Cast Iron Rainwater System Specification

Heritage Foundry cast iron rainwater systems combine traditional cast iron construction with a range of gutter, rainwater pipe, hopper and accessory profiles suitable for restoration, conservation and new-build projects.

This page provides general specification information for Heritage Foundry cast iron rainwater products, including applicable standards, dimensions, installation guidance and maintenance requirements.

General Specification

System

System Type: Gravity rainwater drainage system.

Rainwater outlets, gutters, pipework, fittings and accessories should be selected and installed as a complete rainwater drainage system.

System Performance

Design Standard:
BS EN 12056-3:2000, Clauses 3-7 and applicable National Annexes.

Design Rainfall Rate:
In accordance with BS EN 12056-3:2000 National Annex NB.2, Category 1.

The rainwater collection and distribution system should provide complete drainage without leakage or unacceptable noise.

Cast Iron Guttering

Heritage Foundry manufactures cast iron gutter lengths and fittings in a range of traditional profiles.

Available Gutter Profiles

• Half Round Guttering
• Beaded Half Round Guttering
• Deep Half Round Guttering
• Victorian Ogee Guttering
• Moulded Ogee Guttering

Standards

Gutters and Fittings:
BS 8530, formerly BS 2997.

Manufacture:
Cast iron rainwater goods manufactured in accordance with BS 460:2000.

Available Gutter Sizes

Depending upon the selected profile, gutter sizes include:

• 100mm
• 114mm
• 125mm
• 150mm
• 100 x 75mm
• 125 x 75mm
• 125 x 100mm
• 150 x 100mm

Outlet Sizes

Available outlet sizes include:

• 63mm
• 75mm
• 100mm
• 75 x 75mm
• 100 x 75mm
• 100 x 100mm

Individual product pages should be consulted for the sizes and outlet combinations available for each gutter profile.

Gutter Finish

Transit Primed Finish

Suitable for preparation and final painting on site.

Factory Painted Finish

Heritage factory-applied painted finish is available in a selection of colours. The required colour should be specified when ordering factory-painted products.

Gutter Jointing

Gutter lengths and fittings overlap at the joint using the traditional socket and spigot arrangement.

Fixing slots are provided for assembly using suitable M6 mushroom-head zinc-plated bolts, nuts and washers.

Apply a suitable exterior-grade low-modulus silicone sealant evenly across the joint before assembly.

Gutter Fixing

Suitable corrosion-resistant fixings should be used for the supporting structure.

Cast Iron Rainwater Pipes

Heritage Foundry cast iron rainwater pipes are available in traditional round, square and rectangular formats with associated fittings and accessories.

Depending upon the product range, pipes may be supplied with traditional eared fixing points or as plain pipe for use with separate pipe clips.

Standards

Rainwater Pipe and Fittings:
BS 2997.

Manufacture:
Cast iron rainwater goods manufactured in accordance with BS 460:2000.

Available Pipe Sizes

Depending upon the selected system, sizes include:

• 63mm
• 75mm
• 100mm
• 75 x 75mm
• 100 x 75mm
• 100 x 100mm

Pipe Finish

Transit Primed Finish

For preparation and final painting after installation.

Factory Painted Finish

Factory-applied Heritage painted finish in the selected colour.

Pipe Fixing

Pipe clips or integral fixing ears should be securely fixed to the supporting wall.

Suitable corrosion-resistant wall fixings should be used.

Pipe joints should be sealed using an appropriate exterior-grade silicone sealant while allowing approximately 3-4mm vertical movement within the joint for thermal expansion and contraction.

Rainwater Pipe Accessories

The Heritage Foundry rainwater range includes compatible:

• Bends
• Branches
• Access Pipes
• Offsets
• Shoes
• Rainwater Heads and Hoppers
• Pipe Collars and Clips
• Associated Fittings

Care & Maintenance

Correct installation and periodic maintenance will help maximise the service life of a cast iron rainwater system.

Routine Inspection

Gutters and rainwater heads should be cleaned regularly to prevent the accumulation of leaves, moss and other debris.

Downpipes should remain clear and free flowing. Joints, brackets and other fixings should also be inspected periodically to ensure they remain secure.

As a minimum, the complete rainwater system should preferably be inspected twice each year:

• At the beginning of autumn
• At the end of winter

Additional inspections may be required where buildings are surrounded by trees or exposed to severe weather.

With appropriate installation and maintenance, cast iron rainwater systems can provide a very long service life.

Use of Ladders

Repainting & Finish Maintenance

Paint coatings should be periodically inspected for:

• Chips
• Scratches
• Impact damage
• Surface corrosion
• Exposed bare metal

Any damaged areas should be cleaned, prepared and repaired using a compatible primer and topcoat.

Where cast iron is cut during installation, any exposed bare metal should be properly prepared and coated before or immediately after installation.

Transit-primed products require an appropriate complete paint system to be applied following installation.

Factory-painted products should also be maintained throughout their service life. Any damage occurring during handling or installation should be repaired using suitable touch-up paint.

Cleaning Around Cast Iron

When cleaning adjacent brickwork, stonework or other building surfaces, cast iron components should be protected from contact with acids, concentrated alkalis and other aggressive cleaning chemicals.

Planning Your Rainwater System

When specifying a cast iron rainwater system, consideration should be given to:

• Roof area and rainfall intensity
• Gutter profile and capacity
• Number and position of outlets
• Rainwater pipe diameter
• Building height
• Pipe and gutter fixing locations
• Existing architectural details
• Conservation or listed-building requirements
• Required surface finish and colour

For system sizing, refer to the Heritage Foundry flow-rate information or contact us if assistance is required selecting suitable gutter and rainwater pipe sizes.