Comprehensive Estimating for Artificial Grass Installation Projects

Comprehensive Estimating for Artificial Grass Projects

In common with all landscaping projects, every site will have different requirements, and it is recommended that a standard form for site analysis and logistics is followed to ensure continuity and to avoid missing any important factors from your assessment.

An important element of assessing works when quoting for an AG installation is the size and weight of the chosen matting. Small projects requiring a lightweight matting will not involve complex issues regarding site access and close proximity off-loading for example.

The following information should be taken into consideration when compiling a quotation, as the factors shown may impact on the cost of carrying out the works. Some may be treated as Prelims, to be evaluated and added to a tender as a separate figure as part of the administration costs of a project, whilst others should be scheduled as factual monetary costs and subject to Variation Orders as required.

Logistics in Respect of Estimating

• Width of access roads/parking problems/overhead cables/turning problems/ schools or hospitals/any potential hazards or threats to the smooth running of the intended works.

• Condition of driveway/drive surface materials/condition and weight bearing of manhole and other covers. Surface protection for skips/muck away.

• Oil tanks/propane tanks/likely pipe-runs. Emergency cut-off location.
• Trees – sizes and types/surface roots/location issues/overhanging branches/needle drop issues.
• Drain runs, especially new build properties. Evidence of subsidence/potential problems.
• Manhole covers within the footprint of the project. Condition/cover type.
• Soil type. Depth of topsoil. Weed problems/pernicious weed roots. Shrinkage or heave problems identified.
• Japanese Knot Weed?
• Dogs or other pets. Security measures to protect the site for safety reasons.
• Ground boards to traverse site/hire charges.
• Permission/licence to cross neighbouring land?
• Client’s comments reference working periods/restrictions/quiet times (schools etc).
• Underground services plans? Power/CCTV/animal security cables/fibre optics.
• Rental of rotovator or turf cutting equipment, including transport costs.

Ensure that all cost related factors are examined, evaluated, recorded and included in the estimate or quotation. Double check everything before leaving site.

Access to site is probably the most important factor when installing artificial grass. Not only for the logistical problems with importing a heavy weight, length may be an issue when turning tight corners, or negotiating steep steps, and a cost for any systems or ramps should be taken into consideration, not only for the cost of any materials, but also the labour to instal and remove. These costs should be included in the Preliminaries (Prelims) section, shown as a separate item.

Site clearance costs should also be shown separately, and not included in a global figure, especially when quantities may be unknown – clearing overgrown sites for example, where volumes and amounts of rubbish and rubble cannot be assessed. In such cases, a price per cubic metre or grab lorry load may be allowed, and included in the prelims.

Sites may require an application of pre-emergent weedkiller before any base build up takes place. This factor must be included in the CDM Plan, and agreed with the client,

The most common element of an AG installation will probably be the removal of an existing lawn. When assessing the volume of material to be removed from site, grass should be costed separately from soil or sub-soil due to the bulking factor, and difficulties in evaluating the depth of the sward. The use (and/or hire) of a turf cutter to strip and remove the existing lawn will need to be included in the valuation. (The use of a turf cutting machine should also be included in the RAMS documents for the project.)

It is recommended that at least 100mm of topsoil is removed from the site to be covered in artificial grass matting. Therefore, the measurements taken for evaluating the project should be taken after the removal of the grass sward. For estimating purposes, it is recommended that the top 100mm should be removed off site, as it will probably contain grass roots and weeds. Allow 25% bulking factor when assessing the amount of soil to be removed off-site.

The sub-base for the new installation – MOT Type I – will need to be 75-85mm deep when compacted, and it is recommended that 100mm is allowed for estimating purposes. This depth to be measured from the required final level of the underside of the AG matting, allowing for a 15 – 20mm compaction of the sub-base.

Allow 15 – 20mm of Grano-dust for the final laying base, with a maximum depth of 25mm. Any further adjustments of levels should be made using MOT Type 1, for reasons of stability.

Allow for the installation of two separate layers of geotextile membrane – one under the MOT sub-base and the other on top of the grano-dust final layer.

When estimating the costs of the AG matting, apart from taking into consideration the weight, size and other factors previously mentioned, it is important to charge/allow for the full size of the matting, not simply the area to be covered in the design. The customer should be charged for the amount of matting required for the project including off-cuts.

For example, a circle five metres in diameter will require a roll of twenty-five square metres, although the area of the circle is only 19.6m2. The customer should be made aware of this fact, as they will be charged for the amount used including wastage.

Joining rolls and complex cutting and dressing operations should be assessed and time allowed in the labour element of a project. Simply pricing a scheme using standard metre rates can prove costly in some cases.