Skirting: Are automatic vents a good idea?

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mdnagel
Posts: 180
Joined: Thu Jan 06, 2011 12:39 am

Tue Jun 18, 2019 3:13 am

I'm doing some research on replacing my skirting and ran across a mention of automatic vents, vents that open and close based on temperature (usually(?) opens above 40 degrees, fully at 70 degrees).

Is it really OK to completely close off air circulation below 40 degrees? Isn't venting about managing moisture? (air circulation)

I'm in the Pacific Northwest, low temperatures might get into the teens, but that's about it for typical lows. I can get up to 70" of rain where I'm at, with most occurring during cooler periods.


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Greg
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Tue Jun 18, 2019 6:26 pm

I have them, but remove them and fill the holes with foam board for the winter. I would rather have the insulation when it's -10* with a wind blowing.

Greg
"If I can't fix it, I can screw it up so bad no one else can either."

mdnagel
Posts: 180
Joined: Thu Jan 06, 2011 12:39 am

Tue Jun 18, 2019 9:19 pm

Greg, are there not moisture concerns when there is no ventilation? I know that when it's extremely cold that humidity levels tend to be very low. Do you target based on up-coming temps, in which case what temps trigger you into action, or just a general date?

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Greg
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Wed Jun 19, 2019 5:25 pm

Just in general, once cold weather starts setting in I button things up.

Greg
"If I can't fix it, I can screw it up so bad no one else can either."

mdnagel
Posts: 180
Joined: Thu Jan 06, 2011 12:39 am

Fri Jun 21, 2019 5:30 am

After reviewing my ventilation requirements I'm figuring I'll just go with standard vents. Cheap, flat screen (which I currently have) at 16" x 8" provide for 70.7 sq-in of open space. At 1' of open ventilation space for each 150' of floor space I come out to needing 9.18 sq-ft, or approximately 1,322 sq-in of ventilation. I'd need about 19 of these vents.

It looks like "professionals" did the original skirting install: the quality of the work seems quite a bit better than the quality of stuff that I figure that the owners had done, hence the belief that professionals did the skirting work. Anyway, the installers failed to account for the mesh. The open area of the holes for the vents (16 holes/vents) comes pretty close to the 1'/150' ratio, but when adjusting open area for mesh screen (14 1/2" x 5.5" of 4x4 mesh [is rated 65%]) it comes out about 60% short of TRUE open area: I estimate the ratio to be about 1 ft-sq per ventilation per 239 sq-ft of floor space. I'm on a concrete pad (with vapor barrier), but I doubt that this was factored in, or that it even really matters.

While I'm here, a couple more questions (every solution has its issues!):

1) Anyone run vents up and down (long axis vertical)? (8" screen width would fit in between the major ribs of the panels, making it a lot easier to install (perhaps could look to install on the outside face of the panels [which would allow me to hide the cut edge of the panels])

2) How do people seal off (or perhaps screen off) the end of roofing panels? The ribs create openings (bottom I'll look to pretty much close off by resting on Z-flashing): rib height on the panels I'm looking to use is 7/16", and, I'm guessing, the width (at the base) is about 1", making for an open space of about 0.33 in-sq.

Here's a picture of current skirting setup (pressure treated 2/4, bolted to concrete pad, at the bottom; 2x6s flat side out and about 4' OC (for the OSB panels- not sure if I'll leave this as positioned or look to move and add additional to better facilitate these 3' roofing panels [which I'll just screw in on the flats rather than on the ridges as these would require when on a roof]):
ExistingSkirting2.jpg
ExistingSkirting2.jpg (209.71 KiB) Viewed 856 times
As one can see, I've got a ton of cleaning up to do under there! I'll be dawning a respirator and suit: expecting a fair amount of debris from dead things. This is a multi-part project. Repair rim joist (about a 10' section in this back side). Replace rear door. Total re-plumb with PEX (as I'll be messing with the belly wrap anyway). Cleaning up and repairing the belly wrap: at some point there had been a burst water pipe; owner stuffed insulation and then blue-tarp'd it! :roll: And, of course, new skirting. Hoping to be able to get all of this done in a span of about 10 days.

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