Originally Posted By: away This post was automatically imported from our archived forum.
All,
Reading the QOD’s brought to mind a conversation I had with my home builder’s warranty guy about the location of soffit vents.
He said that they cannot be within a certain distance above or to the side of an openable window since if there is a fire in the attic it may cause the flames to shoot out of the vent right at someone trying to escape through the window. I am no expert on how fire reacts, but it sounds credible to me.
My question is, Are there prohibited locations such as this? I checked my IRC (2000 version) but nothing was mentioned. Either I am looking in the wrong spot or it doesn't exist. Is there a fire code that could be involved?
FYI... Texas uses the IRC but cities can adopt their own codes. The city I live is a very small and doesn't even have a building department (just a zoning/permit volunteer committee) so I don't think they have developed higher standards than the IRC.
I don't think he was trying to snow me as we were discussing ventilation in general and not any specific concern I had.
Originally Posted By: rcloyd This post was automatically imported from our archived forum.
Andrew:
I have been involved in building code administration for over 16 years and have never heard of this requirement. I suppose it could be something written/adopted on the local level.
Originally Posted By: escanlan This post was automatically imported from our archived forum.
Hi Andrew,
It is interesting that you should bring that up. I too recently ran into a new home inspection where the builder made mention of soffit vent location under windows was prohibited. I checked the codes (IRC IBC NFPA etc.) and could find no reference to this. Also searched the WEB and no reference.
It could be a local code for some reason. You can check on many local codes at www.municode.com . But I could not find any reference to it in local codes either. As a doublecheck I went to Plano's local codes as they are one of the strictest and most developed codes sections. They did not mention it either.
As you said I too am not a fire expert and that could have credibility. But if so then I would expect building requirements to change preventing many windows on one wall that would also prevent venting from that wall area. The home I inspected had plenty of room for other vents in the soffit area. Unfortunately they chose not to place vents there and the home was significantly underventilated for normal applications. The home also has a gas furnace taking its combustion air from the attic so that exacerbated the ventilation issue.
If you hear anything let me know. I don't know if that is just another builder excuse or actual code.
Originally Posted By: escanlan This post was automatically imported from our archived forum.
By the way, the only real explanation I could find on the net was the possibility of flame spread from the flames shooting out a window and up into a soffit vent to the attic area causing faster spread. The shooting flames can be sucked up into the attic through the draft process.
That could be a credible argument for not putting soffit vents under windows. But, when you stop and think about it that would be valid in a huge home or multifamily type building with fire rated walls between units. If you have flames shooting out a window you have a raging fire to begin with. More than likely, if close enough to a soffit vent to be sucked in, it probably already penetrated the ceiling of the room and could already be spreading in the attic.
How about some comment from our firefighters out there. We could use some professional explanation on this.
Originally Posted By: away This post was automatically imported from our archived forum.
Russell/Manny,
When I couldn’t find anything in my IRC, I was thinking local as well but as I said the city doesn’t have a building department (only about 2k population). Shoot they don’t even have inspectors; they contract guys out of Ft. Worth.
Then I started thinking one of the fire codes as a possibility, but thanks to Manny's research that doesn't pan out either.
I have some stories about the code inspections, or lack thereof, that are too long to post here. I'll just say, I am just glad I watched my house from the ground up with about 15-18 rolls of 36 exposure film to document things.
BTW Manny, your interpretation (flames spreading to the attic rather than vice versa) makes me think I may have gotten it backwards. I have slept since that conversation.
Oh well the quest for knowledge continues. Maybe I will call the county Fire Marshall and see what he says as well as fire officials in Ft. Worth.
Originally Posted By: pdacey This post was automatically imported from our archived forum.
The only time I’ve seen a situation where soffit vents are not allowed is along a “Zero” wall. Here in SA, a house can be built right up to the property line. This wall would be the “Zero” wall. It can not have any penetrations into the living space, including the attic.
Originally Posted By: escanlan This post was automatically imported from our archived forum.
Hello Patrick,
I can see that rational. It is even covered in the IBC Section 7. The concept being if you start a fire in one structure the draft does not pull it into another structure. There is a lot of Zero Lot Line construction going on in the Dallas Burbs now. So close if you spit out your window you have to be careful. It can easily bounce back in your face!  
The home I inspected recently was at least 15' - 18' between the roof projections (overhangs). I really would like to have a code reference or interpretation by code officials for that. Just in case I run into the excuse again I can at least let the builder know exactly what was intended.
Originally Posted By: scieslewicz This post was automatically imported from our archived forum.
The only area in the IRC that may cover this would probably be section R302 (in the 2000 edition). This section covers location on lots and if you’re seeing single family homes built within feet of each other, this may be the section to look at. Otherwise, two family dwellings and townhouses are covered in section R321.
My jurisdiction used the BOCA codes several years ago for townhouses and the CABO codes for single family.
I'm pretty familiar with the IRC and have never heard of the soffit venting not being installed over bedroom windows. I will say that I often find that the fire separation between townhouse units is not complete because the framers very, very often forget to fireblock the eaves between units.
The best thing to do is check with the local fire marshal if there is no building department.
Originally Posted By: jmyers This post was automatically imported from our archived forum.
Lets face it. If you are at the time when you are trying to get out a window because the fire is burning your arse, I don’t really think the fire spreading to the attic is going to be the biggest of your worries.
If the fire is at that point, it is probably already in the attic somewhere else anyway.
Originally Posted By: escanlan This post was automatically imported from our archived forum.
Hi Joe,
I agree! I also emailed a large vent manufacturer and their design engineers and staff answered. They are not aware of any codes or reasons why a builder would not put soffit vents over a window. I also asked how that reason would be valid if continuous soffit vents are used under the eve.
It is interesting to note one soffit vent manufacturer out there is manufacturing a self sealing soffit vent for this type of situation. As Patrick stated his local code prevents soffit vents in zero lot line construction, which I am sure many probably do, and rightly so. The humorous aspect of a self sealing soffit vent is that even if the vent seals the fire has, at the least, significantly damaged the soffit covering anyhow and may have breached it. I don't believe a self sealing vent would really buy much time for you.
