Crawl space venting?

Most crawl space vents are the plastic type where it has a louver, the homeowner is supposed to open and close the vent as needed…

Yeah right

Peter, I think we all know that will not happen, and in reading the IRC, it appears that one might not be able to use an operable louvered vent for that purpose.
I might be incorrect, not sure. My logic tells me that if you are required to provide venting for crawl spaces, they should not be adjustable.

I am not a fan of vented crawlspaces either as long as it is done properly to control moisture and cold from infiltrating the house.

When one reads 408.2 and N1102.1.7 of the IRC it almost sounds ambiguous.

Marcel :slight_smile: :slight_smile:
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I’m awaiting the day she catchs up with any of my methods.

Marcel, in NH any code official can make any amendment to the code as they see fit, so when I go from town to town working it’s pretty much a crap shoot, anyway his office was closed today, I’ll see what happens tomorrow.

Peter; I work in a lot of different towns and cities in Maine also, and it appears that is the case also.

What is up with that, do you think these guys fabricate some of these amendments to suit their needs on that particulat day, or do you think that some of these towns have established some amendments to the current Codes that have been adopted?
Sometimes I wonder if it might not be the officer exercising his empowered duties. Now that would really piss me off if I were to find that out.

I would think that we might be on our guard and request and study the particular town or cities Code adoption, amendments to such and ordinances.

Just thinking off the top of my hat here. Do you think such things happen?

Marcel :slight_smile:

Absolutely!!! I spoke to our state Senate committee hearing on this very subject and told them it’s great to have the IRC as a state code but until the state can control it at the local level you have accomplished nothing.

The IRC rquires venting or conditioning of the space. Conditioned doesn’t mean that it has to be mechanically “vented”----it needs to “communicate” with the conditioned space. This communication can be passive or part of the forced air heating system. This may not always be essential----but it is still a good idea in most cases (at least according to the IRC Gods):smiley:

Peter

In my area, a crawl space is defined as an enclosed area beneath the main floor of a building (Res. or Comm.), and that crawl area has an earthen/dirt floor area.
Venting of this type of area in my opinion is critical, and considered by some to be an art, if the ventilation is to be effective.

A crawl space “type” area with a finished/slab floor is considered a basement “technically”, and does not require ventilation. Personally, if the area can be ventilated effectively, it won’t hurt, and should be ventilated. Now, that’s in my area of the country.

In NH, I’d have to think about it, due to your (assumed) extreme weather conditions. I’d maybe check with your local AHJ and/or your Dept. of Agriculture ( Entomology/Pest Div.) for advise.

Good Luck

Thanks Greg, this is a point of contention that will be debated for as long as there are codes. Problem is, in NH we use the 2006 IRC code book, but the local inspector can supersede any code they want so as a builder we are at their discretion.

It’s really 2 issues…

The first is dealing with the inspector and codes. Unless you want to take him/them on, and that can mean anything between gently educating him or forcing a formal confrontation, you can give him what he wants, and when he’s gone, do whatever you want.

The second is what’s actually correct for the crawlspace, and that depends on the climate zone.

They are not the researchers or industry innovators and if they are regular 35-40 hr per week folks and do not have a passion for their work, they are behind the curve on some fast moving new items.

For example: I was installing Heat Recovery Ventilators in 1981; the codes adopted them as 1 of 6 options to meet ventilation requirements in 1995. It’s 2007 and just about every newer house (even up to $1.5 million) that I inspect or consult on has items not meeting the ventilation codes.

When I go to Home depot or its competitors and view their “Walls of Fan Shame”, only about 1 or 2 out of 10 fans offered meet our codes!!! Its up to the informed to make changes based on the research or innovation that hasn’t reached the AHJ yet.

