collated at hard surface level whilst percolation is relived at membrane level
  • Modulock Channels can be used on podium decks, terraces and balcony areas in conjunction with Harmer Rainwater Outlets and Modulock Pedestal Support systems
  • Can be laid directly on the structural deck or fitted with height adjustable feet
  • A drainage system that intercepts rainwater and improves safety at point of access
  • Compatible with inverted roof, warm roof, green roof and podium deck construction
  • Threshold drainage with the level access requirements of part M
  • Pedestrian Load rated class K3
  • Channel depths can be adjustable or fixed, ranging from 55mm to 150mm
  • Modulock Channels form part of the overall drainage plan for most types of flat roof or deck construction.
  • Buildings are protected from weathering at the venerable point where hard surface meets structure.
  • Channels and gratings are available in Grade 304 stainless steel or galvanised mild steel
  • Available with either a grill or slot grate finish
Installation & Fixing


  • Straight line end to end installation with simple location clips ensures the system is fully stable
  • Factory manufactured or site formed irregular angles accommodate change in direction
  • Modulock channels can be supported directly on the structural deck or supported on height adjusters for raised paving, varying from 50mm to 150mm