NHBC’s guide to safeguarding homes and trees
It’s the peak time of the year for new gardeners to plant trees and shrubs – but do you know some root systems can damage your home?
Inexperienced gardeners often pick up the first thing that catches their eye with little regard to its eventual height or demands on a garden.
The prime culprit is the Leylandii conifer, often seen towering over gardens, planted when they were tiny and often sold as ‘dwarf’ conifers by unscrupulous (or ignorant) sellers in the 1970s.
Even experienced gardeners can fall foul of this – in my case, a now huge Phormium in the front garden which is proving impossible to tame, sold as a ‘medium-sized’ plant.
A basic rule of thumb to remember is that roots often extend further than the MATURE height of the tree, taking moisture from the soil. The distinction between shrubs and trees is also fuzzy – a large shrub is often bigger than a small tree. When in doubt, CHECK THE FINAL HEIGHT AND SPREAD.
The National House Building Council (NHBC) has shared top tips on planting new trees near your home:
- If you garden on clay, new planting may cause it to shrink, while removing trees and shrubs may make it swell, so plant new trees away from your home. Find out the mature height and position it at least three-quarters of this distance from the house.
- High water demand trees (such as elm, eucalyptus, oak, poplar, willow and some common cypress species) should be planted no closer than one-and-a-quarter times the mature height.
- Climbers such as ivy and Virginia creeper hold onto house walls with aerial rootlets using twining tendrils or aerial roots which could damage loose mortar. Plant these at least three meters away from your home.*
- Before cutting down or pruning a mature tree, check with your local authority to make sure that it is not protected by planning conditions, conservation area restrictions or a Tree Preservation Order.
- Allow enough room for trunks and large roots to grow safely. Be careful if planting near drains or lightweight structures.
- Ask your neighbour if planting a tree near their property is OK, especially if the mature plant will cut off their light or view. You could be liable for the cost of repair if the trees you plant cause damage to their home.
- Regular pruning of fast-growing, thirsty trees such as the Leyland cypress (Leylandii) or eucalyptus (which I grow as a shrub, hard pruned every other year for the new foliage), will help to reduce the amount of water taken from the soil.
- The level of soil around your home should be kept below the damp proof course (generally 150mm or two brick courses). Paths should be the same distance below the damp course, except where they have been designed to provide level access into the home. Air bricks, permanent ventilators or perpend vents should not be blocked or covered by soil or paving.
This I take issue with. Ivy, especially, has had a bad press over the years. As long as the mortar and brickwork are sound, and you take care to keep gutters, the roof and windows free from climbers, there is evidence to suggest they can provide insulation to homes, as well as providing a wildlife habitat.
Further advice on property maintenance can be found in NHBC’s A Guide to your new home – a practical guide to looking after your new home, available at www.nhbc.co.uk/homeowners.