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    Air Infiltration/Exfiltration in Attic Space

    Air Infiltration/Exfiltration in Attic Space

    New postby rcwaszak on Tue Dec 29, 2009 3:25 am

    A friend just purchased a newly built condo in a 3 unit building and is experiencing cooking odors from one of the other units (3rd unit is not yet occupied). The living units have separate gas forced hot air furnaces and each living unit has a separate gas water heater located in a utility closet which has a single fresh air intake that vents to/from the ventilated attic space over each living unit. The attic spaces are supposed to be firewalled and built to "code".

    1) I have examined the attic and found some areas of the firewall that need to be sealed but I'm wondering what the code says about odor penetration.

    2) All the living units have "air-tight" recessed lighting cans - how effective are they at sealing out odors from penetrating the attic space?

    3) In the living unit in question there is a draft from the attic space into the utility room when the heating fan unit is running; this could be the possible souce of the odor infiltration.

    Note that this is a very large development by a large well known builder and has a one year "guarantee".

    My question: What can I do to make certain that the construction people will properly address this issue? My concern is that they will make a minimum effort rather than investigating and fixing the problem.

    Thanks, RC
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    Re: Air Infiltration/Exfiltration in Attic Space

    New postby Jerry Peck - Codeman on Tue Dec 29, 2009 7:11 pm

    Your condition and description of it brings up several interesting possibilities and arrangements.

    Being as it is a "condo" that means it is "one structure" and the "condo" is typically only 'the space' within that structure, with the structure being a common structure with all other condos.

    Are the condos side-by-side-by-side like townhouses extending from ground floor to the attic, or are the condos stacked one-over-another like you would find with apartments? Having access to an attic creates other potential 'not-good' aspects to your description.

    Each design has its own intricacies and requirements, both require fire separation, only in different places.

    The codes do not regulate "odor" per se, but the air which transmits the odors would not be intentional and would be intentionally unwanted.

    Would you fill in the blanks and describe the building the condo is in, and whether it extends from ground floor to attic or is stacked one above another?

    That information will help eliminate some potential 'what ifs'.
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    Re: Air Infiltration/Exfiltration in Attic Space

    New postby rcwaszak on Wed Dec 30, 2009 1:55 am

    Thanks for your reply Jerry.
    Let me see if I can verbalize a picture of this building. It is a 2-story structure consisting of 2 vertical living units backed by 3 double garages with a living unit above the garages. Another way of picturing the structure would be to visualize 3 double garages connected side-by-side with two 2-story living units behind the garages and the 3rd living unit above the garages.

    The unit we are talking about is the one over the garages. This unit has 9-foot ceilings and an attic space high enough to stand in with room to spare at the peak. The gas forced air furnace is installed in the attic space. The gas hot water heater is installed in a 2 1/2 x 3 foot utility closet on the living level and has combustion gases vented through the roof via 4" pipe; the ventilation air is via a single 6" pipe exiting the utility room near the ceiling and terminating in the ventilated attic (I'm not thrilled by this but I have seen where it is acceptable per code in some areas and I'll check it specifically for my location.)

    I will have the "warranty" people here to check all this out but I want to know what I can do to better my chances of getting things fixed correctly. Should I hire a private inspector to do a thorough check of the HVAC system ("smoke" test and whatever else he can do) and the structural workmanship to ascertain the cause of the infiltration? Or, trust that the "warranty" people will take the time to get it right?

    thanks, rc
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    Re: Air Infiltration/Exfiltration in Attic Space

    New postby Jerry Peck - Codeman on Wed Dec 30, 2009 9:35 pm

    Hi RC,

    Okay, now that I understand the configuration, I'll go back to your first post and questions, and try to add some other information and insight into what should be there, and, what should not be there.

    rcwaszak wrote:each living unit has a separate gas water heater located in a utility closet which has a single fresh air intake that vents to/from the ventilated attic space over each living unit.


