My back garden backs on to a busy road on the way into the town and I would like to build a high wall or sound barrier to reduce noise levels. As this is to the rear of the property, is it necessary to get planning permission if the proposed height is over 2m?

Traffic noise can be a nuisance and an annoying distraction, writes Noel Larkin. The combination of engine noise, faulty exhaust pipes and tyres meeting the road surface can make a real racket. Noise generated by tyres can account for up to 90 per cent of overall traffic noise. Road noise also increases with traffic speed. In recent years, road builders have developed quiet tarmac. This is finished with a smoother surface and with perforations. This allows water to escape off the road and has helped reduce noise. Regrettably there is still a lot of old, worn and noisy tarmac on our roads.

A new wall as you suggest is probably the best solution to help reduce this noise. The more solid the wall, the quieter it will be, because sound waves are reflected by dense objects. The sheer mass of masonry walls made from stone, brick, or concrete make them the best for blocking traffic sound.

Capped walls made of brick, stone or block, can be erected as an exempt development as long as they do not exceed a height of 2m at the rear of your property. If the wall is made of plain blocks or mass concrete it must be rendered or plastered. You should check your planning permission as in some situations conditions attached to an original grant of planning permission, for example for a rural house, may have prohibited the building of a wall.

Alternative natural boundary treatments such as fences and hedgerow planting may have been required. It is important to check the planning history of your site as exemptions do not apply where there is a pre-existing condition requiring an alternative. Any development normally considered as exempted reverts to needing planning permission where it would contravene a condition of a planning permission or endanger public safety by causing a traffic hazard or obstructing the view of road users. You also need to be conscious of the effect any new wall may have on a building, feature, site, character or landscape of special-amenity value or special interest.

Check your planning permission and the local development plan to see if you are within a special-amenity area or if there are any restrictions such as development with the curtilage of a protected structure or the like.

However, if you want to build higher than the 2m limit, which you may have to, to help reduce noise, this will require planning permission. Talk to your local chartered building surveyor as they can help in producing any required plans and in preparing the application on your behalf.

Trees can also help to reduce noise or a water feature close to the house can mask the background traffic noise.

Noel Larkin is a chartered building surveyor and a member of the Society of Chartered Surveyors Ireland