Oh! The 1.5 million house was an 11 month warranty inspection. It had

(1) 5 bath fans that did not meet code; 1 was already dead!!
(2) an HRV that the contractor lied about being balanced and signed his name to a label on the unit. It showed perfectly balanced at 274 cfm. I used to install that same unit 20 years ago and knew that it would not move that much air against the shrunken duct system I was seeing. So I cleaned the filters and outdoor hoods, inserted my flow measuring collar and found the unit moving about 135 cfm in high speed!!
(3) the groundwater source heat pump was cutting out on cold nights and going onto 100% electric heat. Upon checking things (an old business acquaintance is the manufacturer- Maritime Geothermal), it was found it needed another 4-6 gallons/min.
(4) A ductless A/C for 3 bonus rooms over the garage that (a) would not drain condensate properly, (b) had 2 of the room controls crosswired and (c) the outdoor condensing unit was just about to fall off the wall stand…they just used sheet metal screws to fasten it to the horizontal brackets- out of 8 or so installed, only two remained intact…was a good thing the owners were not using the system due to the other problems
(5) damaged shingles installed on the roof
(6) wine cellar leaked every rain plus a couple other smaller leaks
(7) not enough insulation in the attic
(8) A main load carrying parallel strand lumber (PSL) beam with a support post pushing about 3/8" into bottom of beam. They already had a good set of plans from a well known national manufacturer but chose a second set from a local firm that removed a main beam and put more load onto the above mentioned beam!!

Rant! Rant! Rant! You can screw up a lot of things on a $1.5 million house!!!

and it goes on and on!

I love it when we disagree. I am for not venting crawlspaces based on my years of inspecting and finding vented crawlspaces are more troublesome than ones which are not vented, plastic vapour barrier, insulated and supplied with heat duct, or open into the basement.

IRC states 1 sf / 150 sf. If your crawl space si 100 sf; then you need a vent sized no less tha .667 sf. JMO

The building inspector called me this AM and said I’m all set, no vents OK even though the state of NH goes by the 2006 IRC.

Like I said before every town can adopt what they want. I’m just glad I don’t have to cut a vent into that foundation.

Thanks Peter Been fun… Cookie

Peter

Our Ontario Building Code has the same requirement. Wheather we believe in venting crawl spaces or not the building code states that we should.

I believe the code is minimum and regional Chief Building Officials have the power to alter or ammend the provisions as they see fit or for other benefit as long as it does not endanger or create another concern. In this case I think the research supports the issue that vents create more problems than they alleviate.

Is that your take Marcel?

Cheers,

If all the properties involved with crawl spaces were to be designed and built as it should for the colder climates, yes I would agree that providing vents in the crawl space could be detrimental to the conditions of the under floor structure and the occupants of the dwelling.
It does not relinquish the fact that vents are required by the IRC and the Authority having Jurisdiction in a particular area has the last word, and may dictate what is acceptable or not based on the local Code adoptions.

How do we change the Code to reflect the Science of the Crawlspace? That is a good question, and until the parameters of the Crawlspace design is approved by the I-Codes and reflect the change, I guess we will have to keep writing it up when we inspect an un-vented Crawl.

On new construction, one could request a clairification from the AHJ based on the submitted design criteria and science back-up of the contrary.

Marcel :slight_smile: :smiley:

I personally think that the next five - ten years will tell if ICC made the correct choice in redefining the insulation or ventilation of Attic areas and earthen crawl space areas. I look at the changes from a thermal, infiltration, as well as an infestation/conditions conducive perspective. I/We, in my climate zone answer not only the State/Local AHJ, but also the EPA local representative (our State Dept. of Agriculture). The rules are similar in most cases, but in some cases in direct conflict with each other. Trying to keep up to date with changes day to day and year to year can be confusing.

At least in the northern border states, you don’t have to deal with ST and/or most WDO concerns we do down here. You have problems we don’t have I’m sure, but…

Actually…,

We have active colonies of Termites in Toronto, and some outlaying communities. The cold winters haven’t seem to deter their advance northwards.

Cheers,