On insulation, again

28 Feb 2007

Got questions about the environment? Ask Umbra.

Dear Umbra,

You're wrong, you can blow in insulation yourself. At every Home Depot I've been to, you can buy either fiberglass loose-fill insulation or cellulose loose-fill insulation, and you can also rent the machine that you use to blow it into the attic. Sometimes, if you purchase enough insulation, you can rent the machine gratis.

John David
Brunswick, Maine

Ask Umbra continues below

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Dearest John,

Excellent. What a great new piece of information for readers led slightly astray by my previous column. Let's append a few addenda to my insulation piece and encourage everyone to consider blowing in their own insulation.

Don't be afraid to DIY.

Photo: iStockphoto

Note a comment below the original insulation column where an enterprising reader enthusiastically describes a successful experience blowing recycled paper into an attic. Now why would you do this instead of laying down "bats" (the familiar rolled-up blankets)?

Well, here is an interesting evaluation of blow-in cellulose with some comparisons to fiberglass bats, and fairly detailed instructions on how blowing in will work. Apparently blown insulation is better at filling little nooks and crannies, whereas with bats it's easy to leave drafty gaps. Blown insulation can also be added atop existing bat insulation to bring an attic (for example) up to the proper R-value (see last column for revelation that R-value is the measurement of resistance to heat exchange).

A do-it-yourself project can be daunting, what with the equipment rental and the scurrying about in an attic, but it is enticing for cost and self-image reasons. Seems the right way to start is to read up thoroughly, talk to professionals when buying materials and renting equipment, and proceed carefully. Without (needless to say) having tried it myself, I appreciated these instructions and suggestions for calculating real R-values, and the frequent mistakes listed at this do-it-yourself website. I get the sense that blowing into exterior walls could also be attempted by the truly persevering, were they willing to get thoroughly educated on the techniques.

I am, however, putting the cart before the horse. Another reader, Mike in Maryland, wrote in to say that insulating means nothing without sealing the attic bypasses. Attic bypasses are areas where heating or cooled ("conditioned") parts of the house are open to the attic, and according to the literature they are plentiful. In each area of the conditioned house that is in contact with the attic, there may be a bypass. For example, there is probably a gap around the chimney, or around recessed lighting fixtures, or any venting pipes, or the attic access door. Heat from the living area will rise and escape into the attic through these openings unless they are sealed, undercutting any insulative efforts that have been made. It is possible to seal the bypasses yourself, but please follow all directions (here's Mike's suggested PDF) and be very careful to use recommended materials, because there are potential hazards of moisture and fire if the job is not done correctly.

Frankly, I like to imagine myself as a DIYer -- and I want to vigorously support all DIYing -- but after reading all the instructions I felt a little tired. Which leads to my last piece of advice for the inexperienced: be sure you have correctly evaluated your capacity for attention to detail with this type of project. The above-mentioned fire hazards could be a serious downer.

Correctively,
Umbra

Yours is to wonder why, hers is to answer (or try). Please send Umbra any nagging question pertaining to the environment -- but first check out her FAQs!

The claims made in this column may not reflect the views of this magazine. Neither the magazine nor the author guarantees that any advice contained in this column is wise or safe. Please use this column at your own risk.

Umbra Fisk is Grist Research Associate II, Hardcover and Periodicals Unit, floors 2B-4B.

Comments: (5 comments)

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Do it yourself insulation

As a builder, this is one area I leave to the pro's, blowing your own insulation is like hanging your own garage door. Yes you can do it yourself but skilled trades people will do the same work in a fraction of the time. The insulation companies buy insulation in large quantities for a lower price than the home handy person will buy it for at the home improvement chains, if you have to rent the blower to boot, there is little money to be saved. A note about professional blown insulation, ask for a certificate (builders statement) for the finished insulation, stating the R-value, type of insulation and thickness, and number of bags used. One positive aspect of blown fiberglass is the light weight so high R-values can be achieved without fear of overloading the ceiling drywall.

by LeadByExample at 5:14 PM on 28 Feb 2007

Excellent discussion ...

