Insulating Beneath a Bay Window Floor

There's sometimes a fine line between insulating and renovation. Today's task was equal measures of both. The north side of the house features a bay window in the dining room, a humble adornment that breaks up the monotonous lines of a four-square house design. The bay window adds about 36 square feet of floor area with no conditioned space beneath it:


This infrared image, taken from the interior during our March 2009 energy audit, clearly shows heat loss experienced in this area. The cold area, where the floor intersects the baseboard, is in blue. Note also the heat signature of the air behind these fairly sheer curtains!


An exterior shot shows the 1"x5", tongue-in-groove planking that clad the underside of the 2"x9" floor joists:


I knew that 30 plus years ago, some fiberglass insulation batts had been stuffed into joist cavities from the inside. But as I suspected, there was no attempt to air seal those cavities, certainly because of limited access. So with hard-hat, dust mask, and crowbar, I yanked off the 1"x5" external cladding, yielding full access to the joist cavity for the first time in 94 years. The insulation batts were poorly-fitted. They were also soot-stained, which is perfect evidence of air infiltration/exfiltration-- an action which effectively renders the insulation useless. But now at least, the joist bays were fully exposed. The gaps over the sill are wide open, leading straight into the basement utility room:


My insulation solution involved 2"-thick polyisocyanurate foam boards rated at R-12. These were cut for friction-fit, then sealed with expandable foam. Horizontal slabs (about 32"x16") were applied directly to the underside of the floor. Smaller slabs (7"x16") were placed vertically in the bays, directly over the sills. Per the insulation manufacturer's instructions, the reflective foil side faces the exterior:


I'm not done yet. The bays really should use a second layer of insulation boards, giving me a total of 4" thickness and a cumulative R24 insulation value. However, I ran out of time today. For now, there's some 1/2-inch, B-grade, water-sealed plywood screwed into place. After the area is fully insulated, I will re-clad the under-surface with a no-frills trim that is suitable for this little-used utility room entrance.

This image also reveals the archeology of siding applied to this house over the years. The outermost layer is aluminum siding, which I'll guess was applied in the 1970s. The aluminum siding came with its own sub-surface of expanded-cell polystrene panels-- the same stuff that's used for styofoam cups. Beneath that is a layer of asbestos (!) shingles. Then comes the original finish layer of cedar shingles. There were applied directly to the structural cladding of 1"x6" planks fitted horizontally across the studs. As you may know, that was THE way to construct wooden-frame houses before plywood with waterproof adhesive became available in the 1930s:


This task led to the discovery of some unexpected treasures. A previous owner, probably during the Great Depression of the 1930s, used these joist bays to hide away Christmas presents for the kids. The frugal homeowner apparently reused boxes from year to year. Over time, some were forgotten. These empty boxes, tokens of old-house charm, fell out when I removed the bay window's old under-surface cladding:


If you're curious, the card reads "To Helen, from Uncle Elmer and Josie."

[Update, August 3, 2009] Now it's done. A mildew-resistant latex paint was applied to the new plywood cladding:

Insulating the Crawlspace: My Wonderful, Do-It-Yourself Experience

I spent the better part of my weekend addressing the energy integrity of the crawl space under my kitchen. The issue here is a cold kitchen floor during the winter, along with some mighty drafts. What ensues is a story of air sealing and insulating. It's a story completely devoid of glamour. Here's the recap.

The deck on the rear of our house has no more than three feet of clearance from the ground. So you pull out the trellis and crawl under the deck... around the corner... and voila! Here's the trap door to the crawl space:


What a charming space! It's 6x20 feet, with head clearance of about 40 inches. The floor is concrete. It's home to countless rhaphidophoridae, better known in these parts as "cave crickets." Aside from the fact that they jump AT you when you swat them, they are harmless and no more than a nuisance. Cave crickets love the voids between masonry foundations and rim joists. Of these, I have many:


The crawl space was insulated sometime before we bought the house (1998). Unfortunately, the previous job was ineffective: batts of R-11 fiberglass were installed (nominally) between the floor joists with its foil backing facing down, or in other words, away from the underside of the floor above. By this time, any batts that had not already fallen were sagging and ABOUT to fall anyway. So task number one was to pull out all the old insulation.

My strategy called for the installation of 2" thick rigid foam board insulation rated at R-12:


But before I could do that, I had to remove superfluous 3/4-inch wood planking that was attached to the underside of the joists, covering about half the area in total. I'm not sure what this "sandwiching" of the 8" floor joists accomplished. The lower layer had been busted through in places over the years to accommodate electrical and plumbing work. It was anything but air tight. I removed most of the under layer-- enough to allow me to slip sheets of the rigid board insulation in place, flush against the underside of the kitchen floor. Doing so was tricky, since since there were pipes and struts to work around.

