A safe insulation with good insulation properties

I was interested in Icynene insulation pros and cons some years ago when I did a home energy retrofit on my 1920 Toronto house. Throughout the ground floor I had only one and a half inches of air gap between my plaster and lathe walls and two courses of exterior brick, and what with cracks in the plaster, cracked or missing mortar on the bricks, and the complete lack of insulation, the ground floor was pretty chilly. But my home energy auditor recommended Icynene insulation for these walls, and I found a local insulation company that was able to add Icynene to the walls for a reasonable price.

They injected the Icynene into the walls by drilling two one inch diameter holes in each wall section (the space between two studs). They then sprayed Icynene into the lower hole first, and once they had filled the cavity up to that point, they plugged it with a cork that was pushed flush against the hole (actually, slightly recessed), and then filled the cavity the rest of the way through the second hole, which they also plugged. Then with a putty knife and some spackle, they covered over the holes, and left it to me to sand and repaint where they had applied the Icynene.

Within two days of the application I had repainted using a small roller brush (to recreate the roller texture of the wall paint) and you could hardly tell that anything had changed. And we noticed a big difference to the comfort of our ground floor. In fact, the main problem was that our second floor became much colder in winter because the ground floor, where the furnace thermostat was located, now held its heat better, so the second floor, which at that time was poorly insulated, got colder. (We solved this five years later by gutting the second floor and re-insulating with 6″ of Roxul!)

Let’s look at Icynene insulation pros and cons based on my experience and the research I did to determine whether this would be a good energy efficiency investment.

Benefits of Icynene insulation

Ease of installation: One of the first benefits of Icynene insulation is that it can be installed in an existing wall cavity with minimal disturbance to your home or to the wall surface. Just remove furniture from outside walls, and let the installers do their work. A little touch-up on your part a day or two later, and you’re done.

Cost: Most people will tell you that Icynene is significantly more expensive than other forms of insulation, but then that depends what you’re trying to accomplish. While Icynene insulation is not cheap, it is still a bargain compared to stripping down your walls to the brick and then putting in new studs, insulation, and drywall and repainting everything. I had Icynene insulation applied to my dining room, living room, front hall, and part of my basement stairwell, as well as to a floor cavity in a second floor room that overhangs the front porch, and the total cost (way back in 1998) was $1,700 Canadian; that’s about the same as $1,200 US at the time. If I had used foam board or fiberglass I would have spent probably $200-300 on the actual insulation, but would have spent countless hours gutting, had to pay to dispose of the demolition waste, and then have to pay for new vapor barrier, new drywall, new paint, and so on, not to mention those countless hours of extra work.

Insulation value: Icynene insulation has a modest R value of about 3.6 per inch, in the same ballpark as cellulose or fiberglass. You can get extruded foam insulation with R values between R-3.5 and R-6 per inch, but of course you can’t inject foam boards through a 1-inch hole! And for a larger wall cavity or when adding insulation to a wall that hasn’t yet been closed up, you don’t want to be cutting board after board of this foam insulation.

Draft protection: Don’t be fooled by the modest R value of Icyene insulation. The fact is that upgrading your insulation from R-13 to R-40 has only a modest impact on conductive heat losses – only about 5% – while about 40% of heat loss from a home is due to convection – air actually leaking between indoors and outdoors. Because Icynene forms a complete vapor barrier it completely stops these convection heat losses, so that a wall like mine with 1.5 inches of Icynene foam insulation – or R 5.4 – actually behaves more like R-13 or R-20 when you factor in the vapor barrier. Another benefit of Icynene insulation is that it can be applied as part of the insulation to a crawl space floor or flat roof (for example, we are getting Icynene injected into the ceiling of the flat roof we are building over a new kitchen addition) to provide both a complete vapor barrier and a starting level of insulation; the remainder of the cavity can be filled with mineral wool or fiberglass batts.

Simplified construction: Because Icynene acts as a vapor barrier, in some projects you can get away without installing a separate vapor barrier, which saves a little bit of time and money (not enough to make the total cost of a project with Icynene cheaper than a project with just traditional batt insulation, but this is a tradeoff of financial costs against non-financial benefits). In new projects, Icynene is sprayed against the wall cavity between studs (or the ceiling cavity between joists) and then a long two-handled blade is drawn down level with the edges of the studs to cut away the extra. Toss drywall on top of this, screw it, tape it, mud it and sand it, and you’re done. While this cutting process still preserves the vapor barrier due to the millions of sealed bubbles behind the cut area, note that some municipal building inspectors may consider this to have broken the vapor barrier, so check with your inspector before you do this. It is possible, especially in thicker wall cavities, for the installers to keep the application recessed from the studs enough that you preserve the surface of the foam without requiring it to be cut; this of course saves you the hassle of dealing with a misinformed inspector, though it means less insulation for you.

Insulate hard to get areas: One of the great pros of Icynene insulation is that it can be injected into areas that are hard to insulate otherwise. For example, if you are redoing your floors and have removed the existing flooring, you can ask your installer to inject it into the spaces between floor joists against the outside walls, as this is traditionally an area where cold can seep into older homes (resulting in warm walls and a cold floor after regular insulation is applied). In our case we were able to insulate the space above our front porch (beneath the front bedrooms) with two small holes drilled in each room through the oak flooring; this was far less intrusive than tearing off the floor or the porch ceiling to keep those bedroom floors from being frigid in winter.

