Homeowners have been told to be wary of tradesmen who knock on their door claiming to be passing through the area.
Trading Standards officers with the Highland Council suggested Brits exercise caution in dealings with speculative builders.
It said people should be sure the person carrying out work on their property is reputable, as the body receives complaints every year from those who have experienced aggressive behaviour, poor workmanship or inflated prices.
Spokesperson John Laing explaining they should "think twice before employing someone they dont know, or without getting several quotes and clear details of exactly what work is to be done".
He added anyone employing tradesmen who have problems with payments or standards should report them to the authority as a matter of urgency.
A recent HSBC survey found loft conversions can add more than £13,000 to the value of a home, while conservatories can boost the price by more than £7,000.