My Spray Foam Insulation Project

This spray foam insulation project is part of my green home retrofit that I have been documenting in these pages. Insulation is by far the biggest part of that entire project -- that's why I have devoted several pages to it.

I hope that by providing this much information I will help you be really well prepared to face your own foam insulation project.

Be sure to check the links to the various kinds of insulation that I have used in my house; they're at the bottom of the page.

And if you have any questions about this page, contact me.

Urethane Spray Foam, Step-By-Step

Urethane spray foam is the kind of insulation that people are most curious about, because it's relatively new.

Until recently, it seemed financially out of reach -- but as the cost of energy rises, it is becoming more of an investment than a luxury.

The more general part of this home insulation process can be found at my Insulation page. If you haven't visited it, I encourage you to do so. There's a lot of information there that you will find useful if you're embarking on a home insulation project for your property.

Preliminary Work


Before making the final appointment with the spray foam insulation contractor, we spent several weeks getting ready, especially in the following areas:

  • Removal of dust, residues, nails, etc.
  • Caulking and gap filling
  • Support work

For dusting, we found the best way was with our good old wet/dry vacuum. It was very efficient on the cobwebs.

This is a mere sampling of what was behind all the walls and ceilings.

How did the dust get there? It's a mystery!

No dust bunny escapes this shop vac and its operator, even it if means perching himself precariously over the void.

Luckily, there were no accidents.

PLEASE DON'T DO THIS! Use the right kind of ladder or scaffolding.

If you're going to spray the crawl space walls, you need to clean them well too.

Don't forget to dust the ceiling, out of respect for the spray foam operator.

(The floor looks dirty because it's... well... dirt!)

This is the dust that came out of the gutted walls and ceilings.

How on earth did it get in there?


The kitchen-dinette cathedral ceiling had a gap which needed
to be filled before applying the spray foam insulation.

A short piece of lumber was
used to fill that gap because
the "barrier" had to be
continuous to keep the foam
up in the ceiling, where it belonged.

The small spaces created by rebuilding the walls or the roof, as above, were filled with pieces of OSB, but small gaps appeared due to irregularities in the structure.

We used tube after tube of caulking to fill these flaws.


This is the rigid foam insulation which would be used in the floor
of the sunroom-office, which
sits directly over a plain
concrete pad.

To get a nice clean, shred-free
cut to fit the space, a table saw turned out to be the best tool.

Rigid foam in the ideal choice for a potentially damp situation, as it's the only waterproof insulating material, and there had been problems with moisture there in the past, as we discovered when we took the old floor apart.

In order to keep the rigid foam from resting directly on the concrete pad, small ledges were attached to the sides of the floor joists, for the panels to sit on (where red arrows point).

Three inches of spray foam insulation will be added on top of those panels.

The arrow points to a six-inch space that we left along the outside perimeter of the room so that it may be filled completely with spray foam later.


Lastly, don't forget to protect anything valuable or vulnerable against spray foam insulation fallout! Like electrical outlets (photo), windows, floors, furniture, etc.

The Big Day!

It's a foggy Fall day and the insulation truck is here at last!

It's really a small factory on wheels... a factory run by an alien, it seems!


The white foam being used here is the low-density (1/2-lb) type manufactured by Home Foam. It's polyurethane-based and water-propelled.

We started with the kitchen-dinette.

The arrow points to caulking referred to above -- essential to keep foam from escaping through gaps.

Painter's tape has been applied over electrical boxes, to protect them.

NOTE: the pipe shown here is a vent pipe. Do not ever place water pipes right against an exterior wall, then encase them in spray foam! That's a sure way to have them freeze in winter!

This is what the walls look like after spraying and before trimming. This type of foam expands so much and so fast that it's impossible to contain it...

... that's why it gets trimmed with a hand saw, the kind used for sawing wood; it works best because it's flexible...

...resulting in a tremendous amount of waste!

Lunchtime! The fumes don't seem to affect the appetite!

Meanwhile, the insulation waste continues to accumulate...

...will someone please invent a way of recycling this!

Walls and ceilings of the main part of the house are now completely insulated.


The low-density (1/2 lb) foam areas -- all the main floor walls and some of the ceilings -- having been sprayed, the contractor then switched his equipment to the high-density (2-lb) product, the BASF Walltite blue foam.

First, he filled the previously described six-inch open space around the perimeter of the sunroom-office floor, and now he's applying a few inches of blue foam on top of the rigid foam that we had installed earlier.

Now, the contractor is spraying the crawl space sill plates and walls with blue foam.

The fog is from the spraying: that's why the installer is wearing a respirator that is attached to a separate air supply equipment located outdoors.

