As we look to meet new effective RSI values required in upcoming energy code provisions, and exceed these standards in high performance sustainable construction, the use of continuous insulation (uninterrupted by wall studs, plates, lintels, floor lines etc.) as part of our exterior wall assemblies is the way of the future.  That being said, casually adding insulation to a wall assembly can also be extremely problematic if done incorrectly.  When insulation values go up, the exterior sheathing plane becomes colder, leaving opportunities for condensation that must have the ability to dry to the exterior.  Adding continuous insulation such as XPS (blue foam board insulation), which is extremely vapour impermeable restricts the ability for the wall assembly to dry as it creates the ‘double vapour barrier’ bag that can trap moisture within the wall assembly and lead to deterioration.

ROXUL Comfortboard IS is a rigid mineral wool insulation sheathing board that is non-combustible, water repellent, fire resistant and sound absorbent. Comfortboard IS is an exterior non-structural insulation sheathing that provides a continuous layer of insulation around the residential building envelope.  Mineral wool insulation (such as Comfortboard IS) is hydrophobic (it can get wet), and highly vapour permeable such that it won’t limit exterior drying of the wall assembly.  With the added rigidity of Comfortboard IS, rainscreen strapping and exterior cladding products can be installed directly over the insulation boards (fasteners penetrating through the panels into the structural framing).

For some context, a 2×6 wall  (16″ centres) with standard R-20 batt insulation is rated at an effective R-Value of just under R-17.  In some BC Climate zones (and the City of Vancouver) an effective R-value of R-22 is going to be the baseline standard.  Adding a 1.25″ Comfortboard IS panel outboard of the sheathing plane bumps this wall assembly over the effective R-22 required (when considering the effective R-value of all components).

In high performance assemblies, we will likely see more instances of framing reduced to 2×4 construction to allow an increase in the exterior continuous insulation thickness without increasing the overall assembly thickness.

The City of Vancouver is unique in that it does not adopt the BC Building Code like other regions of the Province including Greater Victoria and Vancouver Island.  The City of Vancouver utilizes the Vancouver Building Bylaw as their own independent code.

Changes to the Vancouver Building Bylaw are pending, and reflect some interesting requirements.  Many of theses will go above and beyond the increased energy standard provisions we will see in the December update to the BC Building Code.  Here are a few of the changes the Vancouver Building Bylaw will now require in residential homes:

1. No More Door knobs –  The City is moving towards a standard of improved accessibility for all buildings by eliminating door knobs in favor of lever type hardware

2. Provisions for rainwater collection – New homes are to have plumbing systems dedicated for rainwater collection

3. Conduits to permit future installations of solar power systems

4. 220V charging stations for electric vehicles

5. R50 for attic insulation

6. R22 Effective for Wall Insulation

7. Required upgrades to heating systems

The City of Vancouver has indicated an expected 1.7% cost increase, or $5700 for a 2500sf home to achieve these additional standards.  These provisions do not impact us directly in Greater Victoria or Vancouver Island, but it is always interesting to see what direction the province perhaps will be heading overall if they follow suit with the City of Vancouver.

New energy provisions in the National Building Code that will be effective in the British Columbia Building Code in December begin to require the performance of building enclosure assemblies to achieve effective R-Values, opposed to nominal values prescribed historically.  Effective R-Values are a far more accurate evaluation of these assemblies, and this shift in the code is a slow but steady step in the right direction of achieving more energy efficient buildings.  However, to determine effective R-Values, some calculation is required.  In response, the Canadian Wood Council has developed a free online tool to look up the effective R-Values of many common wall assemblies we see in residential construction.  There is also the ability to simulate custom wall assemblies to determine the necessary values.  Here is a link to the CWC Wall Thermal Design Tool.  Enjoy!