Dry Fix GRP Valley Troughs

Mortar-less roof drainage dry valley systems. Provides quicker, safer and simpler installation processes compared to traditional wet fix and lead material alternatives.

Fire-rated to BS 476 Part 3 – SAB and BS 476 Part 7 Class 3 and compliant with NFRC Technical Bulletin – 28.


  • Valley troughs provide a weatherproof drainage channel where there are changes in direction or material in the roof structure
  • Suitable for:
    • concrete or clay roof tiles
    • natural and man-made roof slates 
  • On roof pitches up to 60° 
  • Featuring a 110mm up-stand to suit natural or manmade slate and concreate and clay roof tiles

Product Information

Roofline Dry Fix GRP Valley Troughs

DescriptionDimensions (w x l)Up Stand HeightProduct Code
Dry fix GRP universal valley trough for slate and tile*400 x 3000mm110mm88106

*Supplied with flexible self-adhesive packers

  • Robust and cost effective material with no scrap or resale value
  • Maintenance free, light and easy to handle and cut 
  • Substantially quicker installation time than mortar based process 
  • Adequate flexibility for roof pitch variation
  • Can be installed in virtually all weather conditions 
  • UV inhibiting film restricts mould and fungal growth 
  • Fully flexible closers material enables precise fitting to troughs and other roof materials 
  • Valley troughs supplied in 3m lengths
  • Complies with the NFRC Technical Bulletin – 28 
  • Satisfies NHBC requirements 
  • BBA Approved 
  • Fire rated to BS 476 part 3 – SAB & BS 476 part 7 Class 3
  • Glass reinforced polyester. ‘Lead’ grey colour.
  • Valley boards must be installed to support the valley trough. This is a requirement of the NHBC Standards.
  • The underlay material and battens should be fixed in accordance with the standard roofing best practice; with a batten running the length of the valley on each side to accommodate the dry fix valley trough’s water bar section.
  • The valley troughs are fitted onto the valley boards and should be firmly fixed from the eaves closure section upwards using suitable large headed roofing nails on either side.
  • All overlap troughs should be at least 150mm when measured in the vertical. Care should be taken to ensure than the central raised section is positioned central to the valley.
  • If the valley trough finishes at a ridge with a corresponding valley, the head closer units can be used.
  • The head closer must overlap both valleys troughs by 150mm and form a neat waterproof seal.
  • Tiles or slates being laid into and over the troughs should be laid in accordance with the manufacturer’s recommendations.
  • When the slating or tiling has been completed, the eaves closer unit should be cut with a sharp knife or scissors to allow water discharge into the rainwater gutter.
  • It is important to ensure that the valley troughs are cleared of any debris on completion to ensure that water flow is not impeded.
  • The installation of GRP valley troughs and roof slating or tiling must be carried out in accordance with all relevant British Standard clauses.
  • Measure the valley length up the slope and divide by 3 (product length) to determine the quantity of dry fix GRP valley troughs required.
  • Allow a minimum vertical overlap of 150mm lap if it’s necessary to join valley rough sections together.

Latest News