Better structural integrity: Fiber insulation (fiberglass, cellulose, mineral wool etc.) does nothing to increase the structural integrity of your home. Foam insulation such as Icynene, on the other hand, acts as a very strong glue to help hold your home together. Plaster lathe or drywall is less likely to come loose from walls (for instance during the heaving that happens to most wood-framed houses on very windy days) if the cavities are injected with Icynene.

Better long-term insulation than fiber: When we gutted our second floor walls and insulated with batts of Roxul insulation, I discovered that the cellulose insulation that had been injected into the walls in the 1970’s had settled so that the top third of each section of wall cavity had no insulation in it at all. With Icynene insulation, assuming the installers properly fill each wall cavity, they should stay filled for decades to come; foam insulation doesn’t settle. And vermin have a harder time nesting in or chewing their way through Icynene than through fiber insulation.

Environmentally friendly: The newer LD-R-50 formulation of Icynene uses a much larger percentage of renewable, plant-derived oils, than the previous formulation based on Polyol, a petroleum product (both versions of Icynene are still available however). LD-R-50 exceeds the minimum renewable requirement for a bio-based material, which means it can help contribute towards a building getting points or credits under an assortment of green building standards, such as the LEED programs for homes, schools, and other types of buildings. Icynene is also free from HFC’s (hydro-fluoro-carbons – the replacement for ozone-damaging chloro-fluoro-carbons, better than CFCs but they still contribute to climate change). Finally, Icynene uses a water-based blowing system that is free from PBDE’s or polybrominated diphenyl esthers, a family of flame retardant chemicals used in some other foam insulations. PBDE’s have known or suspected health impacts including delayed mental and physical development in infants, and reduced fertility in adults.

Disadvantages of Icynene insulation

When considering Icynene insulation pros and cons it’s important to stress that overall, this insulation works very well and its environmental impact is chiefly positive, as it can help homeowners significantly cut back on their heating and cooling bills and therefore reduce their consumption of home heating fuels and their impact on climate change.

That being said, here are some of the cons of icynene insulation, including ones I observed when I had this insulation installed in my ground floor 13 years ago.

Bulging walls: If your installers aren’t extremely careful, there is a risk that they can overfill some of the stud cavities. Icynene foam insulation continues to expand for some time after it has been injected; normally the installers leave the two holes open when filling closed wall cavities, to give any excess foam time to escape; they can then wait until that foam dries, and cut off the protruding material before applying the cork and spackle to seal the holes. However, if they overfill and then seal the holes too early, the expanding foam insulation may not have anywhere to escape to, and so it exerts pressure on the wall itself and can cause the plaster or drywall to bulge. We saw this in our basement walls, where the installers were overzealous in the amount of Icynene insulation they used: those walls now bulge out in places so much that the basement stairwell banister, which has about two inches of clearance from the wall at the top, has only a half inch of clearance partway down – in other words, the wall bulges out by one and a half inches!

Messy cleanup: Like most liquid-injected insulating foams, when Icynene cures it forms a hard bubbly foam that can be quite challenging to remove. If the installers are careful they wipe away any Icynene that sticks out through wall holes, but even the thin film left behind aquires a glossy yellow surface that can only be removed by sanding it down several days later; painting over the glossy surface changes its color but doesn’t hide it. It can also leak out around the molding or trim for doors, windows, baseboards or quarterround, as it did in several places on our ground floor. When it gets on varnished hardwood trim you can’t just sand it off without damaging the finish, so be prepared for some hard work sanding, re-staining, and re-varnishing any hardwood trim that gets Icynene on it.

Not ideal for large cavities: I wouldn’t necessarily recommend using Icynene foam insulation in a thicker wall cavity. In fact my installer initially recommended switching to blown fiberglass when I told him I had two-inch wall cavities; he suggested Icynene was better suited to one inch or less. I’ve had several contractors suggest that you can use Icynene insulation in any thickness wall, but I believe you will find the price prohibitive for filling really thick wall cavities. Again, using a thin layer of Icyene applied to the wall cavity of an unfinished wall, and then adding batt insulation on top of that, may be a good compromise that gets you the superior vapor barrier and convection control of Icynene with the affordability of batt insulation.

Not a DIY project: Forget about applying Icynene insulation yourself as a DIY job. You have to hire professionals to install Icynene foam insulation. This is part of the cost equation: it’s much more expensive to pay an insulation company to apply Icynene, than it is to drive off to the building center yourself, buy batt installation, and install that yourself.

1 reply
  1. Wayne Cowan
    Wayne Cowan says:

    Hello: We have just bought an old ranch house in Wyoming. It is made of concrete and is 103 years old. It has No insulation anywhere except some fiberglass insulation in the attic. I am contemplating building stud walls on the inside of exterior walls and having these stub bays sprayed with Icynene foam. We then will cover the walls with ship lap some other material. We are not sheet rock fans. We are also thinking about spraying the underside of the roof as well.

    Any suggestions?

    Thank you



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