Free guide to energy efficient wall construction now available
Online guide helps builders meet Vancouver building code's new standards
For years, the 2x6 wall with R-20 batt insulation has been an accepted standard in the B.C. home building industry. But in the City of Vancouver, it's becoming a thing of the past.
The Vancouver Building By-law requires an R-22 level of thermal performance in wall assemblies. And as of 2015, it now requires an effective R-value that's calculated on the actual thermal performance of each wall component. Before, the R-value was nominal, an assumed performance based on the insulation installed.
This shift to an effective R-value is a game-changer, says Lorne Ricketts of RDH Building Engineering.
"The new code really sets the stage for continuing to move energy performance requirements forward," he says. "I think that this is the stage where we're going to see the steepest learning curve in terms of how to build these walls. In the future, as the requirement potentially gets increased again, we'll be ready as an industry to adapt."
Requirements lead to deeper walls, exterior insulation
Ricketts says it's now nearly impossible to meet the Vancouver Building By-law using the traditional 2x6 stud wall — unless a builder includes additional insulation. Wrapping insulation around the outside of a building, uninterrupted by framing, allows significant increases in the thermal performance of the wall.
To help builders learn how to meet higher effective R-value requirements, the Homeowners Protection Office has published a free downloadable guide, R-22+ Effective Walls in Wood-Frame Construction in British Columbia. The guide was prepared by RDH with Ricketts as the primary author.
The guide includes:
- General building science related to walls
- A chart that shows how wall thickness and R-value are related for various assemblies
- Detailed discussion of several above- and below-grade wall types
- A summary guide for quick reference.
It also, importantly, helps builders learn to calculate effective R-values. "Those calculations are a critical step, the first step past standard framing and into effective R-values," says Ricketts. "The guide is supposed to help the industry get over that initial hurdle, as we move towards energy efficient buildings and higher R-value walls."
Better walls allow builders to reduce the home's mechanical systems
Ricketts says it's important for home builders to embrace improved wall construction.
"Walls form a big portion of energy loss through the enclosure," he says. "If you start at the envelope you can reduce the initial loads on a system, then reduce the size of mechanical systems that are needed to meet the loads, and really bring down the energy consumption associated with houses."
With requests to do presentations, and increased phone calls to the RDH office, Ricketts says there has been a lot of interest in the guide and in the new Vancouver by-law. And while he expects exterior insulation will be the necessary future solution as standards continue to evolve, he's also seeing many builders opt for 2x8 wall construction to meet the requirements without altering their general building practices.
"Those 2x8 walls are right on the line for complying with the R-22 effective requirement, but builders are going that way because they're familiar with only using cavity insulation," says Ricketts. "But in the long run, as R-values requirements go up, it's going to be difficult to just do deeper and deeper stud walls.
"To me, we're at a bit of a tipping point. With Vancouver's by-law energy requirements, and this new guide, it moves us beyond that 2x6 framed wall and into the realm of more thermal efficiency. Once you get one or two inches of exterior insulation on your wall and builders have learned how to do that, it won't be as hard to keep upping the thermal performance requirements in the bylaw."
Download your copy of the guide: R-22+ Effective Walls in Wood-Frame Construction in British Columbia