About Us


Sigma Inspection Services is a Canadian company based in Guelph, Ontario. The owner and principal inspector is Darren Johnston, a Level 3 Thermographer with 17 years of residential and industrial construction experience.

We offer various building inspection services as well as thermal imaging for a wide range of applications. Thanks to our network of professionals, each with different backgrounds and specialties, Sigma can provide service to most of southern Ontario, as well as other parts of the country.


In 2003 we began as a home inspection company, servicing Guelph, Kitchener-Waterloo and the surrounding area. We were continually upgrading our qualifications, equipment and philosophies in order to better serve our clientele and meet demand for more specialized inspections. Over that time we also had the privilege of working with some of the best inspection professionals in the business, many of which have become part of our team.

Our pursuit of excellence and diversity led to a significant expansion of our services which now include commercial and industrial inspections, energy audits and infrared surveys. After getting involved with thermal imaging in 2008, Sigma Thermography was founded and quickly grew into an integral part what we do. On January 1, 2012 the company was rebranded as Sigma Inspection Services to amalgamate the building inspection and thermography companies and operate under one identity.