9.2 Drives, paths and landscaping

SITEWORK STANDARDS

9.2 - S1	Sitework standards
9.2 - S2	Ground stability
9.2 - S3	Foundations and construction
9.2 - S4	Freestanding walls and retaining structures
9.2 - S5-S7	Garden areas
9.2 - S8	Landscaping

Sitework that complies with the design and the guidance below will be acceptable for private roads, drives, paths and landscaping.

GROUND STABILITY

Where the ground may become surcharged during construction, precautions should be taken to ensure stability.

Retaining structures that give support to the foundations of a home should be completed before work starts on the construction of the foundations of the home. The use of gabion and crib structures to retain ground that gives support to homes, garages, roads, drives, and drainage systems is not acceptable to NHBC.

FOUNDATIONS AND CONSTRUCTION

Items to be taken into account include:

(a) specification

Appendix 9.2-A gives details of suitable constructions for private roads, shared private drives, private drives, car parking, paths and patios.

(b) protection of drains and services

Where underground drainage or services are below a private road, shared private drive, private drive, car parking area, path, or patio they should be protected against damage as described in Chapter 5.3 'Drainage below ground' (Design and Sitework).

(c) drainage

All private roads, shared private drives, private drives, car parking areas, should have adequate drainage and disposal. See Appendix 9.2-A.

Paths and patios abutting the home should generally be at least 150mm below the dpc and be laid to falls away from the home unless a channel or other suitable means of collection and disposal is provided.

(d) ground levels

Finished ground levels should be compatible with:

• dpc levels
• cover levels of drainage access points
• depth of underground services (gas, electricity, water, drains)
• drive and path levels.

(e) timber decking

Decking should be constructed in accordance with the design or guidance published by the Timber Decking Association.

(f) patios

Foundations and constructions suitable for patios are given in Appendix 9.2-A.

FREESTANDING WALLS AND RETAINING STRUCTURES

Items to be taken into account include:

(a) construction

Freestanding walls should be constructed in accordance with the design or BRE Good Building Guide 14.

Retaining structures should be constructed in accordance with the design or BRE Good Building Guide 27.

(b) guarding

Guarding should be provided to retaining walls more than 600mm high in accordance with Clause S7(a).

GARDEN AREAS

(up to 20m from the habitable parts of the home)

Old foundations, concrete bases and similar obstructions occurring within 300mm of the finished ground surface should be removed.

Construction rubbish and debris should be removed from garden and other areas around the home.

The ground around the home can be compacted by machinery and storage of materials during construction as well as when topsoil is being replaced and this can affect the structure of the soil and its draining capability. Where this occurs within 3m of the home appropriate action should be taken to suitably restore the drainage characteristics of the soil.

Any ground disturbed during construction should be re-graded to conform to the general shape of the adjacent ground.

Subsoil should not be placed over topsoil and any topsoil disturbed should be reinstated. Garden areas should be provided with topsoil to a thickness of not less than 100mm. The topsoil should not contain contaminants which are likely to present a hazard to users of the garden area.

Items to be taken into account include:

(a) guarding and handrails

Guarding should be provided where:

• structures are retaining land more than 600mm high to which people have access, or
• a path is adjacent to a vertical difference in level of more than 600mm, or
• the ground adjacent to the path falls away at an angle of more than 30° from the horizontal, or
• the total rise of a flight of steps exceeds 600mm. A handrail should be provided.

The guarding should be at least 1100mm high, not readily climbable by children and a 100mm sphere should not be able to pass through any openings in the guarding.

(b) steps

Any steps should have a maximum rise of 220mm and a minimum going of 220mm.

LANDSCAPING

If landscaping is specified, the work should be carried out and completed in a competent professional manner. Landscaping should meet with the guidance given in the Design section of this Chapter.

The NHBC recommendations on the protection and planting of trees should also be followed. See Chapter 4.2 'Building near trees' (each section).