Condo ugh! Use sprayfoam betwn crawl space joists?

[whatever419]

Situation: Attached 2-story, 20-year-old condo buildings located in south central Indiana (Bloomington), with 4 connected first floor units above approx. 1000 sq ft. vented crawl spaces approx 24" h. The crawl spaces are connected in pairs. A year ago we shared our pre-buy inspection report with the HOA. The main crawl space issues were that a lot of fiberglass insulation was hanging down and the vents needed to be repaired or replaced.

I assumed they would clean the place up and replace any batts that needed it. Instead, the HOA board contracted to have the spaces "conditioned" without seeming to understand the complexity of this particular situation. I raised questions here (www.inspectorsjournal.com/forum/topic.asp?TOPIC_ID=13017) and then with them. Eventually, I got an agent in the city Planning Dept involved, and he pointed out design problems and requirements for fire retardant barriers, dampers, etc. Unfortunately, by the time they paused in the process to reconsider their approach, the contractor had removed all the fiberglass insulation, installed a new vapor barrier (and probably removed the old one) and installed 2" rigid extruded polystyrene insulation on the exterior walls.

The city agent suggested 4 possible options. The simplest and probably least costly seemed to be that of sticking with the vented system. The board agreed, but informed me that they would use spray foam instead of batts. Sounds nice, but...

Possible problems that I see are:

* The HOA board seems reluctant to communicate with residents living over the crawl spaces (to determine or alert re allergy/health issues, precautions during application, etc.)

* I wonder if a thorough job can be done, applying this spray to a surface about 24" above the floor while lying down in an unlighted crawlspace.

* I read on another site that 2" deep spray foam might cost $2 sq ft. x 100 sq ft @ = $8k. The board has not said what the actual quoted price is.

I'd appreciate any feedback/opinions on proceeding from here.

Also, could I get clarification? - a former house builder friend has said that since warm air rises, the primary function of the insulation in the crawl between the joists is to avoid losing cooled air from the living space in summer, but that it doesn't do much to contain heated air in winter. Is this correct?

[hausdok]

He's right, warmed air rises; however, heat doesn't "rise" - it radiates evenly in all directions regardless of what the air does. Warm air rises because molecules in colder air aren't as buoyant and they settle, displacing warmer-thinner air upward.

If you warm the inside of a home, the heat wants to radiate outward evenly in all directions. That's one of the reasons that radiant heat in ceilings works and it's that knowledge that warm air rises that gives most folks the misbegotten idea that ceiling heat can't possibly work because it's, well, on the ceiling.

Heat moves from warmer to cooler. If you don't provide some insulation to temper the differences in temperature between the crawlspace and the interior, heat is going to migrate toward the cooler crawlspace and ultimately costs more in energy dollars.

ONE TEAM - ONE FIGHT!!!

Mike

[Jim Katen]

Situation: * The HOA board seems reluctant to communicate with residents living over the crawl spaces (to determine or alert re allergy/health issues, precautions during application, etc.)

With modern foams, there shouldn't be any allergy/health issues. At least not real ones. Of course as soon as the residents get wind of this, they'll begin to suffer all sorts of imagined maladies.

* I wonder if a thorough job can be done, applying this spray to a surface about 24" above the floor while lying down in an unlighted crawlspace.

It'll be unpleasant, but it's doable. In fact, it's probably easier than trying to reinstall fiberglass batts in that space.

* I read on another site that 2" deep spray foam might cost $2 sq ft. x 100 sq ft @ = $8k. The board has not said what the actual quoted price is.

Foam is expensive.

Also, could I get clarification? - a former house builder friend has said that since warm air rises, the primary function of the insulation in the crawl between the joists is to avoid losing cooled air from the living space in summer, but that it doesn't do much to contain heated air in winter. Is this correct?

Warm air does, indeed, rise. But the primary function of underfloor insulation isn't to prevent air movement, it's to prevent radiant heat loss. If the crawlspace is cold, indoor heat radiates from the floor to the crawlspace air. (Heat doesn't rise, it radiates equally in all directions.) Without underfloor insulation the vented crawlspace will suck heat from your buildings.

Your association has moved from making a really stupid decision to just making a costly decision. Simply replacing the fiberglass would have been much cheaper and given something close to the same performance. The owners won't see a payback from the cost of the foam for many, many years yet. And, of course, they've already paid out a bunch of cash to the first contractor.

- Jim Katen, Oregon

[whatever419]

Thanks. I think I understand the concept of radiant heat better now.

[whatever419]

Sorry for my sloppy typing. Correction; this should read:

I read on another site that 2" deep spray foam might cost $2 sq ft. x 1000 sq ft @ = $8k. There are actually 2 buildings, so this number would be $16k.