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Condo Conditioned Crawlspaces - Ventilation?


whatever419
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Our condo HOA has hired a contractor to condition the crawlspaces in our attached 2 story, 20 year old buildings located in south central Indiana (Bloomington). We have four connected first floor units that will be most impacted by the upgrade. The crawlspace below each unit measures approx. 1000 sq ft., but I believe all are connected via (just guessing) approx. 10' opening in support walls between units. The space below my unit is very shallow, approx. 16-24" high. So, rounding things off- 2000 cu ft under each unit x 4 units = 8000 cu ft total crawlspace.

A new vapor barrier is being installed over the old and blueboard insulation placed on the cinder block walls. Some sort of sealing is being done to the floor joists and exterior vent blocked off with blueboard.

In the middle of each first-floor unit, a gas furnace is in a utility closet which opens into the great room. It has a 6x12" floor vent into the crawl space to draw combustion air for the furnace. I was told by a worker, if they don't have this vent, one will be installed so that "air will circulate to the crawlspace." I don't understand this.

If our living space is always warmer than the crawlspace, how will air move down?

And if it did move down, would this small passive opening, be enough to take care of possible humidity/mold issues?

Finally, with the crawlspace being sealed from the outside, will there be sufficient air for the furnaces?

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Instead of drawing combustion air from the crawl, why not draw it from outside through a duct?

Conditioning the crawlspace is not a bad idea, but I think it should be monitored for problems such as moisture because of the closing off of the vents to the exterior.

An uninsulated floor will radiate some heat downwards. I learned that here. [:)] If there are heating ducts running thru the crawlspace, they will also heat the area.

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If the vapor barrier is installed satisfactorily, the vents sealed tight, and the area conditioned, there shouldn't be excessive humidity or moisture.

IOW, if you do it right, there's no need for "monitoring".

The entire installation should be engineered, meaning someone considering all the requirements. It sounds like the contractor is only thinking through 1/3 of the requirements.

You want to put some air into the crawl, you need combustion air, and neither of those needs will be satisfied by cutting a hole in the floor.

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Ah, you beat me to it. Heat loss from the ducts in the crawl and from the floor above don't make the crawl conditioned. It doesn't sound like combustion air was considered in the original design and was merely passable to begin with. And, am I the only one concerned about the fact that the crawls are accessible from one unit to the next? I always thought that fire separation in condos and townhouses was required to be continuous.

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You want to put some air into the crawl, you need combustion air, and neither of those needs will be satisfied by cutting a hole in the floor.

Hi,

Well, he sort of can. For a sealed crawlspace, if you have an unobstructed vent from the interior into the crawlspace at either end of the home, you will get naturally occurring convection and the air in the crawl will be conditioned. The rule-of-thumb requirement for combustion air is going to be 50 cubic feet per 1,000 Btu/Hr and by placing the proper size vents in that floor membrane and essentially making that crawlspace part of the conditioned interior, he might derive sufficient volume - between the total volume of air in the crawl and that in the house - to satisfy the combustion air requirement.

However, there are a couple of problems. The vents need to be located where they'll get plenty of air all the time and you wouldn't want to do this if the crawlspaces aren't isolated from one another because now any smoke, fumes and odors can pass easily from one unit to the next. I'm betting the guys in the middle will see their heating bills go way down and those in the end units will see them go up. Same thing in summer when the AC is used.

To do it, he has no choice but to build separating walls between units under the home, place sufficiently-sized vents in each unit in areas where they'll be unobstructed and have plenty of air, and he'll have to install well insulated fresh air intake ducting from each of those utility rooms to the outside.

It would make more sense to simply install intake ducting to the utility rooms and then seal the crawl and not open it to the interior. If he does a good job air sealing the crawlspace, insulating the exterior walls, tightly insulating all of the ducting and piping that passes through there and then carefully seals the barrier, he might end up with a very snug and dry box. Or not. Even if he did all of those things perfectly, there's the question of vapor diffusion. Without the ability to circulate air in there and to make that area part of the conditioned space of the home, vapor diffusion could definitely be an issue.

Then there is the question of quality of work. Getting someone to do all of this correctly while lying on his or her back in a dark hole requires a huge leap of faith. Unless he's right there watching his workers closely, and they understand how every element has to work together in order for this to work, and are themselves dedicated to seeing it work, you know they're going to be taking shortcuts when the boss isn't looking.

I agree with Kurt; he needs an HVAC engineer in there that understands the dynamics of sealed crawlspaces to show him what to do, or he's going to create more problems than he's going to fix.

