are blowing my mind.
I just returned from a residential elevation certificate.
The homeowner has installed vents from Crawl Space Door Systems.
They are 16"x16".
The net opening is 180sq.in., yet each vent claims to cover 395sq.ft.
The vent is nothing more than a hole in the foundation wall with plastic screening and louvers. I just don't get it.
I guess it's not my job to get it. As long as I include the engineer's cert. with it, I guess I'm fine.
That is a very high opening ratio. Cover your butt and measure the openings yourself. I do not think screening is acceptable, and nothing can be movable.
Paul in PA, PE, PLS
I've looked at the 1616CS vent. The slats are fixed. (Louvers are movable).
The calculations assume water flow not applicable to the shape.
My calculations give a range of 90-100 square inches of opening.
I plan on contacting that engineer as well as the South Carolina Board if neccessary.
Paul in PA
The louver was fixed.
A 16"x16" open hole yields 256sq.in. These vents claim 18sq.in.
The part that gets me is they claim to cover 395sq.ft.
I looked at the Smart Vent website and they claim similar areas.
Both sites claim to be "Engineered Certified FEMA Compliant."
Reference FEMA TB1-08. Engineered openings are either certified by the ICC-ES or an engineer/architect. The unique engineered opening certificate (architect or engineer) is good only in the licensee's state and for a specific address. The ICC-ES certification is universal.
If the product is not ICC-ES certified (see FEMA TB1-08) then certification must be address specific and certified by the engineer.
Note the address field is left blank. Plan/certificate "stamping."
Thanks gtinla.
The certificate I referenced was SC specific(I'm in SC).
Sorry, I'm not getting it.
Are you saying that makes it no good?
See page 24 of TB1-08. "The certification shall identify the building in which the engineered openings will be installed."
Ugh...These things suck.
I'm just going to leave that blank. If FEMA needs it, the homeowner/insurance agent can contact the issuing engineer.
I also added a disclaimer to Section D about all info. regarding installed engineered flood vents supplied by manufacturer.
Well done! You should not alter/amend/edit the engineered opening certificate.
Any product with an ICC-ES report needs the following on an EC; engineered opening
checked, comments to include model number, photo of representative vent.
Looks like Smart Vent is suing other vent makers for patent infringement. It was said above that vents can not have moving parts, which is not true, "Smart Vents" are designed to remained in the closed position unit water reaches it, then they snap open. FEMA allows any vent that will automatically open without assistance. One example on the FEMA website was a piece of plywood hanging vertically (hinged at the top) to cover the opening. It was be allowed to freely swing both ways, to let water in and out.
On the subject of vent areas, my understanding is that if the vent is just an opening, it's 1 sq. inch per sq. foot of enclosure. However, if an engineer can test and certify a vent to see how much area is can actually cover. I'm sure there is some FEMA criteria as to how much flow per second, or whatever, the vent must allow. The 1:1 ratio is probably a safe estimate. Engineered flood vents almost always come up with great square footage coverage than their opening size would suggest.
I have been told to indicate the manufacturer and model number of the flood vent, then calculate the net area based on the manufacturers guide lines. I am not an engineer, so I just report what I find, and let the insurance companies/FEMA handle it.
I have contacted that engineer and am studying all the design data. It appears they have considered design principles that others have not. This will require a lot of study.
Paul in PA
This isn't a new concept. The "Smart Vent" has been around for years without a problem ... they show their opening as 8" X 16" (128 sq. in.) and their coverage area is 200 sq. ft.
http://www.smartvent.com/products/view/1540-510
That's what I've been doing the past few years.
I just have a hard time with a vent providing a higher flow rate than an open hole. 😛
I recommend you adhere to 44CFR60 (reference FEMA TB1-08) when completing an EC involving engineered openings.
If you don't allow for the certified coverage and go with the net opening you are doing a disservice to your client.