Thanks ...

Now, as for "attic bypasses" -- many split levels (such as mine) and other homes were built with interior walls directly open into the attic. These create "chimney" effects, leaving the walls hotter in summer and colder in winter. Sealing up some of these gaps led to wall warming by over five degrees within an hour for many walls.

As for blowing insulation ... if it is cellulose, I disagree with LeadByExample. This is a great 'neighbors' project. Find a neighbor/friend who wants to insulate. He/she helps you in your home with some air gap sealing on one day and the next day you blow in the insulation together. The next outing, up into their attic you go to seal gaps and work the insulation together. As long as the beers are cold at the end of the job, it isn't so bad.

Blogging regularly at Get Energy Smart. NOW!!! to Energize America .

by A Siegel at 8:53 PM on 28 Feb 2007

How To Reduce Your Heating Bills This Winter

Here is a related article:

How To Reduce Your Heating Bills This Winter

Imagine leaving a window open all winter long -- the heat loss, cold drafts and wasted energy! If your home has a folding attic stair, a whole house fan or AC Return, a fireplace or a clothes dryer, that may be just what is occurring in your home every day.

These often overlooked sources of heat loss and air leakage can cause heat to pour out and the cold outside air to rush in -- costing you higher heating bills.

Air leaks are the largest source of heating and cooling loss in the home. Air leaks occur through the small cracks around doors, windows, pipes, etc. Most homeowners are well aware of the benefits caulk and weatherstripping provide to minimize heat loss and cold drafts.

But what can you do about the four largest "holes" in your home -- the folding attic stair, the whole house fan or AC return, the fireplace, and the clothes dryer? Here are some tips and techniques that can easily, quickly and inexpensively seal and insulate these holes.

Attic Stairs

When attic stairs are installed, a large hole (approximately 10 square feet) is created in your ceiling. The ceiling and insulation that were there have to be removed, leaving only a thin, unsealed, sheet of plywood.

Your attic space is ventilated directly to the outdoors. In the winter, the attic space can be very cold, and in the summer it can be very hot. And what is separating your conditioned house from your unconditioned attic? That thin sheet of plywood.

Often a gap can be observed around the perimeter of the door. Try this yourself: at night, turn on the attic light and shut the attic stairway door -- do you see any light coming through? These are gaps add up to a large opening where your heated/cooled air leaks out 24 hours a day. This is like leaving a window open all year round.

An easy, low-cost solution to this problem is to add an attic stair cover. An attic stair cover provides an air seal, reducing the air leaks. Add the desired amount of insulation over the cover to restore the insulation removed from the ceiling.

Whole House Fans and AC Returns

Much like attic stairs above, when whole house fans are installed, a large hole (up to 16 square feet or larger) is created in your ceiling. The ceiling and insulation that were there have to be removed, leaving only leaky ceiling shutter between the house and the outdoors.

An easy, low-cost solution to this problem is to add a whole house fan cover. Installed from the attic side, the whole house fan cover is invisible. Cover the fan to reduce heating and air-conditioning loss, remove it when use of the fan is desired.

If attic access is inconvenient, or for AC returns, a ceiling shutter cover is another option for reducing heat loss through the ceiling shutter and AC return. Made from R-8, textured, thin, white flexible insulation, and installed from the house side over the ceiling shutter with Velcro, a whole house fan shutter cover is easily installed and removed.

Fireplaces

Sixty-five percent, or approximately 100 million homes, in North America are constructed with wood or gas burning fireplaces. Unfortunately there are negative side effects that the fireplace brings to a home especially during the winter home-heating season. Fireplaces are energy losers.

Researchers have studied this to determine the amount of heat loss through a fireplace, and the results are amazing. One research study showed that an open damper on an unused fireplace in a well-insulated house can raise overall heating-energy consumption by 30 percent.

A recent study showed that for many consumers, their heating bills may be more than $500 higher per winter due to the air leakage and wasted energy caused by fireplaces.