    As a "condo", and the configuration you described definitely makes it *not* a "townhouse", those were required to be constructed in accordance with the International Building Code and not the International Residential Code (I am making a presumption here that the International codes have been adopted in your area - what city and state are you in, I may be able to find a local inspector I know and communicate with to do an inspection on the condo). The reason the Building code is used and not the Residential code is that the residential code ONLY applies to one- and two-family dwellings and townhouses - of which the structure you are describing is not one of any of those.

    Basically you have a common structure with the owners of the two two story units owning the interior space of their respective two story units, and your friend owns the interior space of the unit located over the three garages. As can be seen, the actual structure does not belong to any one owner but to an association of either all three owners or with a master association of the developement being the owner of the actual structures (the structure your friend's unit is in and all the other structures in the developement).

    The association is responsible (right now the builder is, but the association will be when the builder turns the operation of the association over to the association and the owners then become responsible for the association and the structures as well as all common areas) ... the association is responsible for the actual structure, the unit owners really only "own" "the space" within the walls enclosing their units. Most condos are set up such that the owner "owns" "paint-to-paint", i.e., the drywall belongs to the association as the drywall is "part of" the structural aspect of the structure (fire resistance rating, etc.).

    It is important to understand that the unit owner *does not own the structure or any part of it* (in most cases with condos) as that distinction is what rules everything else which is allowed or not allowed.

    I'll leave this post on that thought to avoid making this post any longer.
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    Re: Air Infiltration/Exfiltration in Attic Space

    New postby Jerry Peck - Codeman on Wed Dec 30, 2009 9:56 pm

    Hi RC,

    To continue, and with the knowledge that the unit owner only owns the interior space of their unit, I will try to answer your questions.

    rcwaszak wrote: 1) I have examined the attic and found some areas of the firewall that need to be sealed but I'm wondering what the code says about odor penetration.


    While the code does not address odors, the odors are being carried in the air, which seems to be circulating into areas which the air should not be circulating (if there were a fire, the smoke would be going the same places, and that would not be a good thing).

    Because the condo owners do not actually own any of the structure, the structure should be protected from the condo owners activities, meaning that no owner should have access to the attic space without going through some fire-resistance rated attic access opening in a common location as the attic over each unit *should* be part of the structure and not part of the unit.

    If each unit were to be sealed off from the attic, no air would be migrating around as you describe.

    Now, I have seen some condos constructed where the attic was part of the unit, but what that required is protection (fire-resistance rated separation) of the structure from the unit so that the structure (which is common) is not exposed to the wayward accidents of the unit's occupants, i.e., one would *not* want a careless unit owner to store stuff in the attic which causes the attic to catch on fire, and the attic, being common property, leads to the total destruction of the structure by fire, taking the other units with the unit at the cause of the problem (cause of the fire).

    That means one would not be able to see the wood trusses, etc., in the attic as they would all be protected behind a fire-resistance rated protective covering, such as gypsum board (drywall).

    2) All the living units have "air-tight" recessed lighting cans - how effective are they at sealing out odors from penetrating the attic space?


    Air-tight recessed lights are fairly tight, but not "air tight" as the word implies (albeit mostly so). Installing a recessed light of any type into a fire-resistance rated ceiling with the attic above would mean a 5-sided box would need to be built over the recessed lights to effectively take the fire-resistance rated membrane (the ceiling) up and over the lights, and that 5-sided box would then make them truly "air tight".

    A "5-sided box" is just that: take a "box", which has 6 sides (think of a dice) and remove one side, leaving an open box on that one side, that opening is now placed down over the recessed lights, with the box covering the recessed lights, however, the 5-sided box and the ceiling need to be made so they stay together, with framing behind the box and attaching it to the ceiling (will not do any good if the box were to move during a fire), and the box and ceiling need to be taped and sealed together as one - basically imagine seeing it during construction before the recessed light was installed and you would be looking at the ceiling with an opening up into the 5-sided box, into which the recessed light is then placed afterward.

