Construction Questions

[tworivers]

I've got a question for the architects/engineers here. Seemed worthy of a new thread.

I've been watching the 4 buildings designed by Studio 3 go up here in N Portland -- two on the SE side of the intersection of Mississippi/Fremont and 2 at opposite corners of Vancouver/Shaver. I'm just assuming that they're all the same developer because I've never seen buildings go up this slowly. All four of them. I mean astonishingly slowly. You'd think they'd want to get in on the apartment market asap but what do I know.

My question, though, is regarding standards around how long plywood can sit uncovered on the side of a building absorbing all manner of nasty weather. Is there no structural degradation that can happen when a half-built structure soaks up rain storm after rain storm during your average Portland fall/winter/spring -- in this case, with hardly any apparent construction activity happening at times? Mold risk? Are there regulations governing this? Inspectors enforcing? I have my doubts already about the quality of this firm's work but watching several of these buildings soak up so much moisture this winter (and last) while progressing at a snails pace has really had me wondering...

[bvpcvm]

This is a great question, one that I've been wondering about too. Anyone?

[maccoinnich]

Plywood that will be exposed to the weather during construction, but not after construction, should be specified as "Exposure 1". From a quick google I can't find any firm definition for how long it is ok to leave Exposure 1 plywood exposed.

[Nunya]

The American Plywood Association (APA), won't define what it means since it really varies based upon a lot of environmental conditions. Humidity, temperature, length of time, amount of water, amount of slope to shed water, etc.... They leave it open ended to cover themselves. The closest you'll find is something like this

Exposure 1 panels may be used
for applications where construction delays may be
expected prior to providing protection or where exposure to
the outdoors is on the underside only

Source: https://www.apawood.org/Data/Sites/1...-datasheet.pdf

You will also see language that says something like it's permitted for 'short period of time or Exterior Exposure is required for extended periods of time'. So you are really on your own to figure it out. As long as you don't get warping or delamination and its dried out after it gets wet and before finishes you typically are fine. It's not uncommon to put a small gap between panels (1/8" to account for swelling per APA recommendations). I've seen some builders spray sealant on plywood when they've been working in very wet seasons and anticipate it being exposed for longer then they'd like.

[bvpcvm]

I used to live right next to the black cubes going up on 28th and Thurman (which started before covid and are STILL not finished), and you gotta wonder, with standards like that, how they're going to perform after 10 years. There were a lot of days with those sitting exposed to the rain.

[zilfondel]

As long as plywood and other types of wood that is outside and exposed to the elements is allowed to dry out completely after the building envelope is sealed up, it will be fine. What takes years of exposure typically to rot. Wood installed on a vertical surface is going to drain water and it shouldn’t be a major problem.

OSB on the other hand is a totally different animal, and that stuff falls apart like shit and rots all the time when water or moisture saturated it. However it to can withstand some time spins exposed to the elements.

In any case these are means a methods and are really up to the contractor to protect their materials that sothey don’t fall apart, and the liability is going to be on them. The APA publishes guidelines for weather exposure for the different grades of plywood and engineered lumber. If the contractor decides to follow those guidelines is another matter but generally they will be OK.