Installation of Cast Iron Gutters


The most popular way of joining cast iron gutters is by using a low modulus silicone sealant or specialist rubberised bitumen gutter mastic.

The sealant should be spread evenly within the gutter socket applying additional sealant around the jointing hole before placing the gutter spigot into the socket and compressing both parts using M6 X25mm corrosion resistant mushroom head bolts, ensuring the bolt head is on the inside of the gutter.

The washer and nut should be lightly tightened from the underside of the gutter to allow excess sealant to be removed. Do not over tighten as this could result in gutter damage.

Note: If gutters have been cut, remove any loose filings immediately to ensure no discolouration/rust marks on the paint surface. Also check that cut ends, bolts, nuts and any slight installation damage is made good with the appropriate primer and paint.


Before commencing the installation, inspect all fascia boards to ensure they are in good condition and will adequately support cast iron gutters.

  1. Determine the direction for fitting the gutters beginning with socketed end of the gutter.
  2. Position the first bracket 150mm from the end of the run.
  3. Fix subsequent brackets at 900mm maximum centres using a string line for alignment of brackets and ensuring a slight fall towards outlet positions.
  4. Gutters may be cut with a powered disc cutter or tipped hacksaw.
  5. When cutting gutters, ensure there are no loose filings left on the surface as these will cause discolouration of the paint finish.
  6. All cut ends, bolt heads and damaged paint areas should be retouched immediately.

Whilst it is common practice to fit gutters in fascia brackets, some gutter profiles may be fixed direct to the fascia if required. These include OG and moulded gutters which have three predrilled holes per 1.8m (6') length along the top back edge.

Where building designs incorporate no fascia board, other types of bracket will be required, the most popular being side fixing rafter, top fixing rafter and rise and fall brackets with build in spikes. These are all readily available in galvanised/zinc plated steel and other designs are obtainable to suit your specific requirements.


Vertical rainwater pipes would not normally be sealed. Only seal joints between gutter outlet and rainwater pipe or offset plus any joints in a horizontal position such as a 98 degree branch arm or bend.

It is recommended that three small wedges made from timber or sheet lead off-cuts are used to centralise the pipe joints and prevent any wind rattle.


The traditional fixing for eared cast iron rainwater pipes in by using large headed pipe nails which are available in 75mm and 100mm lengths. These are secured in wooden plugs fitted in the brickwork/masonry background. Alternatively non corrosive coach screws, or other proprietary fixings may be used.

When fixing on an uneven or unstable surface the recommended method is to secure fixings by means of epoxy resin in pre-drilled holes.

Fixing of uneared pipes can be by holdfast build in a holderbat, earband or screw to wall bracket. These fixings are all available from stock.


Suitable for use on Plain Half Round and Beaded Half Round gutter profiles, this kit is an efficient alternative to traditional jointing methods. The kit contains 10 EPDM rubber seals plus M6 X 25mm bolts, nuts and washers, suitable for 100mm, 115mm, 125mm and 150mm gutter sizes.

  1. Take the EPDM gasket and push the bolt from the inside of the gutter spigot and then through the gasket.
  2. Line up the gutter and gasket with the socket of the next gutter/fitting and push the bolt through ready to accept the washer and nut.
  3. Check the gasket is square and even between the two gutters and then tighten the nut and washer. Be careful not to over tighten as this may affect the joint or damage the gutter.
  4. Finally use a craft knife to trim off any excess gasket rubber.

When carrying out jointing or installation work on cast iron gutters, always check for any slight damage including paint chips and cut ends and if necessary use the appropriate touch up paint to ensure a complete covering.


It is important when painting cast iron to ensure that all surfaces are completely covered.

Cast Iron Rainwater products are supplied in a grey metal primer with rust inhibitors.

Before fixing on site, the products should be inspected for damage to the finish and, where necessary, wire brushed and spot primed with an appropriate metal primer. This should be followed by two undercoats and one top coat or one undercoat and two top coats of a good quality exterior paint.

For coastal areas please consult your local stockist or paint manufacturer for their recommendations.

After installation ensure that any damage to the coating, jointing nuts, bolts and fixing screws is made good with the appropriate paint.

We strongly recommend all products are painted prior to installation to ensure adequate coating on all surfaces. This will reduce long term maintenance.


Our in house paint coating is formulated to have a life expectancy of 10 years when subject to normal weather conditions and rectification of any impact damage or surface scuffing during and after installation.

Atmospheric pollution and/or the presence of dissolved salts in the rainwater pur greater demands on the paint coatings and can adversely affect the life expectancy.

During installation and assembly of the product and handling, scuffing or impact damage to the coating must be made good to maintain the integrity of the finished paint coating. Likewise, any cutting or drilling operations must be protected with paint immediately to prevent the onset of the rusting process. This touch up reworking also applies to any bolts, nuts and screws used during assembly.


It is important when painting cast iron to ensure that all surfaces are completely covered.

Conventional soil pipes are coated with a black bitumous based finish to conform to BS416.

If over painting, please refer to your paint specialist or manufacturer for a suitable system.


This process will ensure the protection of the cast iron product against resisting from the reworked areas subject to regular annual checks and routine maintenance of the exterior surfaces.

Surface Preparation

Surface Scuffing or Impact Damage: The affected area should be rubbed with emery or sand paper to remove any loose paint or debris and provide a key for touch up. Any rusting from exposed metal should be fully sanded back to bare metal. This process should be carried out as soon as possible after preparation of the surface.

Cutting and Drilling: Remove any burrs or sharp edges and ensure that any oil contaminants, loose dust or metal debris is fully removed upon completion of these operations. Paint touch up should be carried out as soon as possible after preparation of the surface.

If the bare metal faces have been left untreated then any rusting of the exposed metal should be fully sanded back to bare metal before paint touch up.

Painting Process: This process should be carried out in dry conditions with the surface to be treated clean and dry.

Use Hargreaves Foundry semi gloss touch up paint in the appropriate colour and apply an initial coat of paint to the bare metal surface ensuring all exposed metal is covered. Excessive brushing out of the paint should be avoided since this will reduce paint layer thickness and necessitate three or four layers of touch up paint to be required.

When the initial or previous coat is touch dry, apply the second or additional coats of paint to the reworked area ensuring any adjacent areas of paint which have been rubbed during the sanding operations are also painted. It is important that a minimum of two thick layers of paint are applied to provide the desired paint thickness for product protection.