This is what the space looked like after clearing out the old insulation, and air sealing the gaps along the rim joist and where walls intersected with the underside of the floor:


Some of the voids in the rim joist were huge, ostensibly for the purpose of running electrical wires and pipes of various description. The previous owner (or some contractor?) loosely plugged these voids with fiberglass insulation. This stuff was soot-stained-- evidence of air penetration and the general ineffectiveness of this approach. This old insulation was removed, the voids were planked over, and the seams were air sealed with a bead of expandable foam:


So now the insulation boards are in place, fit snug against the underside of the floor. They are sealed in place with the expandable foam which works wonderfully as glue. It's hard to see the insulation boards in the picture because they have a shiny metallic surface. This is the best I could do:


Nothing about this was pretty, but the last photo here captures several elements:


The rigid insulation boards are foil backed-- a bit difficult to see here, but it's cut to fit between the joists. You can also see batts of R-19 fiberglass wrapped in plastic bags and fit snuggly (not compressed) in perimeter spaces. The plastic bags prevent air filtration through the batts. This also shows a 1/2-inch water line that has been wrapped in self-sealing polymer foam pipe insulation. That latter item is a precaution: we've never had the pipes freeze, probably because the pipes have enjoyed heat that radiates downward from the kitchen. But the new insulation puts an end to all that: the pipes will be at risk this winter in a presumably colder crawl space. The "whipped cream" is just the expandable foam, which may be too generously applied to seams and voids. I have gone through a couple dozen cans of the stuff (counting the attic work) and still haven't mastered the flow. It sure is handy, though.

Air Sealing the Attic Knee-Wall Area

The latest episode of my adventure involved improving the insulation of the attic. Once upon a time, I converted this from unfinished to finished space, using knee walls to maximize the occupied space under the hipped roof (the roof slopes at about 45 degrees on all four sides-- a characteristic of four-square house design). At the time, I was not motivated to research proper insulation techniques for attics. I've come to regret that, because in finishing the space the way I did, I lost a number of opportunities to make the house more energy efficient than what it could be. Nevertheless, the cause is not totally lost-- I am making a number of improvements behind the kneewall, in the areas where the sloping roof intersects with the soffit and the top sills of the walls.

Ten years ago, I attached batts of fiberglass insulation backed with kraft paper to the rafters (the sloped beams supporting the roof sheathing). The batts were then faced with drywall:

As you can see, this left a gap at the bottom in the bays between the floor joists. During the winter, heated air simply flowed through these passages as it pleased. One consequence of that is the formation of ice dams and some pretty mean ice cycles whenever we get an appreciable snowfall. The medicine for this is to fill these soffit gaps with insulation wrapped in a vapor barrier that prevents air from passing through it. This was achieved in several steps. First, I pulled back the existing insulation from the rafters and attached baffles to the underside of the roof sheathing. Baffles protect the roof's under-surface from warm air, which would lead ultimately to ice dams and a host of subsequent problems:

The second step involved sealing the top plate of walls with the foam-in-a-can product. This prevents air from escaping into the attic from heated spaces below:

Next, I manufactured a number of insulation "bricks," in this case, using unfaced R-19 fiberglass batts. The batts are sold in 24" by 48" sheets. My rafters and ceiling joists are spaced 24 inches on-center. So I cut the batts into thirds and and quarters, and wrapped them snuggly (but not compressed) in 13-gallon plastic bags, which have a 24" dimension along their bottom edge:

These bricks (or "pillows," if you prefer) are then tucked into the rafter bays:

This was also a good opportunity to fill voids in the interior walls, which are also an escape route for heated air. I'm pointing to such a void here:

This particular gap was filled with styrofoam from a packing crate:

This was then topped of with the foam-in-a-can stuff (applied after this photo was taken). By the way, those latex gloves? Absolutely worthless; they rip with little or no provocation.

It took me about four hours to complete about twenty linear-feet of rafter bays. Once again, I emerged absolutely filthy from the confines behind the kneewall-- an area that only a contortionist would love. But once again, the pay-off is the immense satisfaction of knowing that this task has been completed. I have two more sessions of this before the entire attic perimeter is finished. Then my attention turns to the floor joists in the basement. Truth be told, I can't wait.

