Blower Door Test

Effective July 1, 2010 New Residential and Commercial Energy Efficiency State and Local Building Requirements – Chapter 4 Section 401 – Mandatory Third Party Blower Door Testing for air sealing will now be required before occupancy permits are issued.

Our blower door tests are performed with a Retrotec Q5E hard panel door system. The test is performed at an accepted industry standard of (- 50 Pa). This means that the entire living space is brought under a negative pressure as compared to the exterior.

This “forced convection” procedure draws air into the enclosure and simulates the same type of pressure produced by a 20mph wind. The most common reason for a blower door test is to determine the total amount of air leakage into the building envelope. It is important to quantify the air flow into a building, but locating the specific points of air leakage is fundamental to correcting the problems. A thermal imager is considered the ultimate tool when used in combination with a blower door. The thermal camera sees the convective heat transfer being created by the blower door and produces thermal pictures that are taken in “real time”. This process makes it possible to observe and document the exact location where air is entering. The use of this precision equipment allows us to look at the sum total together with the specific areas in order to determine the most cost effective corrections.

Air leaking into our homes is a far greater problem than most people realize. The diagram below, from the U.S EPA illustrates where air leaks and heat loss can occur in your home.


Many homeowners believe that additional insulation means a tighter and more energy efficient home, but this is not always true. Most insulation does not stop air from penetrating the building envelope. It is especially critical to have a continuous air barrier that has the ability to stop all direct air flow into a building.

The obvious motivation for stopping air leakage is to reduce energy costs. The real issue here is not only the heat loss, but the moisture vapors that are getting into the building envelope. The fact is that if air can travel into a building through gaps, so also can moisture. Moisture can be costly as it degrades a structure, makes insulation less effective, and introduces biological contaminants into the living environment.

Effective July 1, 2010 Massachusetts State Building Inspector New Regulations requires that all building permits for new construction or renovations have a third party testing company complete a blower door test and analysis to pass final air leakage inspection.