Another advantage of the high-density foam
is the way it seals around objects.
This dryer duct has been encased,
eliminating any possible draft or leak.

Here we see the sunroom-office with two kinds of spray foam insulation in place.

Last, but not least, the kitchen-dinette ceiling also received
four inches of blue spray foam insulation.

High-density foam -- like this blue one -- is ideal for cathedral ceilings -- as it requires no ventilation.

It doesn't require vapor barriers either, but we used them anyway.

The dark side of my spray foam insulation project...

...and the light side!


If, after researching the subject, you decide that insulating your new home, -- or retrofitting your existing home -- with spray foam home insulation is the way to go, here’s what I learned from my own experience:

  1. Get as many estimates as you can, and make sure they all cover the same areas with the same R-values, so you can compare apples with apples.
  2. Get as much information and explanations from the home insulation contractors as you possibly can. In our case, for instance, we used a very good suggestion from one contractor to get a better result from another contractor. So, ask questions, point out possible problems, etc.
  3. If you’re retrofitting, gut the inside completely. Instead of demolishing everything, do as much deconstruction as you can.
  4. Prepare your surfaces carefully by removing all nails, especially if you’re going to be using low-density foam. Trimming off the excess with a saw requires that all studs be nail-free. The home insulation contractor will charge you less if he doesn’t have to do any preparation.
  5. Make sure that all the other trades (plumber, electrician), have got all their roughing-in done to the point where the pipes and wires that are in place can be completely buried in foam insulation.
  6. Go over everything once before “D-Day” with the home insulation contractor. You will then have time to have details rectified before it’s too late. Or to have that forgotten fixture put in.
  7. Vacuum everything. Even if the contractor tells you it’s not necessary to get rid of the dust, it just makes sense that if you want the foam to adhere properly and get into every cranny, the surfaces have to be clean.
  8. Make sure that the product name, the number of inches and the expected R-value are all specified and guaranteed in the contract.
  9. Get a respirator for yourself if you’re going to be around – and you should be. Check for missed spots, point them out to the installer and have him rectify them before you pay him.
  10. Get earplugs as well! The engines that are out in the truck, on the street, are extremely noisy.
  11. Warn the neighbors in advance, about the noise and how long it will last; they may want to stay away. (The contractor can tell you how long it will take.) Better yet, invite them in for a peek and rave about the money you'll be saving -- they may decide to insulate their house too!
  12. Sit back and enjoy your energy efficient home!

Other Insulation Types We Used


For interior walls, we went for a more economical product. The new stairwell wall, for instance, was done with 24-inch wide fiberglass batts. I would have preferred rock wool (it's greener), but it's not available locally.

The warm [room] side will get covered with vapor barrier and drywall, but the stairwell side, which is the cold side, will only get drywall.

Fiberglass batts on room side...

...and on stairwell side, with slat reinforcement which will serve as support for the drywall.

Unfortunately, we couldn't use the old fiberglass insulation that we had carefully taken out of the walls during the deconstruction phase, with the idea of reusing it, because that was only 16 inches wide and this new wall's studs are 24 inches apart.

However, we will be able to use it in the basement laundry room walls and if there's any left, in the attic.


Please see the earlier section, where we describe the way we used this material to build up the sunroom-office floor.


In the kitchen-dinette, we added foil insulation to the walls, on top of the spray foam. This unusual product doubles as a vapor barrier but it's a bit tricky to install, and I have given it its own page.

Click here for our page on foil insulation.

What About DIY Spray Foam Insulation?

Although most home insulation falls under the "do-it-yourself" category, I didn't consider spray foam to be one of them.

Spray foam is NOT a product for amateurs. Spray foam contractors working for responsible companies have received serious training from the product manufacturer.

If you decide to use one of those spray foam kits, be sure to follow the directions and take every possible precaution to avoid inhaling the fumes.

As you have seen above, special protection equipment is required, and that's because even if the product itself not toxic, the fumes are damaging to the lungs.

The small cans of spray foam insulation for filling gaps are okay, and we used a tremendous number of them. They come in two types: low-expansion for around doors and windows, and high-expansion for filling other types of gaps. Check the can label to be sure; using the wrong type around doors and windows can be fatal.



Foil Insulation | Attic Door Insulation | Water Heater Insulation



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United States


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United States


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A few years ago, I bought this fixer-upper for $10,000.

It had been vacant for six years, had no water supply, needed a new roof, and was likely to conceal an unsuspected number of nasty flaws.

Don't believe me? See these "Before" pictures.

My intention was to turn it into as "green" as home as I could, within my physical, financial, and geographical limits – and to share this adventure with you, step-by-step and dollar-by-dollar.

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