Technical Questions

When NAFS was first introduced the only places you could use an LW door defaulted to what was in NAFS: door between home and carport, or between home and attached garage. The FENBC task group working with RDH on the original replacement best practice guide proposed use of the nomograph in the Annex to CSA A440.4-07 (I believe it was this version), and included a black and white version of it in the published version to facilitate adoption by industry and regulators.

A subsequent update to the BCBC treated the top of the door identically to the top of a second-floor window where the overhang ratio is intended to protect the window head. Using the same ratio to the top of the door did nothing to protect the door sill, which never made sense. But some official must have reasoned what’s good for a window should be good for a door. Does it make sense? Of course not.

The original replacement guide was largely forgotten as were the nomographs in it. I guess the recent update produced by RDH for BC Housing retained it, which is probably a good thing: it is the most sensible guidance we have, and BC Housing was wise to adopt it, IMHO. Its legitimization by BC Housing gives the method some credibility, as I don’t believe the current A440.4 retained it.

As for the water test pressure required at any building in Canada, the Canadian Supplement to NAFS has solved that problem. As a consensus standard that is referenced in the code for this purpose, no one can fault you for relying on it in the absence of professional guidance. When professionals require a higher level of water penetration resistance, you are obliged to use their numbers if they are in the specs you bid on, and may have to live with even if they’re not. Your default WTP value should not be less than CSA A440S1, and some consultants will require higher values, whether out of wisdom or their fear of litigation.