Water, Water Everywhere: solving the secrets of trapped moisture in walls

It happens every spring. Every build and building inspector knows the script: the phone call comes about the basement leak, a visit to the home is arranged and the inspection takes place. The wet insulation is visible through the ‘plastic stuff’. The plastic stuff is known as the vapour barrier, and in some cases, the air barrier.

During the investigation no leaks are found anywhere. A perfectly installed air gap drainage membrane is present, weeps are fully connected to an active sump, AND there is even a capillary break placed between the footing and the foundation wall (you don’t see that every day!). read more

HRVs vs. ERVs

Some contractors may be hearing or reading mixed messages about the application of ERV technology vs. the older HRV technology. Much of this conversation centers around the appropriate technology for cold weather applications. A quick review is in order. The history of air exchangers, air to air heat exchangers or heat recovery ventilators in residential applications was very clearly tied to excessive winter moisture and window condensation problems as houses became more energy efficient and tighter. HRVs were developed specifically for the removal of moisture in R-2000 and other energy efficient housing programs. Introducing cold, dry fresh air to replace the high humidity exhaust air has the ability to quickly bring down the relative humidity in cold weather. For example, when the outside air is at 0 0C (32 0F) and 100% RH, just 30 L/s (60 CFM) of ventilation can remove approximately 15 liters (3.24 gallons) of water a day. Using an ERV with a latent effectiveness of 50% would cut this moisture removal capability in half.read more

National Building Code Section 9.36: A New Day for Energy Efficiency

For the fist time in National Building Code history, Part 9: Energy Efficiency sets a minimum benchmark with Section 9.36. To achieve this, there are two optional compliance methods: Prescriptive or Performance.

The prescriptive approach allows the designer to “pick” appropriate envelope solutions from the tables and charts. There is provision made for limited trade-offs (i.e. increasing wall insulation to off-set limited u-value of stain glass custom window) whereas the performance option allows for the minimum efficiency target to be met through showing compliance through modelling (i.e. Hot2000). The performance path further allows the designer to take a more customized approach in meeting the minimum energy efficiency standard.read more