Stopping Air Leakage Through the Dryer Vent

In an earlier post, I introduced the issue of air leakage around dryer vents. So, I went from this:

To this:
I screwed it onto the base of the old vent and caulked around the interface. Like everything these days, it's made of plastic. So I painted it to match the house, and hopefully, to protect it from the sun's ultraviolet rays which will eventually breakdown may kinds of plastic. We'll see. In the meantime, the basic idea of this contraption is to prevent conditioned air from escaping the house. It works very much like an inverted-bucket steam strap , for those of you who are familiar with steam boiler systems. The lid comes off so you can clean the interior. Here's what is looks like with the dryer off:

...and with the dryer on:

As an operating issue, the device "sweats," because after all, it's expelling moist, humid air from the dryer. So it naturally wants to grow "fur" from dryer lint. Periodic cleaning will be necessary. Fortunately, the lid snaps on and off easily, and the bucket slips right out. It's a goofy-looking contraption, somehow reminiscent of a locomotive whistle, but hey, if it saves some energy, I'm all for it.

The Refrigerator Coil Lesson

You probably know that your refrigerator is the single largest electricity-consuming appliance in your household (unless you have a heat pump or a huge air conditioning load). So it makes sense to install a high-efficiency unit. A current "Energy Star" qualified fridge uses 40 percent less electricity than a model sold in 2001.

Refrigerators are a fairly low-maintenance appliance. The key to maintaining its performance is to clean the condenser coils. These are located on the rear or underneath the unit.

So like good little doobies, we sought out an Energy Star Sears Kenmore fridge when we remodelled the kitchen in 2003. Take a look at this picture, and you'll see where I'm going with this. You're looking at the underside of our refrigerator from the front. The grill has been removed, revealing the condenser coils that are arranged in several parallel banks:



All the literature, including the manual that came with this particular unit, tells you to periodically clean the coils. Air being drawn back to the fan passes through the coil fins, which have maybe a one-eighth inch space between them. But lo and behold: the coils are configured SIDEWAYS. You can clean the face of the first bank, but that first bank prevents you from reaching the inner banks. There is no grill for side access, and the coil banks don't pull out. A brush made especially for this purpose is of no use with this configuration.

I called Sears and went through the usual automated response system. I finally found a tech support guy who admitted that this particular model's coil configuration was a "design flaw." He had several suggestions:

(1) Use a high-powered shop vac. Sorry, but that's not strong enough to pull up layers of dust that have been cemented in place by five years worth of humidity.

(2) Call Sears Service, who will send out a guy in a cargo van sometime in the next week who will repeat my shop vac experience, but charge me a couple hundred dollars for it. I'll pass.

(3) Lay the fridge on its back, remove the bottom plate, and get access to the coils that way. This probably is the best "medicine," but I'm figuring that the cure is worse than the disease. By the way, placing a refrigerator on its back or side (even if you have the space and strength to do it) is usually traumatic for the refrigerant system.

Let our experience be your guide. It's fine and dandy to shop for an appliance that is the right size, color, and has the right features, etc. I was aware of coil maintenance five years ago when shopping for a fridge, but took for granted that there would be no issues with access.

Refrigerator coils maintenance makes sense as a do-it-yourself activity, assuming you have access to the coils. It's not worth paying someone to do. Consequently, I wonder how many households bother to do this? I'm thinking about my mother-in-law, who maintains TWO refrigerators-- one pre-dating 2001 and the other pre-dating 1994. I promise you the coils have NEVER been cleaned on either one.

Degrees of Heat and Consumption

Let no one, least of all me, be surprised by the relationship between average monthly temperature and a domestic household's monthly therm (natural gas) consumption. Thanks to archived utility bill data, I can plot the January-December gas consumption onward from January 2005:


Two things jump out at me in this picture. First, before 2006, I was not in the habit of turning off the power supply to the boiler each May 1. It ran on standby all summer long. Hence, with the boiler running in 2005, my total natural gas consumption during the summer months was effectively DOUBLE what it should have been for that period. The second point is the normal summer months give me an idea of how much gas is devoted to water heating and cooking combined, since those are the only other gas appliances in use.

The take-away here is that the year-on-year data trends are a way of detecting anomalies in consumption. Note however that this is not "real time" error detection; in effect, such information becomes evident when you get your utility bill, usually a couple weeks after the meter reading date. It's better than nothing, but certainly not as useful as having sub-meters for each appliance. And while electricity submetering is fairly easy to do for domestic appliances, even I am not inclined to pursue that... not yet, at least.

Air Infiltration Around the Dryer Vent

Now I need to decide what to do around the dryer vent. Our dryer is immediately off the kitchen. It's right next to an exterior wall, so the vent has a very short run. However, this configuration allows a LOT of air leakage:


One option is to seal around the orifice with the appropriate insulating material. But what? The foam-in-a-can stuff is combustible above 240 degrees fahrenheit; I'm reading that the high setting on a clothes dryer approaches 350 degrees. Another option involves this contraption:

I know very little about it, other than its supporting webpage.

The blogger at Dover Projects provided a thoughtful post on the same subject. A similar discussion is on Green Talk.

[Post script: I eventually installed one of these; the story is here.]