72: Compressor Adventures 1

I have a small Craftsman compressor that puts out about 6 cfm. Okay says self, we need 4 more cfm and we’re all set. So, I google the subject “manifolding (connecting) compressors together” and I get several positive responses. The articles say it’s done all the time. So, I borrow a friends compressor (also a Craftsman , but a littler larger) and buy some air hose and fittings to connect the outputs together. Everything looks pretty slick. My compressor needs are solved for very few dollars. If only it could be that simple.

Long, story short, the foam doesn’t spray. I mash the trigger and the foam doesn’t even make it all the way down the mixing tube before it stops. Needless to say it doesn’t spray. Canister 1 is lost. I’m sitting there wondering what’s wrong (as the two components backflow and start mixing together inside the canisters). Remember this stuff expands when it mixes. I get the canister out of the gun and set it on the floor (bad move) – this is why you need box #2. It keeps expanding and eventually pushes the plunger partly out the back end of the canister. Now the unused part A is spraying all over the place, a stream of stinky, brown goo arcing 20 feet across the inside of my house, hitting walls, windows, window screens, my work table, darn near everything in sight. I finally throw a rag over it and pitch it all out the window, where it finally empties, but not before it has decorated the inside of my house with part A; the resin component that has a medium strong chemical odor.

So, it’s open up all the windows that weren’t already open and then off to the phone to call Soythane technical support. Fortunately, it’s a 1-800 number cause I’ve used it plenty. Tech support guy says he’s never heard of connecting two compressors together and that they use a Campbell Hausfeld 80 gallon 5hp 210 volt compressor for all their test spraying. Hey, that’s a big compressor, lots bigger than my tiny little Craftsman. How do I know this, because while I was looking for airhose and fittings, I also looked at all the compressors for sale at Lowes. Their biggest is an 80 gallon Kobalt for $799, but it only puts out slightly more than 10 cfm at 100 psi. Further, it says peak horsepower of about 5, but running horsepower of about 4. Self says, I don’t want to spend this much money, especially if it is going to just barely get out 10 cfm.

So, I call up the local rental place to see what they have in the way of compressors. Sure enough, they have this big mama; gasoline powered, 11 hp, Honda engine, with a pump the size of a beach ball. It puts out 25 cfm at 175 psi, so self says to self…problem solved. It’s so heavy that I’d never get it out of the pickup truck, so they deliver it to me on a truck with a liftgate. It goes for $215 per week (so much for cheap compressor solutions). I get it delivered that afternoon, expecting to spray foam the next day.

Learning opportunity #1 – the weather forecast the next couple of days is highs of 75 degrees. Shame on me for not checking the forecast first. Beautiful weather to work on a house, but not to spray foam because this stuff needs 80 degrees (or warmer) to cure right. In fact the company says use the 80-80-80 rule. 80 degree material temperature, 80 degree substrate temperature (the surface you’re spraying it on) and 80 degree air temp. Higher temps are okay, lower temps are not, better to wait for warmer weather. Great, the clock is running on this rental compressor and I can’t even use it.

But, somehow the planets align. The very next day even though it’s only 75 outside, the sun shining on my metal roof warms the metal up to a “comfy” 130 degrees. How do I know this, they recommend buying one of those laser infrared thermometers, about $30 to $50 at Harbor Freight or Sears. The roof warms the air inside the house up to about 85. Great, all I’ve got to do is warm the foam up to 80 and we’re in luck. Tech support gave me several ideas on how to warm canisters, but sitting them in the sun is the easiest. Hint: if you set them in the sun, they don’t need to be there very long. Five minutes is plenty, 15 minutes and they are at 95 degrees; too hot to spray foam with, as the foam will both mix and cure in the mixing tube at that temp, clogging the gun and losing yet another canister of foam. Use 90 degrees as a max for foam temp. Above that, cool them before use. Better yet, don’t leave them out in the sun too long. If the canisters are 80 – 85, go for it.

We have a ways to go yet, so I’ll continue in next post.

71: Soythane Foam

Soythane foam comes in double canisters, pic 1 and is sprayed with an air gun, pic 2. There are six canisters per case (about $140), each case is supposed to cover about 200 sq ft (foam 1" thick), so each canister covers about 33 sq ft. Cost wise this is about 70 cents per sq ft, about the same as method 2 in previous post and cheaper than method 1. The only equipment you need is a compressor capable of 10 cfm at 100 psi. For those of you who have never used anything larger than a small home size compressor, this turns out to be a rather large compressor. More on that later.

As I'm spraying the roof first, let's envision what that will look like. First, I'll be standing on a ladder or on a walkboard on scaffolds. I'm suited up in a full body suit (Tyvek), with goggles, respirator, rubber gloves, ear plugs, hat. The gun and a full canister weigh in at what I've been told is 17 lbs, though it feels heavier. Turn on the air to the atomizer and mash the trigger and spray out the canister contents in 45 or so seconds. Discard canister, load another, repeat.

Initially, I thought this canister idea was a little wasteful, and would likely result in this stuff costing more than it should. But, there are some nice advantages to this method of delivery. Foam doesn't go through the gun and there are no long (heavy) hoses full of foam to drag around or purge, clean up and stow at the end of the day. Unlike the Source of Supply method above, this system has been around for a long time, as this gun also gets used to spray bed liners in pickup trucks. So, this equipment has some history.

