Homeowners in McHenry County are being warned of home improvement scams that show up during the summer months.

Groups of con-artists target senior citizens but will also approach other homeowners and offer subpar services that require them to spend hundreds or thousands of dollars to repair, according to the McHenry County sheriff’s office.

In these scams, a sales person for a driveway sealcoating company offers homeowners a “great deal” to coat the driveway with left over driveway sealer from a previous job, the sheriff’s office said. They give the homeowner a very low rate.

The sales person uses high-pressure tactics to get the homeowner to agree to the deal, the sheriff’s office said. Then, a team of seal coaters uses “substandard materials” which wash off after the first rain.

Homeowners are advised to ask a contractor for a detailed estimate and proof of insurance before any work is done on their home, as well as waiting at least three days before committing to a company.