Eli5: how does it raining on partially built houses not ruin those houses

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The problem with water isn’t that it is there, but rather that it doesn’t leave easily. In an unfinished house there is only the studs which will dry quickly because they are exposed to sunlight and lots of air while this might cause some warping everything is held togeather and doesn’t really move. Now if you get water into a finished basement you now have water in the walls in the carpet or under the floor. Air cant get to these places so they stay wet for long periods of time and that causes problems. There are also materials that don’t do well when wet regardless of how long they are wet for and those don’t go in till after the house is water tight.


There is a method to the madness when building a house and combatting weather. The foundation won’t be harmed at all by short term wetness. The framing goes on quickly and the sheathing right behind it. The sheathing is either weather resistant zip board or its regular OSB with a house wrap installed that keeps most moisture from penetrating. The subfloor decking is a special material that is meant for short term water exposure, like Advantek plywood. Also, small holes can be drilled in the floor to eliminate ponding and allow the water to drain to the basement. The roof is again either zip board sheathing or its regular plywood that quickly gets coated with tar paper, which is fast, cheap and easy and keeps out 90% of the rain. At this point, windows and doors go in, and the house is generally considered “dried in” after all the openings are filled. Next step is installing The final siding and roofing, which can go on pretty much at the same time as the interior mechanical, electrical and plumbing systems get roughed in. Absolutely no drywall or insulation or carpet or basically anything that can’t get even a little wet without adverse effects goes in until the house is fully dried in. So basically, it’s all about moving fast and using purpose built materials in the early stages, and getting the right systems in place before you install anything that can’t be exposed even short term.


Wood does soak up water, but it also dries out over time. There’s usually not anything exposed to rain that will get damaged. Any wood that’s touched the ground is treated to resist rot, so I’m if there is a puddle of water on the foundation for months due to rain It won’t rot, and any other wood will shed water and dry out naturally. The wood frame goes up first, followed by the roof to protect the walls, flooring, paint, etc. that would get damage by rain if it was installed without a roof. If your house is wood framed, it will naturally absorb moisture from the air on humid days and dry out on dry days. That’s why you may see cracking paint at some point because the wood will swell stretching the walls and contract when it’s dry causing cracks over time. If you have old wood doors, you may notice on humid days its difficult to open or close the door because rot swells from moisture.


3 words – order of operations Basically there is a point in building a house when it’s all still pretty exposed that it’s not a big deal if it rains. But then as it progresses there will be a point where it’s paramount to get the roof up and generally waterproof the interior in case of rain so generally contractors will plan around this and put in a lot of manpower and resources into construction at that point. Once that’s done then the house can survive rain like any other built house.


It does but it remains exposed to the elements and will just dry up. Once it gets to the point where things can get damaged(usually the roofing and insulation is next, followed by drywall), it gets tarped up and flashing(the weird white paper you see on a house without brick or siding) is put on.