Tell him to go here and study his butt off and then ask himself if he feels lucky.

ONE TEAM - ONE FIGHT!!!

Mike

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I will stand by my comments above. If the conditioning is not done right, good chance, the only way to know that there are problems will be for someone to check the crawlspace regularly.

And a two foot crawlspace can be quite warm and dry from heat loss from above. The key is to prevent moisture from accumulating down there.

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Well, stand away. It's the standard approach of most contractors, and the reason why I have a business.

I've yet to see problems accrue from work performed satisfactorily. I like to do the job the way myriad credible studies and engineering reports (and my own experience) indicate is the right way, and do my standing and looking where the view is prettier.

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John,

Sometimes it's best in this forum environment to defer to the "local" guys. Your comments are probably on the money for your area, but have you ever been to Bloomington, Indiana? The frost line where you and I are probably extends only about a foot below the surface. I'm pretty sure it extends about four feet below the surface in that region. That means a crawlspace there is an icebox - why do you suppose they prefer basements in that part of the world?

Lots of unpleasant things can occur in a crawlspace when winter ground temperatures are what they are in Indiana. Where you and I can get away with insulation on the underside of the floors over crawlspace in our region, in that region they find themselves needing to insulate the walls of the crawlspace just to be able to keep heat in homes.

It's something to keep in mind when tossing out an opinion where an uniformed non-inspector or non-contractor might misconstrue what you've said.

ONE TEAM - ONE FIGHT!!!

Mike

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Roger that, Mike. Just trying to help. Somehow I doubt my remarks will sabotage the project. [:)]

Your comment about the guy laying in a 2 foot cavity lends some sense of realism to the job, doesn't it?

Yep, I'm reminded of it every time I look at the new wallpaper on the site.

ONE TEAM - ONE FIGHT!!!

Mike

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Clarifications & News:

Turns out our crawlspaces are connected in pairs (not all 4 together).

Vents will not be cut in floor, but don't know if they intend to cover existing ones (we got a new furnace & our vent was sealed and a pipe installed directly from combustion chamber to crawlspace).

A duct will be installed on the plenum of each furnace to direct heated/cooled air into crawlspace. I don't know of any plan to replenish extra air required for this.

OwensCorning FOAMULAR 150 2" rigid extruded polystyrene insulation is being installed.

The ducts in the crawl are flex type (don't know about insulation).

I am awaiting info on local regs re connected crawlspaces...

Re quality of work: Just gonna say some of these folks don't look like they have much experience. [:-weepn]

Needless to say, I have more questions about heating the crawlspace - especially since it connects to my neighbor. The mgmnt company rep sent me "conditioned crawlspace" info that extolls the advantages of (essentially) heating our floor. But since our floors are probably osb or plywood and covered with carpet, how much good is it going to do for the living space?

Thanks for all the input - a great help.

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Pre-Thanksgiving UPDATE:

We learned for the first time from a worker that a duct would be installed to the plenum on the bottom of our furnace to supply conditioned air to the crawl.

Email reply from county buildings department:

* "Apartment construction allowed crawlspaces to be connected assuming that the floors over the crawlspace had a one hour floor/ceiling assembly..."

* "combustion air grills should be fitted with a fire damper"

* "foam plastic insulation shall be protected against ignition..." (I have heard fire-retardant paint will be acceptable)

* crawl "shall be continuously supplied with a minimum of 1.0 Cubic Foot per Minute of conditioned air per 50 Square Feet of under floor space"

* "No permit is required."

Question to forum:

Apprx 1000 sq ft crawlspace- so, 1 CuFt x 20 = 20 cu ft/min? How do I find out if our furnace/AC is delivering this?

We have a newly installed Bryant Evolution System Plus 95s Gas Furnace. Some (most?) of our neighbors will have 19 year old, less efficient furnaces.

We met with 3 members of our HOA board re the crawlspace remediation -

Q: Who is the designer/expert of the crawlspace modifications?

A: A professional crawlspace remediation company submitted a line item bid. It was very high. They copied the line item list and submitted it to (2?) other companies.

Specific questions about the design (how return air would get back from the crawlspace to the furnaces, etc.) were met with the same answer: The work is being done properly and "according to code."

Q: Are you going to ask the other owners for permission to alter their plenum/heating system?

A: No response.

Their basic reply to these type questions was that the crawlspace upgrade was approved at the July membership meeting. That no minutes have been distributed and that numerous members missed the meeting did not appear to concern them.

