Building Science

The Building Envelope is what keeps the weather outside and maintains a comfortable and healthy environment inside. It is made up a many components and systems that need to work together to provide an efficient and comfortable living space. DSG knows the building envelope based on Building Codes and Science. The two don’t always agree.



Infrared image, at left, showing missing insulation under a set of stairs, indicated by the red line, on the right.

Thermography, or infrared imaging, allows us to see temperature profiles on the building envelope. These temperature images can identify a large range of problems including:

  • Water intrusion
  • Air Leakage
  • Missing Insulation
  • Overheating electrical systems
  • Roof leaks

We can also find equipment and lines hidden in walls and sometimes even pests. Thermography relies on a very sophisticated relationship between temperature, material properties, relative humidity and moisture content. John has extensive training through Snell Infrared and is a Level 2 Thermographer with Roofing Inspection and Building Science specialized training.

Ice Damming

ice damming

Cross section of roof with improper ventilation causing ice damming and leaking.

Ice Damming occurs when snow on the roof melts and the water runs to the eave overhang where it refreezes and causes the dam. If enough water builds up behind the dam it can leak into the roof or walls and cause all sorts of damage. Contrary to popular believe the cause is rarely lack of insulation, but more often air leakage into the attic. We apply sound building science principals to diagnose the problem, often using an infra red camera, blower door and other diagnostic tools to confirm the problem. Cost effective solutions can then be developed to address the problem, not the symptoms

Moisture Problems

Moisture Problems can come in many forms. Sometimes what appears to be a basement leak is in fact condensation. Attic moisture in the winter time is often a result of air leakage. Excessive moisture on windows can often be traced back to poor ventilation systems. DSG can help resolve these issues by applying scientific principles and extensive building construction knowledge to old and new homes alike!

HVAC Systems

HVAC testingDesign and Commissioning of HVAC Systems is getting more and more detailed as house, equipment and codes get more and more sophisticated. DSG works with well qualified designers to take advantage of leading edge technology to both design and troubleshoot residential HVAC systems. From Balancing HRVs to performing subtle Depressurization Tests to protect against backdrafting of combustion appliances, if we can’t do it, chances are good we know someone who can.

Litigation Support

Expert Witness and Litigation Support is not something you want to enter into lightly. Costs quickly escalate. John structures the development of expert testimony to go to the heart of the matter. His credibility in court is based on clearly demonstrating the link, or lack thereof, between a failure in the building and the loss or damage. We work on through the hierarchy of Codes, Standards, Manufacturers’ Instructions and Best Practice, always supported with Building Science, so that the adjudicator can clearly see the cause – effect relationship. John has presented in small claims court and landlord tenant tribunals, and prepared reports for large insurance claims.