I just replaced the foundation of my 1 story 1910 Craftsman house. The house is shingles from the first floor up and it has 1×8 V-rustic siding from the foundation up to the first floor (on the cripple studs). In doing the foundation we had to remove the bottom 2 courses of siding, in some areas more, in some areas less. I also am taking this opportunity to replace old funky pieces higher up that are simply distressed due to age and neglect.
In any event, I can’t get my final inspection for the foundation job until the siding is put back on. I know that the inspector is going to be looking at crawlspace venting and it is my understanding that you need to provide 1 sq. ft. of vent area for every 150 sq. ft. of crawlspace. I have 1300 sq. ft. of crawlspace which by code means I need to have 8-2/3 sq. ft. of vents. Looking at the available vent screens at the lumber yard I choose the least ugly of the bunch and based on how large they were (5.5″ x 14″), I figured I’d need ~ 16. That seems a bit high (intuitively speaking) but according to the code that’s what I need.
First off, these vent screens are pretty ugly and I can’t really find any that seem to look good with a house of my vintage. Secondly, I’m a little concerned at the quantity that I need as per the code. I do have some locations where I can put them that are relatively out of sight but I’m sort of surprised at how satisfying this code requirement is threatening the aesthetics of my project. The quantity that I need is just as big of a concern as their appearance. My house is roughly 52′ x 25′.
Does anyone have any suggestions?
thx, jonR
Replies
I would frame out or box out a large section in the location that is not so visible and then screen it in, so as to create your own custom size crawlspace vents.
I would also consider adding a decorative set of louvers or maybe even lattice over the screen. I seem to remember seeing a close spaced vertical and horizontal lattice on an older home and it looked like it "belonged".
You may be required by code to space out the vents to some degree, as well as having a certain size area of vent per square foot, in other words you may not be able to put just one big screened vent in the back, might need at least one or two on each side or distance from the corners.
First you may want to check a little deeper into what your code requirements are. I have no specifics for CA, however where I live CS ventilation requirements are reduced from 1/150 to 1/10 of that (1/1500) provided you have good cross ventilation and a 6 mil plastic vapor barmier on the CS ground. The plastic vapor barrier is a really good building practice anyway, and if you want to make it even better, glue it to the CS walls, make sure any joints are well overlapped, and that it is installed tightly around any center piers, etc. You may not want to take it all the way down to 1/1500, but a vent on each side of each corner, and one in the middle if each wall would be plenty enough.
BTW - if you Google around a bit, they have some nice looking CS vents that are designed to visually fit in much better with a vintage type house. Maybe someone else here has a link or 2...
Another route you could take is to have a closed (unvented) CS. The first requirement for this is that your CS is bone dry, so if you have any water infiltration at all down there forget about this one. The idea is that you install a very tight vapor barrier on the floor, insulate the CS walls, and them pump conditioned air into the space. For this setup something better than 6 mil poly is normally used for the vapor barrier.
>>1 sq. ft. of vent area for every 150 sq. ft. of crawlspace.
In my area it's 1/150 with no moisture barrier, 1/3oo with
Check out the Building Science web site on venting and talk with your inspectors to see if they'll buy in to 'ventless' conditioned air crawl.
(If that works in your area.
As an HI, I have inspected a few hundred conditioned crawls and never seen any moisture related problems in the structure, even where it was clear that te crawl had moisture problems.
"Ask not what the world needs. Ask what makes you come alive... then go do it. Because what the world needs is people who have come alive."
Howard Thurman
http://rjw-progressive.blogspot.com/
Thanks everyone for your input. I've Googled around to see if I could find some vents that looked OK and I had some luck; will look into that in more detail later. I think the first thing I need to find out is the quantity of vent openings needed. I'd like to put the minimum amount in and then concentrate on gettings ones that look good with respect to the architectural character of the house.
I wasn't aware that codes are relaxed in some locales depending other considerations such as vapor barriers--interesting to note.
A few more conditions about my crawlspace that I didn't include earlier: Around 15% of my crawlspace area is actually a basement. This space is defined by retaining walls and has a concrete slab. It is accessed by one of those old fashioned cellar doors (right off the driveway), and there are concrete stairs down to the basement. I'm not sure if this would change the requirements in any way...I sort of think not.
Additionaly, along the lines of moisture barriers, I have a drainage system around the entire perimeter of the foundation which was installed with drain rock, perforated pipe, and that cloth stuff--this was done as part of the foundation job. The system drains to a sump & pump and then is pumped out to the street. It works quite well when testing it, but I haven't had it through a rainy winter yet to give it a real world test. I'm not certain whether this would change the requirements for venting. Does anyone have any hunches as to whether it would or not?
As far as my inspector goes, this is also troublesome. I just got assigned a new inspector and he has quite the reputation for being inflexible, seeing things only in black and white, and being quite uncooperative. I'm not looking forward to discussing something like this with someone with this type of reputation so it should get interesting #trying to stay a bit positive. <g>)
-jonR
If you went to the library they might have a copy of the building code for your area. A Google brought up this. You also might want to check your county's or city's web site to find out what code you are under. If the CA building codes are based on the IRC (which I think they might be) read sections R408 and R409. When you deal with inspectors I find that they give you more respect if you can demonstrate an actual knowledge of the subject that is backed by doing your homework - as opposed to repeating what your brother-in-law's cousin told you... Or worse still "someone on the Internet told me".. :-)
Here, what you need at a minimum is for someone who has a CA code book.
Don't vent if you can help it - treat it as conditioned space.
Jeff
Thanks again guys for all these suggestions. Matt's suggestion of actually studying the subject in order to talk with the inspector more effectively is a great one and one that I probably would have eventually figured out. :-) However, it was good to have someone simply suggest that now so I can be prepared for the first inspection with this new guy, rather than have to come back later with all the knowledge after the fact.
Based on what I stated in my last posting about my crawlspace does anyone think the following would have any bearing on how much venting I would need.
1. 15% of the space is basement with a concrete slab floor
2. There is a drainage system with sump pump that goes around the outside perimeter of the entire foundation.
Just wondering if anyone has any direct experience with issues such as these. In the meantime I'll be digging up code books in order to come up with a course of action.
-jonR
2. There is a drainage system with sump pump that goes around the outside perimeter of the entire foundation.
That, in general, is a bad idea - bringing outside water inside, even to a sump pump.
Jeff
No, the sump pump isn't inside...did I say that it was inside? Even if I didn't, maybe I should have been more explicit and state that the sump pump is outside. The sump + pump is outside the house; there is no way I wanted to put it inside.
Funny you should mention this though: The foundation contractor wanted to have it drain into my existing sump + pump that's in the basement and I said...no, no, no!!! I will continue to use that one in case the outside one gets overloaded and as a second line of defense (which I hope doesn't happen) but there is no way on earth that I would bring the water inside.
-jonR
Perfect ... just checking ;o)
I fully appreciate the checking! :-)
-jonR
That seems a bit high (intuitively speaking) but according to the code that's what I need.
We're way over codified. Codes are necessary of course but in many cases they go way beyond what is needed to get the job done if it's a technical issue or to provide a reasonable degree of safety if it's a life safety issue.
The 2006 IRC (most jurisdictions haven't switched to 2009 yet) requires the 1/150 ratio but doesn't require anything at all if there's a taped VB that goes up the walls 6" and that's taped also (sectionR408.3-1).
Runnerguy