This job apparently does not require inspection by building department, but (we think) the HOA agreed to ask if the department would be willing to do it if asked.

We said our concern was about whether our furnace would still work efficiently and also concerned about the quality of the air we will be breathing.

Sorry if I haven't addressed all questions posted here (figgered this post was overly long already).

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These are connected crawlspaces with vents opening into the houses, right? That means if your neighbor is smoking the foulest of the foulest cheap nickle cigars you'll be smoking them too.

If you have a neigbor who is a Korean and is making kimchi, and you are one of those people that just can't abide the odor of kimchi, you'll need to get used to it, 'cuz you'll be exchanging crawlspace air with the neighbors and that smell will travel into your home.

How about airborne contagions? If one person catches the flue and is weezing and coughing and dumping all of that bacteria in the air, isn't some of that liable to end up being carried on the air into your home?

It sounds like you'll be heating the crawlspace with your hard-earned dollars. Is everyone going to be doing the same thing? If not, is everyone else going to pay you for the energy you lose to heat that crawlspace?

This systems makes about as much sense as a screen door on a submarine.

ONE TEAM - ONE FIGHT!!!

Mike

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Don't have the code section in front of me (watching MNF), but we can't have intermingled forced air systems. Can't have a single furnace serve two apartments, can't have return air from another unit, etc.

Contaminants in one apartment can transfer to other portions of the building. Can't have that.

What's the NFGC that says you can't do what they're going to do?

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Frank, I haven't responded to this thread because it hasn't made any sense to me. With every post, the information you present gets more & more bizarre. If you didn't seem so earnest, I'd guess that you were putting us on.

The scheme that your association is implementing is simply stupid. There is nothing about it that makes sense. I don't know where to begin in terms of describing exactly how stupid it is, but if the continuum of stupid was represented by the Empire State Building, your association's plan would be way up there on the observation deck.

Just so that I can fully appreciate the girth of stupidity at work here, let me ask a few questions:

1. Why are they doing this? What do they hope to achieve? If the goal is to save money, do they have accurate estimates of how much will be saved and what the payback period is? My guess is that the payback period will be, um, let's see, NEVER.

2. Has anyone investigated the history of water entry into the crawlspace? And I mean any water entry, even one tablespoon ten years ago. If there is evidence of past water entry, has anyone done anything to deal with this issue? If not, you're at risk of ending up with a stinking, moldy, mess.

3. Has anyone bothered to do radon testing of the buildings? Because if there are detectable levels of radon there now, they *will* go up after you incorporate the crawlspaces into the indoor conditioned air. The time to install a radon mitigation system is *before* the new vapor barrier goes down, not after.

4. Have you gotten references from the people doing the work? Have they done this for other HOAs? Were the results spectacular? Can you go look at the other jobs that they did 10 years ago to see how they're holding up?

- Jim Katen, Oregon

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[br

Q: Who is the designer/expert of the crawlspace modifications?

A: A professional crawlspace remediation company submitted a line item bid. It was very high. They copied the line item list and submitted it to (2?) other companies.

Love this. "We got a professional to design it but then we stole their design and asked a couple of cheapies to copy it"

I wonder what the professional crawlspace remediation company thinks about this situation.

Perhaps you should ask them.

-

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Frank, I haven't responded to this thread because it hasn't made any sense to me. With every post, the information you present gets more & more bizarre. If you didn't seem so earnest, I'd guess that you were putting us on.

I am so happy you decided to jump in - gave me the best laugh I've had since I stuck my nose into this "project."

Ahhh... where to begin? OK, first try to understand: I am not in the loop and the board ain't too happy I asked questions. See, I know almost zilch about HVAC and houses, but I tend to scratch my head when things don't seem logical.

Anyway...

when we were buying our unit, we had it inspected (radon tested also) and **our** crawl was found to be dry, but a lot of insulation between the floor joists had fallen down. We told the HOA, they asked for the inspection report, and almost a year later they start work without ever consulting me and the other unit owners who will be affected. Naively, I assumed they would clean up the crawl, lay down a new vapor barrier and put the insulation back in place.

