Spray on foam for a roof

It might not be a great idea. A municipal stadium (near Newport News, VA, if memory serves) had foam insulation on their roof, and the local fauna (seagulls) ripped it to shreds. It had, unfortunately, an attractive aroma. Fish oil in the paint, I believe, was the particular issue.

If this is a simple shed roof, with air circulation over and under, it won't benefit much from insulation anyhow. And, if there's no circulation underneath, it'll trap water and cause container rust (or worse, harbor skeeters).

A google search for spray foam insulation will turn up a list of companies selling the stuff, there are some options for slow rise (for filling walls), fire retardant, and I saw one anti-microbial. For the standard stuff prices seem to be $565-600 for a kit to do 600 board feet (600 square feet one inch thick, about R6). I checked on this a few years ago when I was thinking of doing the "ceiling" of my crawlspace and the prices were exactly the same but the crash put those kinds of spending plans on hold, sigh, so I can't recommend a particular vendor. FWIW,

seems to have decent instructions :-).

What does that two element spray on foam cost for about 1,000 sf? Want to shoot the underside of the roof over my containers for insulation, water shedding, and reflection of heat.

Steve

This sobered me up. I don't think I want to chance a bad foam job. Dead fish smell, eh? Lovely!

sensitivity isn't harmful? (from other links)

Pass!

-- The reasonable man adapts himself to the world; the unreasonable one persists in trying to adapt the world to himself. Therefore, all progress depends on the unreasonable man. -- George Bernard Shaw

I called a local insulation company about six months ago to request a price on spray-on insulating my crawl space. They said if it was "clear and unimpeded", they could insulate to R19 for $1.00-$1.35 per square foot (based on actual material utilization). I even asked about the clearance (22"), and they said that was not an impediment.

When I think about how hard I work to hang insulation, and how nasty job it is, that seems pretty inexpensive.

LLoyd

Last year, I paid about $4k for borate treatment, a vapor barrier, and

1,500s/f of R-30 Knauf Ecobatt in my crawlspace. They also drilled the exterior walls and sprayed in borates in the outer wall cavities.

It was worth it. Savings look to be a few hundred a year, but the comfort factor is wonderful. And the company belonged to my barter club, so most of the money was barter I had saved up. Yeah, it sure beat getting down there and doing it yourself.

I recommend doing the borates, too, to keep the termites at bay forever. It's well worth it. My last home had $6,500 worth of termite damage.

-- The reasonable man adapts himself to the world; the unreasonable one persists in trying to adapt the world to himself. Therefore, all progress depends on the unreasonable man. -- George Bernard Shaw

That's about 1/3rd the cost just to buy the spray foam to diy!

I called a local insulation company about six months ago to request a price on spray-on insulating my crawl space. They said if it was "clear and unimpeded", they could insulate to R19 for $1.00-$1.35 per square foot (based on actual material utilization). I even asked about the clearance (22"), and they said that was not an impediment.

When I think about how hard I work to hang insulation, and how nasty job it is, that seems pretty inexpensive.

LLoyd

"Carl Ijames" fired this volley in news: snipped-for-privacy@news2.newsguy.com:

FWIW, they use a bulk tank mixer apparatus on a trailer, and apparently can do this quite inexpensively. Their labor is almost nada... they do about

50sq.ft. per minute standing up, and I imagine they hire agile little Mexican guys (down here) to crawl around under houses on their backs.

They even gave me some references to check out.

LLoyd

I worked for a refrigeration company in Southern Louisiana that sold walk in coolers and freezers. They made them out of wood frames, metal skins, and a two element expanding foam shot into the molds. Hydraulic presses kept the pieces from bulging. A couple of times, mistakes were made, and the pressure blew the hydraulic presses from their floor anchorings.

They also offered the services of spraying the two element foam onto existing structures and refrigeration buildings, at a cost much less than replacement, particularly in older structures. It added a high r value also, which could convert a struggling box and system into an efficient one at a low cost. This foam skinned over with a hard shell, adding a water barrier to its benefits. One of the elements was methyl ethyl ketone, some fairly nasty stuff when aerosolized into the air, or even just skin contact. That was in 1976, probably before all this tree hugger falderal.

They had long wands that looked like a pressure washing rig, just two pipes going up to the spray nozzle. Aim, spray, and let it dry. They could do enormous areas in a very short time. Trick was to know how much it was going to expand, and spraying the right amount on there the first time. A one coat perfect spray was better than a seamed two coat spray. Overspraying just added a little weight, but more r value, and less of a profit.

Steve

Have an experienced contractor do the job - the DIY kit is NOT the same. The good stuff is sprayed and I believe there is heat involved - not sure if it is an exothermic reaction only, or if the stuff is heated as part of the application process. My Dad's last two houses both had spray foam - both done by the same local contractor. There are two big well-known contactors in the area that likely do 80% or more of the spray foam insulation in the area.

Microdyne had a contractor foam their three 40,000 square foot buildings, along with the two enclosed 50 foot connectors. The contractor brought several large trailer loads of 55 gallon drums of the two part foam, and worked for over a week to apply it. They had a few leaks where they stopped for each day and had to cut notches and fill them with more foam. The chemicals were photo degradable, and a lot of the employees took them home for recycling containers. Shipping had the giant can opener to cut the tops out of the drums without leaving a sharp edge.