The company advises that if you're going for 2 or 3 inches of finished foam thickness, to do it all in one pass instead of three separate 1" layers. This stuff generates heat when curing and more heat means more expansion (thicker foam layer). Since I want about 3" thickness that means each canister will only be covering about 11 sq ft of area. My roof trusses are 4 feet apart, so I'll spray truss to truss by almost 3 ft per canister. Doing that much area, I can realistically do it from a stationary position on a ladder. Spray, move ladder, reload gun, spray next area.

You will want a table nearby with your spare cartridges, so you don't have to bend over and pick them up off the floor. You will use the table to screw the mixing tube on top of each canister before you put the canister in the gun and then attach the atomizer hose. You will also want a couple of empty boxes. The foam comes in boxes so you have plenty of those already. Box 1 is for the empty cartridges and box 2 is your emergency box to put malfunctioning cartridges in. More on this in next post.

70: DIY Foam Alternatives

After lots of research on the internet I chose Soythane foam for my insulation. Though they advertise it’s “green” because it uses soy as a major ingredient, that’s not why I chose it. So, why did I choose it?

First off – why spray the foam myself, why not hire it done? Pretty simple answer – cost – hire it done and we’re looking at $13,000 or so to do the whole house with 2 pound, closed cell foam. Do it myself and it will run about half that. $13,000 is more than half of all I’ve spent so far, more than a little sticker shock. And since I’ve built everything else, spraying my own foam seems like the right way to go.

For this to work for me there can’t be any really negative aspects related to equipment, delivery method or cost. The “propane tank” companies like Tiger Foam send your foam in tanks similar to the propane tanks you use with your barbecue grill. There is no equipment to buy or rent. You just hook up the hoses and start spraying. When through, throw away the cans, no hazardous waste to deal with. Disadvantage: cost. It runs about $1.00 per sq ft per inch of foam thickness. As I want about 3 inches of foam in my roof, that is more cost than hiring it done. Disadvantage2: your “pressure limited”. The cans come pre-pressured. If you lose pressure for any reason, the foam is lost, and that’s a $600 loss per set of cans. Other alternatives were cheaper on materials, so I ruled out the “propane cans”.

Method #2 - from a company named Source of Supply. They send you foam in 17 gallon drums or 55 gallon barrels. A 55 gallon barrel weighs in at around 500 lbs, so moving one around by yourself is pretty much out of the question. Because the barrel sets weigh over 1000 lbs total, you get into hazardous material shipping charges, which are not cheap. Equipment cost: you have to buy anywhere from $2500 to $3500 of equipment to spray the foam. The higher cost amount is for heated hoses. For my one-time, one-house use of the system, it would not be cost effective. For a home-builder or contractor who didn’t want to have to sub out his foam work, this might be a good system. Disadvantage2: To buy the system, the company requires you to pay for training, about $400-$800. From a safety standpoint I have no problem with the training. From a cost viewpoint, I do. Disadvantage3: This “system” has only been out on the market a couple of months. I wasn’t convinced they had all the bugs worked out yet.

Soythane, the method I chose will be discussed in the next post.

69 Spray Foam Insulation – Why?

So now it’s time to put the spray foam insulation up in the roof. This stuff is sorta like the spray foam you buy in cans at Walmart to plug holes and keep out water, bugs and unwanted airflow. Why use spray foam at all, or stated differently, why not just use fiberglass insulation like everybody else does. Answer: Metal roofs sweat. That sweat is condensation which occurs when moist air comes in contact with a cold (metal) surface and creates water droplets (same principle as drops forming on the outside of a cold beer can in the summer). If enough water drops form, it rains in your attic, which soaks the fiberglass insulation and dramatically reduces it’s ability to insulate - the same principle as wet socks make for cold feet, even if the socks are wool (a good insulator). I have read that damp fiberglass insulation has it’s R-value cut in half over dry insulation.

It also explains (at least to me) why in most houses the roof has 10 – 16 inches of insulation, while the walls have only 3 to 6 inches and the concrete floor has none (under the concrete). Don’t laugh, in really cold climates they DO put insulation under the concrete. Television marketing has conditioned people to believe “heat rises”, so they need to add insulation in their attic to prevent this heat loss and save money on their utility bills. Actually, heat flows in all directions equally, it doesn’t “prefer” one direction over another. When you condition people to think heat rises, then it becomes an easy sell to add more insulation in their attics where it’s easier to install as opposed to more insulation in their walls, harder to install. Taken to the logical conclusion, your windows (even the really good ones) lose more heat than most any even poorly insulated wall or ceiling. Isn’t advertising great.

So, how does spray foam keep it from raining in the attic? The simple answer is by keeping the moist air away from the cold metal. A longer answer is by insuring that all the surfaces inside the roof stay above the dew point temperature (where condensation occurs). I’m not going to delve any deeper than that into how, why and where condensation occurs. If you want to go deeper, check out buildingscience.com and start reading or get out your college textbooks on physics and thermodynamics because that’s where you are going to end up anyway. And let the record be straight, I barely passed thermo… with a “D” and was proud of it.

This post has veered way off direction, so I’m going to stop.