How badly does rain damage ongoing construction? If it rains while concrete is being poured, does just delay the curing of the concrete, or does it have other detrimental effects? What about for other materials like treated lumber or particle board? Does rain harm a house that has been framed but not yet roofed?
Not going to comment on the concrete, but getting wood wet causes it to swell and this can damage your construction or cause other detrimental effects. For example, in some places like Arizona you have to build during the rainy reason, because if you build during the dry season your house will swell and everything will get screwed up. Prolonged exposure to the elements can also cause bare wood to crack or warp, so while a few rainstorms won’t hurt it, you still want to get things wrapped up as fast as possible.
Rain won’t delay the curing of concrete, and keeping concrete wet actually results in a harder set.
If it rains during a pour, though, your chances of getting any kind of decent finish are out the window.
Treated lumber isn’t really effected, usually, if it’s already fastened. Treated lumber left in the rain and then left in the sun will make a good rocking chair.
OSB, or oriented strand board, which I think you mean when you say particle board, is not resistant to weather at all. One good rain and it will start coming apart at the edges. A couple soakings and it’ll expand in thickness and fasteners will start to pull through the top layer.
Regular dimensional lumber used for framing, will withstand rain fairly well. But repated rain/sun cycles will begin to warp members that aren’t securely fastened, like studs or roof rafters.
Any kind of loose lumber that is left laying out in the rain, even stacked, is liable to be ruined.
I used to rough frame houses and I can tell you one good rain won’t do any real harm. I suppose if you took forever to complete the framing and had multiple hard rains you could run into problems, but in my experience the biggest problem with rain was that it usually cost the day’s work because no one wants to saw through wet wood or climb around on the top of a slippery wall.
Not to mention that footings should be poured on firm, undisturbed soil. If water has collected in the bottom of an excavation, it needs to be pumped out and any mud or softened soil should be scraped off before the pour. Otherwise, you could get future unwanted settlement of the structure.
some engineered lumber (plys or other wood material glued together) can withstand getting moderately wet and drying without damage. framing lumber anchored in place might not be damaged by getting wet and drying. getting rained on during a day or two doesn’t mean it’s wrecked if it gets to dry. unused lumber especially framing lumber should be covered.
concrete cures by having the water in it become part of the material. concrete will cure under water. keeping concrete wet enough while curing is an issue.