Since I was not consulted or informed, I don't know when they decided go for the "conditioned" space, but I assume the first company they called in sold them on the idea. As I mentioned earlier, it seemed they took the first bidder's **line item list** and submitted it to one or more competitors. When this thing came to my attention, I had concerns and simply wanted info. I think I asked about the combustion air register (before I understood that "conditioned" meant they would be using my furnace to warm the space)... it sounded like they expected the house air to drift down through the register and I thought about warm air rising, etc. and was confused. When I asked the one guy on the board who I thought would have an informed opinion, he seemed to think it was obvious and told me that they had hired pros and I shouldn't worry. He also "didn't know" if he had a combustion air register next to his furnace. This answer did not inspire confidence and I continued asking questions and am now considered a nuisance.

At one point, I asked our mgmnt company, "Where is the plan"? I don't know what kind of plan I expected, but it turned out all they have is a contract that simply lists the tasks they would do. An ignition barrier was not on the list. I knew from my web trawling here and elsewhere that a barrier was probably required. The inspector confirmed this and later informed that the fire dampers would also be needed. (BTW, they would not send me a copy of the contract, but read to me on the phone.)

Wrapping up:

There will be an inspection, so they will have to do it right. I don't know yet if the board will inform the other owners that air will be directed from their furnaces into the crawl. I have told them they should do this, but whataya gonna do?

I know nothing about the other crawlspaces, units, etc. I have no clue about the competance of the company doing the work. I am, at my wife's urging, trying to think positive (or at least: let go of this thing), but they don't look real professional. (sigh) [;)]

Thanks for everyone's feedback. Happy Thanksgiving!

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The association members sound like a bunch of morons.

Understood. But a bit harsh. Unfortunately, our HOA is quite small, so there is not a large pool from which to draw volunteers. I think they simply know little about the subject, tried to save money (when I pushed the board to notify the affected owners about the project, one brushed it off, saying that all members are interested in hearing is that their dues won't go up), and trusted in the "professionals" they hired.

My wife has reminded me that it could be that folks who live in condos are probably less likely to know about repairs, etc. than others. They had asked me to fill a vacancy on the board before this meltdown, but I was looking over their D & O liability insurance and thinking they might not be carrying enough, so... Well, they probably don't want me now anyway.

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The association members sound like a bunch of morons.

Understood. But a bit harsh. Unfortunately, our HOA is quite small, so there is not a large pool from which to draw volunteers. I think they simply know little about the subject, tried to save money (when I pushed the board to notify the affected owners about the project, one brushed it off, saying that all members are interested in hearing is that their dues won't go up), and trusted in the "professionals" they hired.

My wife has reminded me that it could be that folks who live in condos are probably less likely to know about repairs, etc. than others. They had asked me to fill a vacancy on the board before this meltdown, but I was looking over their D & O liability insurance and thinking they might not be carrying enough, so... Well, they probably don't want me now anyway.

If there's one thing that rubs my fur the wrong way, it's when someone does a job badly and then weasels out of resposibility with the excuse that they're a "volunteer." As if it's the lack of pay that's somehow lowered their IQ.

Your board has screwed the pooch with this one. They're incompetent. If you find that you're ignorant about a subject, you don't forge ahead anyway. You find an advisor to help guide you. Your board needs a competent advisor who has no financial interest in the work. That's how intelligent condo associations do things.

I think your wife's observation is spot on. Maybe she should be on the board. After all, when lost, women tend to ask for directions. It's the men who drive further into the woods.

- Jim Katen, Oregon

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Condo association members are not morons; they are folks that are otherwise smart and intelligent, but choose to come together to make bad decisions collectively about their property.

Invariably, there are personality types......there's always a Capt. Queeg, a mutineer, someone with an uncle that's an architect, and a lot of ostriches. There's a process wherein you disarm all the disaffected members and get them on board, but you can't get there being quiet and nice about it.

If you don't want something stupid to happen, which sounds like it already is, you really need to step in and force the issue. Everything is wrong; feel confident of that as you yell at your brothers and sisters on the board. Doesn't matter if it's volunteers or paid employees; wrong is wrong.

About 20% of my business is HOA consulting. Trust me; you need to stop the presses until this thing gets ironed out. If you don't, you're going to waste a lot money.

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If I were a resident and the board wasn't listening to me, I think I'd simply hire an attorney and get an injunction from a judge to stop the work until an expert can be consulted.

ONE TEAM - ONE FIGHT!!!

Mike

I think that's about right. They really need to stop the presses; they're going down an expensive trail of confusion.

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I've gotten quite a few gigs some years from property management firms working with H/O associations. Many times my task has been to figure out how to fix something that got really screwed up. The screw-ups began when they were convinced to do something by contractors they blindly believed. The other times I've been brought in have been for litigation.

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