Wet pour surfacing

Definition

A 'wet pour' surface is a blended mix of rubber granules bound together, having been manufactured on site and laid on an existing suitable, or specially prepared base to provide a continuous surfacing free of seams or joints.

NB. In exceptional circumstances on a large area, one join may be necessary.

This basic system with varying base components is employed by most suppliers today. Developments include environmentally friendly recycling, employing former truck tyres (SBR), materials which are tougher and more durable than synthetically produced EPDM granules.

EPDM - Ethylene Propylene Diene Monomer is synthetically manufactured rubber, formed in sheets and then cut into granules of varying sieve sizes.

VIRGIN EPDM – is a term used to emphasise that the granules are not recycled SBR. However, watch for EPDM recycled and not truly virgin granules, which are much cheaper for the supplier to purchase from the manufacturer.

Site suitability

Wet pour systems cure quite rapidly, after mixing, so the supplier must be able to get the mixing plant reasonably near the play area (within 20 metres).

If the existing base is hard, i.e. concrete, tarmac, etc., surfacing can be superimposed upon it, but there may be a 'step up' for the child, representing a trip point. NB. The supplier should make a proper edge finish, by cutting a 'channel' in the existing formation to key the surface edge. The surfacing must extend to the full BS recommendation before the ramp edge begins (see RoSPA leaflet on surfacing areas).

The existing hard base can be removed (at extra cost) and the new surfacing laid into the 'well' created on top of a suitable foundation to give a flush edge finish.

If no hard base exists, excavation to reduce levels is required and a minimum 150mm depth of MOT type 1 stone should be provided as a foundation, upon which the requisite thickness of 'wet pour' surfacing can be installed. The area should have a retaining edge to the perimeter, preferably a pre-cast kerb, brick or similar. Timber is adequate but gives long-term maintenance problems.

Check existing equipment meets current British/European Standards and has a reasonable life expectancy. Breaking out equipment and repairing or replacing in 'wet pour' surfacing is expensive and, if only patching, very unsightly. Avoid installing expensive new surfacing under sub standard equipment.

Selecting your supplier

• Ask for references of recent installations and those over three years old for you to inspect.
• Check the financial status of the supplier. Regrettably a number of firms offering very competitive prices in recent years, have failed to survive, taking your guarantee with them.
• Request an Independent Consultant's Test Report, for the specific product and thickness/ thicknesses offered. A 500mm sq. test sample should be poured on site, for testing by a reputable test
  house. RoSPA can provide indicative testing at an economic price.
• Expect a minimum of five years guarantee, not only for wear and tear, materials and workmanship, but that the installation will still perform within British Standards criteria.
• Check to see that the supplier has made provision for securing the installation until it is fit to walk and play on and accepts liability to that time.
• Enquire whether the supplier is a member of the Association of Play Industries and as such, bound by a Code of Practice and Technical Guidelines.

Coloured surfacing and in-laid colour features

Some coloured rubbers are more sensitive to ultra violet degradation than others. Check with your supplier on life expectancy for colours other than red and green. In-laid features are now very popular to provide added 'playvalue'. However, the introduction of additional joins/seams does make the installation more vulnerable to vandalism and future 'trip' hazards.

Maintenance

The periodic removal of pollution should be the only maintenance necessary and this can be effected by power washing or the application of a washing detergent, a copious amount of water and brushing with a stiff broom.

Surfacing located beneath trees, may attract moss or similar. Any proprietary pathway moss killer should be employed but care is needed in its application because of possible hazard to children.

The most common forms of vandalism are burning with a small cigarette lighter or with fuel assistance and graffiti painting. The latter cannot be erased and the best remedy is to paint over with a matt finish industrial floor paint. Burnt areas will need to be cut out and patched by the supplier. Small holes can be repaired using a repair kit from the original supplier and cracking can be sealed with a glue gun.

Inspections

Inspectors should be asked to look for any cracking, lifting or breaking up of the surface granules. This can be due to:

• Installation during inclement weather conditions
• Chemical problem with the binder
• Failing to ensure proper bonds between joins
• Insufficient strength in the sub-base mix
• Excessive impact absorbency in the sub-base mix
• Insufficient binder in the hard wearing course (usually noticeable by excessive sweeping off of granules)

Lifting and breaking up can be due to:

• Insufficient binder in the mix
• Poor resistance to ultra-violet light
• Thermal or soil movement
• Tree roots

In such circumstances a site inspection by the supplier should be arranged.

Other problems sometimes encountered include excessive wear under a moving play unit, e.g. swings, roundabouts, usually the consequence of poor quality materials or mixing, or insufficient binder. NB. Wet pour rubber does not permanently adhere to edge kerbs, gaps that develop between the edge and the surfacing, are usually a geographical problem and beyond the supplier's control.

Prepared for RoSPA by Barry Baker, MILAM