Engineered Structure – Update

I met with the District of North Vancouver again this morning for some further clarification and to again plead my case.  I met with my Plans Checker, the Section Manager – Permits & Licences, and the Building Inspector who will be assigned to my project if I choose to proceed.

It was a productive conversation even though I was not happy with the outcome. I was handed a copy of the DNV Policy regarding lateral loading design which is essentially the same as the Burnaby policy.  So, I should be happy right?  This is what I wanted.

Well – yes and no.  The policy was explained and will only allow ONE approach to structural design per dwelling and apparently all of the Lower Mainland Municipalities have similar policies.  These Municipalities have decided they do not feel that they can allow a generally Part 9 built structure to be mixed with ANY engineered components now that 9.23.13 Bracing to Resist Lateral Loads Due to Wind and Earthquake has been added to the code.  I personally cannot understand this concern that has led to the departure from what Victoria actually intended when they wrote the code, but was now at least relieved to know this was not a crack down on me specifically or owner builders in general – These new policies will apply to ALL builders of single family homes in Southern BC.

I believe the heart of the issue surrounds APEGBC’s assertion that the Part 9 lateral loading allowances are inadequate in their view.  Some more detailed Google searches this evening has shown this is actually a big hornets nest between APEGBC and the BC Code administrators going back a couple of years.  I will do some more research and put together a more in-depth review of the issue to post on my blog in the upcoming weeks.

But for me, it looks like I (and all builders right now) are being caught up in this standoff and the Municipalities are siding with APEGBC.

Some of you would say, “So – Build to 100% Part 9”. While this is possible, it is not easy.

The span tables in the code max out at 20ft spans for a 2×12 at 12″ centres.  The more common 16″ or 24″ centres max out at 19.3′ and 18.2′ respectively unless you have a concrete topping.  But then a concrete topping will bump you into ‘heavy construction’ in the new 9.23.13 in many parts of Southern BC, which again limits room sizes because under heavy construction you are limited by 9.23.13 to a room no wider than 25 ft (more specifically you need a braced wall band every 25 ft). Similar restrictions are present for the roof joists, and I would be maxed out at 18ft for a 24″ o.c. joist (do not forget this would be a diagonal length).

So while it is technically possible to build 100% to Part 9, no one does it any longer.  I do not believe I have seen natural lumber floor or roof joists ever in my inspection business in a home younger than 20 years.  Engineered roof truss and I-Joist floor packages have been the norm for a long time.  On my design I even went to the effort to track down a supplier of an open web floor truss that has industry leading spans of 22ft at 16″ o.c. for a 12″ deep truss.

End result – as my design does have a lot of open spaces and long spans, a 100% Part 9 design is out.  This leaves me with getting the structure designed to Part 4 (fully engineered – think long hand division, ouch) or utilizing the slightly more prescriptive approach of the Engineering Guide for Wood Frame Construction 2009 guide put out by the Canadian Wood Council.  I was today told by the District that I should look at Part C of this guide, as it is closest to the Part 9 system and should only require ‘minor modifications’ to my design.  I plan to spend the weekend learning about this Part C if I can track down the guide to borrow or buy.

SO hopefully there is some light at the end of the tunnel and it is not another oncoming train.

The other positive came from meeting the actual inspector who would be assigned to my project.  I was able to speak with him for several minutes after the meeting and believe we will have a good rapport with each other.  I assured him that I wanted to work closely with my inspector during the build and I believe he was pleased by that.  I could tell he was uncomfortable with many of the products I plan to use because he is not aware of them and is concerned about compatibility between materials.  But he seemed very willing to look at them and I committed to providing a break down of materials with supporting literature once my permit app was accepted.

So – for now I am optimistic about the process and continuing down this journey.  I will need to have my engineer go through the design using the new goal post of the CWC guide Part C and will also need to retain a local engineer to perform all site inspections to confirm what is built matches the design.

I am hoping to keep all of the added costs, including hardware, under $10K – Wish me luck!

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