    Sound complicated? It is.

    3) In the living unit in question there is a draft from the attic space into the utility room when the heating fan unit is running; this could be the possible souce of the odor infiltration.


    That combustion make up air vent into the attic is a problem, not only is it most likely *not* adequate for combustion make up, but it is communicating the interior of the condo with the structure's attic, which should be separated from each other with a fire-resistance rated membrane (gypsum board).

    My question: What can I do to make certain that the construction people will properly address this issue? My concern is that they will make a minimum effort rather than investigating and fixing the problem.


    Give my your city and state, and which codes are in effect in your area (the International Building Code may have amendments altering various sections of it) and I can also see if there is an inspector I know near you do inspect the condo for your friend.
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    Re: Air Infiltration/Exfiltration in Attic Space

    New postby rcwaszak on Thu Dec 31, 2009 2:57 am

    (RC, I apologize for messing your post up, I thought I was quoting your post for my post below and some how got into the edit mode from being the administrator. My apologies. Below is what I quoted, the rest I inadvertently deleted as I thought I was making a new post in response.

    Yikes! Again, I apologize.

    If you would, click on edit and correct as much of the information below as you can remember. In the process of my error I deleted your city, but I remember you were in Colorado.)

    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

    I believe the plans show the ceiling being one-hour fire-rated; would non-enclosed, "air-tight" cans satisfy that requirement?

    I've looked at the architect plans for this place and they call for the standard one vent high, one vent low (both through the roof) in the confined space of the water heater closet.

    However, I have seen code references (via web searches) regarding a single high vent terminated in a ventilated attic space.

    Is a builder required to meet all requirements specified on the architect's drawings or can the builder make modifications as long as the various local codes are met?
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    Re: Air Infiltration/Exfiltration in Attic Space

    New postby Jerry Peck - Codeman on Thu Dec 31, 2009 8:43 pm

    rcwaszak wrote:Hi RC,
    I believe the plans show the ceiling being one-hour fire-rated; would non-enclosed, "air-tight" cans satisfy that requirement?


    No, either the recessed lights themselves would need to be 1-hour fire-resistance rated or have a 1-hour fire-resistance rated enclosure over them (the five sided box).

    Additionally, if the ceiling is 1-hour fire-resistance rated (which is what I was presuming) then the attic access would also need to be 1-hour fire-resistance rated, and storage in the attic would not be allowed (otherwise the storage could be the cause of the fire the 1-hour fire-resistance rated ceiling is trying to protect the roof structure from).

    I've looked at the architect plans for this place and they call for the standard one vent high, one vent low (both through the roof) in the confined space of the water heater closet.


    That's because the ceiling is 1-hour fire-resistance rated. The combustion air ducts would be at least 26 gage steel and have 1-hour fire-resistance rated penetration firestops at the ceiling.

    However, I have seen code references (via web searches) regarding a single high vent terminated in a ventilated attic space.


    That is allowable ... but only under certain conditions, and violating a 1-hour fire-resistance rated ceiling is not one of those conditions. Now, IF the ceiling was not fire-resistance rated, then you could use the one-permanent opening method for combustion make up air as long as the opening meet the requirements for that method:
    - From the 2006 IRC. (bold and underlining are mine)
    - - G2407.6.2 (304.6.2) One-permanent-opening method. One permanent opening, commencing within 12 inches (305 mm) of the top of the enclosure, shall be provided. The appliance shall have clearances of at least 1 inch (25 mm) from the sides and back and 6 inches (152 mm) from the front of the appliance. The opening shall directly communicate with the outdoors or through a vertical or horizontal duct to the outdoors, or spaces that freely communicate with the outdoors (see Figure G2407.6.2) and shall have a minimum free area of 1 square inch per 3,000 Btu/h (734 mm2/kW) of the total input rating of all appliances located in the enclosure and not less than the sum of the areas of all vent connectors in the space.

