Skip to Content

Rainwater FAQs

Rainwater FAQ Banner

Downpipes should be fixed at every 2 metre distance or less.

Yes, or to a gradient of 1:600.

Yes, angles can be made to measure. Please contact our technical department.

 Roundstyle Squarestyle Deepstyle Prostyle
 112mm 114mm 115mm 106mm
FloplastYes No No No
HepworthYes No No No
HunterYes Yes* No No
MarleyYes No Yes** No
OsmaYes No Yes No
PolypipeYes No Yes*** No
TerrianYes No No No

*Brett Martin gutter will fit to Hunter square fittings if 3mm (approx) is trimmed off each side of the insertion depth of the gutter.

** Brett Martin gutter will fit to Marley Deepflow fittings if 3mm (approx) is trimmed off the insertion depth of the gutter. Brett Martin Deepstyle fittings will fit to the top edge of Marley Deepflow gutter.

*** Brett Martin Deepstyle gutter will fit Polypipe fittings if 3mm (approx) is trimmed off each side of the insertion depth of the gutter.

gutter 1Thermal movement allowance, when each length of gutter has been snapped into position check that each end is not inserted into the fitting beyond the ‘EXPANSION ALLOWANCE’ line. This allows the gutter to move with changes in temperature without distortion.

There are several options you can choose from -

gutter 2

In domestic applications where the 68mm round and 65mm square downpipes are used, they commonly discharge through a shoe into the hopper of a gully.







gutter 3 Alternatively the rainwater can discharge into a back inlet gully through an adaptor and bend.







gutter 4

is possible to connect the 110mm downpipe directly to a PVC underground drainage system: where this is  of greater diameter an adaptor can be used.








Adaptors are also available to connect Rainwater downpipes to underground drainage systems of other materials.

106mm Prostyle gutter system

1:600 FallOutlet @ CentreOutlet @ End
Flow Capacity5.1 l/sec2.55 l/sec
Max Roof Area242m²121m²


112mm Roundstyle gutter system

1:600 Fall Outlet @ Centre Outlet @ End
Flow Capacity 2.43 l/sec 1.31 l/sec
Max Roof Area 116m² 62m²


114mm Squarestyle gutter system

1:600 Fall Outlet @ Centre Outlet @ End
Flow Capacity 3.03 l/sec 1.52 l/sec
Max Roof Area 144m² 72m²


115mm Deepstyle gutter system

1:600 Fall Outlet @ Centre Outlet @ End
Flow Capacity 4.58 l/sec 2.31 l/sec
Max Roof Area 220m² 110m²


170mm Deepstyle gutter system

1:600 Fall Outlet @ Centre Outlet @ End
Flow Capacity 10.24 l/sec 5.12 l/sec
Max Roof Area 488m² 244m²

Brett Martin offers two kinds off gutter protection systems.

The first is the Gutter Protection System (GPS1) which sits in the top of the gutter under the bracket and union clips. This system is not suitable for use with the 106mm Prostyle and 170mm Deepstyle gutter systems.

The second option is Porcupipe Bristle Gutter Protector (BRP16CI) which comes in 2m lengths and is inserted between the gutter and the roof tiles.

All products are manufactured to existing British and/or European standards. 

Brett Martin’s Rainwater systems are covered by our Guarantee.

Downpipes are available in:

  • 65mm Square for 106mm Prostyle & 114mm Squarestyle Gutter System
  • 68mm Round for 106mm Prostyle, 112mm Roundstyle and 115mm Deepstyle Gutter Systems
  • 100mm x 75mm Rectangular (cast iron style only)
  • 105mm Round (cast iron style only) for Cascade High Capacity Gutter System
  • 110mm Round for Deepstyle 170mm Gutter System
  • 160mm Round
  • 200mm Round
  • Where, due to the absence of a fascia or the design of the building support fittings  cannot be fixed, the rafter top  bracket and side bracket  provide alternatives.


  • Rise and fall brackets driven into the wall will support the gutter system were there is no fascia and rafter brackets are impractical.

The following is a guide:

  • Security of gutter and downpipe brackets should be checked regularly as part of the overall building maintenance programme
  • Check that no components have become dislodged or loose and that the gutter extrusions have not moved beyond any of the thermal expansion allowance marks in the fittings
  • Rainwater gutter systems should be cleaned out on a regular basis, at least annually, or more frequently in locations where there are large amounts of wind borne debris, eg. sandy areas or in close proximity to deciduous trees
  • The high gloss surface finish retains little dirt, however if required, a mild detergent solution is ideal
  • Brett Martin Rainwater systems are self coloured, therefore painting is not normally required for several years after installation. If painting is required, the following is a guideline for painting the gloss finish rainwater systems and excludes the Cascade cast iron style range:
    • Surfaces of all components should be lightly roughened with sandpaper and cleaned
    • Do not undercoat
    • An oil-based gloss paint is the most suitable

No, expansion should only appear on the downpipe connections.

Fascia brackets should be fixed at centres of no more than 900mm. For roofs with a pitch exceeding 35° and/or are subject to heavy snow loading, support spacing should not exceed 600mm.

If an angle is fixed to the fascia board a bracket should be installed no more than 150mm away.

Yes, by using the Flat Gutter Outlet (BR499). This component is designed to sit inside an industrial metal gutter. Once inserted, the 110mm downpipe can be connected to it.