Rainwaterdirect - Cast Aluminium Guttering & Pipes

Cast Aluminium Installation

Generally
BS 8000 Workmanship on building sites, Part 13, Code of practice for above ground drainage and sanitaryware
appliances: 1989 is relevant in general terms.

Handling and storage
All components should be handled with care to avoid damage and stored on level ground clear of traffic and under cover.

Cutting and drilling
Gutter and pipe sections can be cut and drilled on site with normal metalworking tools, and holes or slots formed to accommodate fixings.

Where powder coated materials are cut it is recommended that exposed edges are painted with a matching enamel touch-up paint (available from Alumasc). Deburr all cut edges.

Gutter falls
Bracket support: Where possible a fall of 1:600 to 1:350 (maximum) should be allowed for. However gutters can
be laid level if this is not possible.

Gutter fixing
Outlets and angles should be positioned first, followed by full lengths of gutter, and finally infill lengths cut to fit at the plain end. Screw brackets to fascia board at maximum 915mm centres or as recommended by Alumasc for non-standard profiles or special situations.

Allow one extra bracket for each angle or outlet. Fix brackets so as to position the gutter centrally and as close below the roof edge as possible, taking into consideration locality and roof/slope/finish. Use No. 12 x 38mm quality zinc plated, cadmium plated or sherardized twin thread roundhead screw and washer. (Countersunk screw for rafter brackets).

Where high winds are expected, a small bead of sealant must be applied between gutter and bracket as a flexible adhesive. An occasional screw, fixed through a slot in the back of the gutter and into the fascia may be preferred, at a minimum of two per length.

Direct fixing can be used for Victorian Ogee and Moulded No. 46 gutters, with slots provided as necessary, generally at 600mm centres. When ordering material always specify 'Direct Fix'. Follow specified recommendations for gutter position and laying to falls as above. Use No. 12 x 38mm round head screws as above, but also using aluminium washers to allow for thermal movement.

A sealing washer shall be used when direct fixing Moulded No. 46 gutters to prevent leakage through the rear slot in high flow circumstances. Alternatively a small amount of sealant can be applied around the slot and screw head.

Cast Moulded No. 46 must be fixed with the sole of the gutter level. This can be achieved by using a continuous batten between the gutter and fascia, or the supplied fixing support bracket at a minimum of two per 1830mm length.

Always ensure that all fixing slots provided are used. Fixing centres may vary, but always fix at the centre of each slot to allow thermal movement.

Gutter jointing
Cast gutters generally overlap at the joint with a spigot and socket. Slots are provided for fixing by bolts, nuts and washers to provide support and retention of the union, together with a suitable sealant. Thoroughly clean joints and wipe dry. Unpainted cast gutters should be primed (Dow Corning 1200, Feb Primer
No. 5).

Apply sufficient sealant between the gutter and the socket union clip so that some squeezes out of the joint when tightened. A minimum 3mm thickness should be applied right across the joint and around the holes.
Screws in the sole should be tightened first. Do not overtighten screws. Clean off surplus sealant.

Use M6 mushroom head aluminium screws with aluminium nuts and washers. Available from Alumasc in natural finish only, but matching enamel touch-up paint is available.

Downpipe fixing
Fix pipe sockets and brackets at 2.0m centres with minimum No. 12 x 50mm round head twin thread screws or similar as above, to plugged walls with a washer beneath the screw head. The large hole size is designed to accommodate traditional pipe nail fixing or 6mm minimum proprietary expanding bolts as preferred.

Downpipe jointing
Where sockets are supplied separately from the downpipes, these must be lightly driven home onto the pipe, which should be cut square and be free from dents or burrs. A light application of low modulus silicone sealant must be applied to both surfaces for a guaranteed waterproof joint. Use a block of wood or similar protection at the pipe and socket end to prevent damage when fitting.

When assembling pipe stacks, allow a 4mm gap between the open end of the top pipe and the flange of the lower socket, to allow thermal movement. Pipe and socket joints should be sealed with a low modulus silicone sealant, which will remain flexible. This should be applied over a caulking material such as 6mm polyethylene backing foam, to seal the joint effectively.

