COWBOY builders cost homeowners a staggering £1.5bn a year in bodged jobs, according to a survey. It also reveals that one in five builders is "financially dodgy" with either a court judgement against them or a poor credit rating.

According to the National Home Improvement Council, a good way to choose a contractor is to make sure that the trader belongs to a reputable trade or technical association. Many of these belong to the NHIC and their members are qualified to reliably undertake building work including major renovations and extensions, on behalf of householders.