A HUDDERSFIELD firm has warned against "cowboy" builders.
Marshalls, based in Birkby, took action after reports of driveway installers cold calling consumers across the UK.
A spokesman for the firm said: "Be very wary of installers who can "start tomorrow" or arrive on your doorstep looking for work.
"Reputable installers usually need many weeks' notice before they can start as not only are they busy, but they need time to plan your job correctly and order suitable materials.
"Busy, professional contractors do not solicit business by cold calling on consumers. If they are that desperate for business to intrude into the privacy of your own home, there has to be something fishy."
Other tips were:
* Never accept a verbal estimate - A written contract is essential
* Seek at least three quotes. These should be on headed paper with an address and telephone number - not just a mobile number.
* Choose the contractor you are most comfortable with and one that understands your needs. Remember cheaper isn't always best
* Don't take them at face value. All professional contractors should have a business address and land line telephone number. Check them out
* Is the installer prepared to offer a long-term, written guarantee? If not, beware.
The spokesman added: "As a reputable manufacturer of hard landscaping and block paving products for gardens and driveways, and as an affiliate Member of The Trading Standards Institute, Marshalls is at the forefront of trying to stamp out this kind of activity."
Paul Smith, of West Yorkshire Trading Standards Service, said: "We always warn consumers about the potential problems of dealing with people on their doorstep
"We recommend that people use an approved trader."