    You stated that the vent is 4 inches, which means the minimum size of the vent is 4 inches or greater if need be based on input rating of the appliance. Let's presume the water heater has a 75,000 Btu/hr input rating, in which case combustion make air vent would need to be 75,000/3,000 or 75/3 = 25 square inches. You stated the combustion make up air vent was 6 inches, which is 3x3x3.14=28.26 square inches, which meets the minimum.

    The problem now become that the vent terminating in the attic violates the fire-resistance rating of the ceiling.

    Is a builder required to meet all requirements specified on the architect's drawings or can the builder make modifications as long as the various local codes are met?


    Yes, no, yes, and maybe ...

    Yes. The builder is required to construct in accordance with the approved plans.

    No. The approved plans are required to meet the local codes at a minimum and may well exceed the local codes (codes are minimums) and not make changes unless submitted as plan revisions and approved by the building department.

    Yes. If the plans do not meet minimum code, the inspector can catch the errors during construction and the construction will need to be changed to meet the code as a minimum - and as approved by the building official if there is a conflict between the inspector and the builder. The builder is also allowed to make changes to meet minimum code if the plans are wrong, but would be required to submit revised drawings for approval.

    Maybe. If the project is a large project, the building official may work with the contractor and let them make changes for incorrect plans during construction as long as an as-built plan is drawn and submitted for approval before final inspection or certificate of occupancy.[/quote]
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    Re: Air Infiltration/Exfiltration in Attic Space

    New postby rcwaszak on Fri Jan 01, 2010 3:20 am

    Thanks again Jerry,

    The location is Arvada,Colorado 80007 (just northwest of Denver); if you can refer an experienced inspector we might need some help in dealing with the "warranty" repair people.

    I won't try to reconstruct my last post - not too sure what I had written. I was talking to the on-site construction supervisor today and he seemed concerned about the ventilation issues. We shall see how he addresses the problem.

    One (big) thing that I forgot to mention was that this place has a fire sprinkler system which probably impacts the fire ratings. Can you shed any light on that?

    Thanks and Happy New Year, rc
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    Re: Air Infiltration/Exfiltration in Attic Space

    New postby rcwaszak on Sat Feb 20, 2010 5:21 pm

    Actions taken over last 6 weeks:

    1) drywall crew taped and mudded attic space; not an easy task in a completed structure.

    2) I weatherstripped utility room door and threshhold.

    3) I sealed all accessible joints on attic-installed hot air furnace.

    Results: air quality better, BUT still detect some cooking odors from other unit.

    Not sure what to do next:

    1) get used to it.

    2) have HVAC people come in and redo furnace connections.

    3) move . . .

    4) open to other suggestions.
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    Re: Air Infiltration/Exfiltration in Attic Space

    New postby Jerry Peck - Codeman on Sat Feb 20, 2010 7:54 pm

    rcwaszak wrote:Not sure what to do next:

    1) get used to it.

    2) have HVAC people come in and redo furnace connections.

    3) move . . .

    4) open to other suggestions.


    Now that the major and obvious stuff is done, have someone come in and do a blower door test, they should be able to locate where the leakage into your unit is coming from.

    With their results, the builder should be able to completely separate your unit from all other units, which should have been done during construction - EACH unit should be completely separated from every other unit regarding air flow and smoke movement (smoke moves with air flow).

    Odors, once your unit, and hopefully all other units, are completely sealed from every other unit, then you will be down to the odor which permeates through building materials, or which permeate or flow out into common areas such as when a door is opened, and then permeates or flows into other units. That odor level should be minimal. When all is done and the odor level is more than minimal and you cannot do 1) above (which should be easy to do with a very low odor level), and you've already addressed 2) in curing what the blower door exposes, then this is 4) and you are left with ... 3).

    Hopefully your problems will be solved long before you get to 3).
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