Why does a home with a fireplace have higher heating bills? Hot air rises. Your heated air leaks out any exit it can find, and when warm heated air is drawn out of your home, cold outside air is drawn in to make up for it. The fireplace is like a giant straw sucking the heated air from your house.

An easy, low-cost solution to this problem is to add a fireplace draftstopper. Available from Battic Door, a company known for their energy conservation products, a fireplace draftstopper is an inflatable pillow that seals the damper, eliminating any air leaks. The pillow is removed whenever the fireplace is used, then reinserted after.

Clothes Dryer Exhaust Ducts

In many homes, the room with the clothes dryer is the coldest room in the house. Your clothes dryer is connected to an exhaust duct that is open to the outdoors. In the winter, cold air leaks in through the duct, through your dryer and into your house.

Dryer vents use a sheet-metal flapper to try to reduce this air leakage. This is very primitive technology that does not provide a positive seal to stop the air leakage. Compounding the problem is that over time, lint clogs the flapper valve causing it to stay open.

An easy, low-cost solution to this problem is to add a dryer vent seal. This will reduce unwanted air infiltration, and keep out pests, bees and rodents as well. The vent will remain closed unless the dryer is in use. When the dryer is in use, a floating shuttle rises to allow warm air, lint and moisture to escape.

If your home has a folding attic stair, a whole house fan, an AC return, a fireplace, and/or a clothes dryer, you can easily, quickly and inexpensively seal and insulate these holes. At Battic Door Energy Conservation Products, we have developed solutions to these and other energy-conservation related issues.

For more information on Battic Door's energy conservation solutions and products, visit www.batticdoor.com or send a S.A.S.E. to P.O. Box 15, Mansfield, MA 02048.

Mark D. Tyrol is a Professional Engineer specializing in cause and origin of construction defects. He developed several residential energy conservation products including an attic stair cover and a fireplace draftstopper. To learn more visit www.batticdoor.com

by batticdoor at 2:49 AM on 01 Mar 2007

insulation quality control

The only way you can really know how effective your insulation work was (whether it's a D-I-Y project or a professional installation) is to have your house tested with a blower door and an infrared camera afterwards.

The blower door tests for air leaks (responsible for almost half of a typical older home's thermal losses); the infrared camera tests for insulation voids--i.e., places the cellulose did not reach.

I've been participating in quality-control tests of recent insulation jobs in my community, and the results have been depressing. Five out of six houses we test, on average, have some serious deficiencies in their insulation work.

Professional insulation crews, simply put, have no idea how good a job they're doing--and it's all because they do not do the quality control testing afterwards. To repeat: You can have no idea whether you have a good insulation job if you do not hire an auditor WITH A BLOWER DOOR AND AN INFRARED CAMERA to test the job afterwards. Your utility can help you set this up, and may even have a program to subsidize it. Market rate for such audits can be about $400 (not cheap, but nonetheless a worthwhile investment in most cases); utility subsidies, when available, can cut this cost in half or more.

If professional crews have no idea how good a job they're doing, imagine the position of a do-it-yourselfer. Go ahead and do it yourself, but be doubly sure to get an audit--with the right equipment--afterwards. Then make sure you or your insulation company fixes any problems that show up during the audit.

by eldrenkamp at 5:43 AM on 01 Mar 2007

Performance testing

eldrenkamp makes some good points about quality verification. Blowing insulation in existing walls and getting all the voids is tricky, if this is being done during the heating season, an infrared camera can be used during the insulating process to make sure all spaces are filled. For an infrared camera to work there has to be a temperature differential between the conditioned space and the outdoor temperature, can also be done in summer when the home is air conditioned. Another trick is during the initial blower door test (before weatherization) infrared scan all thermal boundries (building envelope surfaces) and document this for the energy retrofit company to identify exactly the air leakage points and poorly insulated areas. Yet one more method for identifying air leaks is to reverse the blower door, pressurize the house, and use theatrical fog to pinpoint air leakage areas.

by LeadByExample at 7:03 AM on 01 Mar 2007

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Blowing It