Trying to water proof cabin in high wind and water area
I am building a cabin on a ridge overlooking San Bernardino. It has extremely high winds that drives water horizontally and upward onto the cabin. Before my contractor started on the sideing I got a 2nd opinion from another contractor who has built on the rim. He found lots of places for potential water instrusion that my contractor basically said wouldn’t matter. I stuck with the original because he is a good contractor and I still have a garage to be built. Thats the back story. Moving forward a couple questions:
2nd contractor said the protruding rood beam should have been cut back flush with the wall face and sealed that way. My guy said he could seal it anyway.
2nd guy said I should leave off the plastic facing on the insulation (haven’t gotten this far yet) because it would help the house to dry out. He also said I should apply a couple of vent through the open ceiling (a water and windproof type) to help vent moisture.
Thoughts on the plastic and the vents?
Replies
What's your cabin made of? Is it stick built or logs. Does it have sheathing and a vapor barrier? A photo or two would help.
What plastic facing on insulation? Is he saying you should vent the whole house or just the attic?
No photos for a week. Turned back because I didn't have chains. Stick built. Open loft to the ceiling, no attic. I haven't installed insulation but the bid calls for vapor barrier, which I could remove,
The beam can be waterproofed and still protude. I don't know about the other issues. As far as water proofing, but compromising the building envelope with vents and omitting the vapor barrier, ostensibly to help vent moisture strikes me as a very bad idea.
If your cabin is sided with clapboard siding or shingles, water will get through. What you need is a drainage plane behind the siding and in front of a waterproof weather barrier as shown in the attached sketch. This can be asphalt building paper or house wrap such as tyvek. These are waterproof but breathable which will allow any moisture in the wall to escape.
If the cabin is used when it is cold and the cabin is heated, the interior vapor barrier is absolutely required. Without a vapor barrier warm moist interior air will penetrate the wall and when it hits a cold surface it will condense causing mold and rot.
I know exactly what your dealing with. I live in Crestline, not too far from the Rim. I can absolutely see where wind and water running up and into a house is very possible around here. To share a story, a neighbor and friend of mine has a home built in 1928 with a living room addition that was built in 1940. Her living room walls leak because the 10x10 joist beams that hold the 2nd story bedroom above the living room run outside the front of her home too with no tape or barrier work. That coupled with the old 2nd story wooden deck has helped filter water into the house and now the beams have slowly rotted away over the last decade. Even after we cut the deck off and did our best to weatherproof her wall, wind and water from these last storms still made it up and into her walls possibly at the roof line or the corners. I stayed the night this last good rain storm and it sounded exactly like someone was pressure washing her walls. The previous owners had the place caulked at every gap, probably to stop the leaking but the sun has opened up cracks over time and now it still just pours bulk water in and with how much rain and wind we get up here her walls are never dry for months out of the year. Needless to say all her joists need to be replaced now, possibly more water damage we haven't even found yet, it's going to be an expensive process, but it goes to show that second contractor is right for wanting to trim those joists and do the waterproofing and taping. Up here you have to everything possible to not give that bulk water a chance to get in. If the joists didn't protrude outside and/or the house was properly wrapped and taped she might not have this emergency on her hands but they just didn't build it like we do now back in 1940. If it's gotta leak it's gotta breath, and if not, it's gotta be as tight as a submarine. If I had a choice, I'd go with the second guy who wants to do all the waterproofing, seems like he has an eye for this stuff already. Good luck neighbor!
To answer your question on plastic sheeting on the interior insulation, you probably don't need it, and definitely don't put up plastic sheeting between it and your drywall. Here is a quick video why from Matt Risinger, great resource btw for other building science questions. https://www.youtube.com/watch?v=q8fOMBlfh3A also watch https://www.youtube.com/watch?v=CIcrXut_EFA