Site painting
Degrease with white spirit and clean thoroughly. Prime with zinc phosphate or similar aluminium primer, followed by at least two coats of full gloss paint on all exposed surfaces. Undercoating is not required.

Site testing
Allow for sufficient curing time of the sealant. The gutter outlet should be plugged, and the gutter filled with water to the overflow level. After 5 minutes the joints should be checked visually for evidence of leaks.

Model Specification

Gutters
Alumasc Heritage Cast Aluminium heavy grade gutters and fittings to BS 2997:1958 (1980) and to BBA certification where applicable. Profile to be ........... in ........ mm size(s).

Material to be cast aluminium.

Colour to be factory applied electrostatic polyester powder coated ........... RAL number ............ or plain aluminium finish. *

All manufactured by Alumasc Exterior Building Products Ltd, White House Works, Bold Road, Sutton, St Helens, Merseyside WA9 4JG.

Installation
Seal evenly across the joints with low modulus silicone sealant, eg Dow Corning 791 and retain with M6 aluminium screws, nuts and washers in accordance with manufacturerÕs jointing instructions. Gutters to be direct/bracket* fixed at a minimum 915mm centres with additional fixings at or near fittings. Use No. 12 x 38mm twin thread screws bright zinc plated and passivated to BS EN 12329:2000. Use countersunk heads/round heads and washer for direct fix. (Good quality sherardized or cadmium stainless steel plated screws may be used).

Downpipes
Alumasc Heritage Cast Aluminium heavy grade aluminium extruded downpipes and fittings to BS 2997:1958 (1980), BS EN 1462:1997, BS EN 612:1996, BS EN 12020:2001, BS EN 515:1993, BS EN 573:1995 and BS EN 755, in .....mm material and to a BBA certification where applicable. Profile to be circular/square/rectangular*
in .......mm size, with eared/non-eared* sockets.

Colour to be factory applied electrostatic polyester powder coated ...RAL number.... or plain aluminium finish.*

All manufactured by Alumasc Exterior Building Products Ltd, White House Works, Bold Road, Sutton, St Helens, Merseyside WA9 4JG.

Installation
Pipes to be secured with eared sockets/pipe clips* at 2.0m maximum centres. Use plugged fixings No. 12
x 50mm round head twin thread screws with washers, bright zinc plated and passivated or cadmium steel plated
screws may be used.

Allow for a 4mm thermal movement gap in joints. Joints to be sealed with a bead of low modulus silicone sealant over polyethylene backer foam as manufacturerÕs jointing instructions.

The Alumasc Rainwater Drainage Design Service

Alumasc Technical Services can calculate the most appropriate system of gutters and downpipes for all of the rainwater systems that are offered.

Using dedicated design software in conjunction with the requirements of BS EN 12056:2000: Gravity drainage systems inside buildings Ð Part 3 calculation of the most efficient drainage set up takes into
consideration the following criteria:

• Catchment area
• Local rainfall intensity
• Building life and safety factor
• Size and flow rate of gutters
• Frequency and size of outlets and downpipes

The gutter flow software, used by Alumasc automatically checks the capacity of downpipes used and suggests
the minimum size to which down pipes can be sized.

Care and maintenance

Routine Inspection
Regularly clean out rainwater heads and gutters and ensure that downpipes are clear at all times. Check that joints and fixings are secure by periodic inspection, not less than twice a year, and preferably at the beginning of Autumn and again at the end of Winter. Brush down unpainted surfaces lightly to inspect if required. Plain finish goods will develop a natural grey aluminium oxide coating which forms a hard protective layer, preventing additional oxidization.

Ladders
Even with a well fixed installation, ladders should not be rested against the gutters.

Polyester powder coatings
Clean polyester coated surfaces by regularly washing down with a warm detergent solution, and maintain
paintwork in good condition. Do not clean with caustic or abrasive materials. In aggressive atmospheres such as marine environments and industrial areas BS 6496:1984 requires this cleaning to be carried out at up to three month intervals to maintain optimum appearance and durability.

Lightning Linkage
Lightning linkage fixings should be tested regularly in accordance with the specialist electrical maintenance instructions.

Notes
If using stainless steel fixings, insulated washers must be used.Specify matching touch-up paint if required.