16 Steps to Self-build: Landscaping and Driveways
Steps 14 & 15: external works and gardening As we reach the penultimate steps in our 16 step guide to building your own home, attention turns outside as patios and driveways are laid and the landscaping takes place. David Snell explains all
Before gardeners can come in, the groundworkers and bricklayers will have to sort out the basic levels around the house and garden, and perhaps create garden walls where needed.
On a sloping site there may be a need for retaining walls to terrace the garden. Garden walls retaining up to 1.2m do not need the input of an engineer; for walls higher than this you will need the walls to be specially designed. In most cases, the need for structural walls can be avoided by utilising a series of lower walls to create terraces. These walls can be constructed using concrete blocks laid flat with an outer facing of either brick or stone. They will need a concrete footing and must have weeper holes to prevent any build-up of water pressure behind them. This is further prevented by backfilling immediately behind the walls with clean stone or hardcore.
Boundary walls have to be constructed on a concrete foundation. They can be built in either brick, blockwork or stone. The stronger walls are double skinned, but single skin walls can be built with piers for support. What’s more, any garden wall benefits in strength by having dog legs, curves or changes of direction.
The subsoil excavated when the foundations were dug (and which, ideally, had been retained and stored) can be used to make up the ground levels. Topsoil can then be spread over the top to a minimum depth of around 300mm.
If the site hut is not to remain as the eventual garden shed, this will need to be removed at this point in the project. What You Need to Know About Constructing Driveways The choice of surfacing material for the driveway is not always down to the selfbuilder. Many local authorities insist on the driveway being of a porous nature or SUDS -compliant, especially if there are trees adjacent or within the proposed driveway area. It’s key to remember that any driveway or patio is only as good as its preparatory base or substrate. Whatever the chosen surfacing medium for the driveway, the vegetable soil must be dug out and a proper consolidated base of Type 1 laid.
If the driveway is to be pea shingle or gravel then thought needs to be given to the edging, which can be concrete or timber. On a sloping site, some thought needs to be given to preventing migration. This can be prevented by lines of concrete edgings across the drive or rumble strips of granite set at various points. There are also plastic trays (which look like hollow egg boxes) that can be laid and filled with pea shingle. If the driveway is to adjoin a tarmac bellmouth (the area directly adjoining the carriageway), then a 1m-wide rumble strip is a good idea to prevent the stones being carried onto the tarmac and ground in.
Paviour driveways are laid on sharp sand blinding, consolidated hardcore or Type 1, and grouted with kiln-dried sand.
Tarmac driveways need some sort of edging in either timber, concrete or paviours. The Type 1 base must be blinded with sharp sand and sprayed with weed killer before the tarmac is laid.
Driveways surfaced with resin bonded with small round shingle can look great when new, but do check that the product you intend to use is porous. They do tend to scuff up when cars with power steering consistently park and turn in the same place.
Most local authorities, and the Highways Agency, require that the area directly adjoining the carriageway, known as the bellmouth, is surfaced in tarmac, whatever the surfacing medium chosen for the driveways within the site. Planning regulations also require that no surface water from driveways should be allowed to flow onto the carriageway and that there should be a drainage channel with a grille to divert surface water into a drain or soakaway. This is normally positioned at the junction of the tarmac bellmouth with the rest of the driveway.
It’s also worth noting that any works to or beneath the highway must be carried out by approved contractors. These are companies approved by and listed by the local authority and/or Highways Agency and, principally, they carry the necessary and relevant insurances to cover such works to a public place. However, most authorities allow works up to the edge of minor roads by normal contractors so long as a licence has been obtained.
Works to driveways and pathways within the site can be carried out by your
normal contractor. That would include any bellmouth directly adjoining the carriageway, so long as there is no proposal for it to be adopted.
Pathways and Patios Pathways or patios usually come within the remit of the groundworkers. Once again, any pathway or patio is only as good as its substrate.
Concrete pathways and patios have largely fallen out of fashion. If they are chosen then the base needs to be consolidated hardcore or Type 1 and the concrete must be laid in bays with compressible material between each to avoid cracking.
Most pathways and patios these days seem to be slabbed, using either concrete slabs or the much more attractive, and often cheaper, alternative of natural stone. Once again the substrate or base is the important bit and this should be Type 1, properly laid to the levels and consolidated using a wacker plate or roller. The slabs are bedded on sand and cement dabs, with a minimum of five to each slab, and tapped home and to level. Grouting can be sand and cement or kiln-dried sand brushed in when the slabs have firmly set.
Paviour paths and patios are laid in exactly the same way as for a driveway.
The Landscaping Any new house will always look better when the ‘soft’ architecture is in place. So thought needs to be given from quite an early stage as to how the garden may look (see page 174 for more on landscaping).
Of course, the final decisions will depend on the eventual levels and the positions of garden walls, driveways and patios. No matter how experienced a self-builder you are, the chances are that you will be caught out by the reality and the effect that seemingly small slopes or level changes can have.
Many planning authorities require a tree planting and/or gardening scheme to accompany the application. For the reasons stated above, you may not always be able to put this into practice and there may have to be some variation.
Planning authorities will also require you to specify the boundary treatments, such as hedges, fencing or walling. Walling is usually the province of the groundworkers and bricklayers. Fencing is usually within the remit of the gardeners.
The discerning self-builder will eschew panelled fencing in favour of close boarded fencing for screening. If a view is to be maintained, then post and rail fencing with the addition of pig wire is an attractive and cost-effective option.
Hedging can be purchased bare rooted and planted in the winter season. The ground does need to be properly prepared with good drainage, good topsoil and the addition of a feeder. The local authority may well specify the mix of plants and these will, most likely, be native varieties.
Lawns can be seeded or turfed. Seeded lawns will need the topsoil to be raked level to a smooth tilth before seeding in the early spring. Care needs to be taken with weeds. These can be sprayed off in the autumn/ winter with the type of weed killer that does not hang about in the soil.
Lawns to be turfed should have the topsoil raked level and to a fine tilth before the turfs are laid out and tamped down. This can be done at most times of the year but care needs to be taken in the summer to keep the turf damp. If there is a heavy infestation of weeds in the soil, then these will need to be eradicated before the turfs are laid, using a weed killer that degrades. Otherwise, the weeds will find their way through.