This article was originally published in the January/February 1996 issue of Home Energy Magazine. Some formatting inconsistencies may be evident in older archive content.


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Home Energy Magazine Online January/February 1996


Having left their retrofit work overnight, these workers were astonished to find that freak winds had peeled the roof off of a mobile home in their absence!

Retrofits We'd Rather Forget

by Nancy Hurrelbrinck

Nancy Hurrelbrinck is Home Energy's assistant editor.

Insulation experts tell all, 
offering valuable lessons to the rest of us.

We all make mistakes. And the best of us make some of the biggest and best ones. An energy service company in New York installed light sensitive thermostats in a complex where the residents covered windows with heavy curtains to curtail air leakage. A crew in Chicago forgot to place a top plate in the top floor bathroom of a multifamily building; when they blew insulation into the roof, it filled the bathroom. A state official in the Midwest was inspecting the attic insulation in an FHA house when his foot slipped off the walk board and went through the ceiling drywall. And weatherization experts in Pittsburgh have discovered that a blower door can fill a house with decades' worth of accumulated soot.

These mishaps could visit anyone. Much as those visited would rather bury them, we think they deserve an airing on the pages of Home Energy. In this issue, we present some cautionary tales from the elites of insulation.

The Insulation Installation That Wouldn't End. 1) Installers started by nailing in Tyvek wrap to hold the blown-in insulation under a mobile home. 2) Later in the day, when the installers returned from lunch, the Tyvek had sagged to the point that it was sitting on the ground. 3) Hoping to solve the problem once and for all, the installers brought in chicken wire to support the saggy bag of insulation. They were foiled again, however, when they discovered within a week that the insulation had become soggy and useless.
When Weatherization Meets Weather Bruce Manclark of Delta-T, in Eugene, Oregon, and John Krigger of Saturn Resource Management, in Helena, Montana, were offering training in weatherization techniques, insulating underneath the roof of a mobile home. They unscrewed the roof on one side and lifted the edge to access the ceiling cavity with a blowing tube. When they left for the day, they didn't bother to screw down the ten feet of J-Rail (the strip that attaches the roof to the wall), because they knew they'd be back in the morning. That night, 60 mph winds came up and lifted the unfastened side of the roof. The occupants called 911, not understanding that the banging sound they heard was caused by a 60 ft x 14 ft piece of sheet metal flapping against their house.

Expect the worst from the weather gods. Batten down all hatches before leaving a job.


While Krigger's and Manclark's experience resulted from circumstances exceeding any reasonable person's expectations, some retrofit goofs stem more from a shortage of common sense. Andy Padian of the New York City Weatherization Coalition tells how his brother's house had three 4 ft x 4 ft bypasses in the attic. When the utility company sent a crew out to insulate the attic, they put fiberglass around the edge of each bypass and taped it, so they would not blow the cellulose into them. But they didn't seal the bypasses. Andy's brother's heating bills actually rose after the job was completed. The company also blew cellulose over the knob-and-tube wiring, creating a fire hazard.

Seal bypasses before insulating. Examine potential electrical hazards.


Fireside Tales Although cellulose is treated to resist fire (see Cellulose Insulation: Not Like Paper and Fire, HE Jan/Feb '91, p. 29), weatherizers still need to keep any insulation off of heat sources.

Once when Rob deKieffer of Sunpower, in Wheat Ridge, Colorado, was blowing cellulose insulation into the corners of a low-pitched roof, he didn't notice a recessed downlight in the bathroom ceiling. (Walking through the house and counting recessed fixtures is the best way to avoid such surprises in the attic.) The insulation reached the light and ignited, setting the roof on fire. Fire fighters had to rip the entire roof off.


Check carefully for heat sources before you blow in insulation.


A member of a volunteer insulation team in Pittsburgh had looked very carefully for existing heat sources, but she didn't realize that she'd brought one with her. She was lying in the cap of an attic, blowing cellulose. Her trouble light was on the floor next to her, and it was momentarily buried in cellulose a few times. Though she did remember to turn off the light when she left the job, it had generated enough heat to cause a fire.

One of the crew working downstairs saw smoke and thought it was cellulose dust, but when she went up to check, she found a fire. The fire department arrived and chopped a 4-ft hole in the ceiling, giving the insulation team a little more work. As the team repaired the hole the next day, they had a blower door running at low speed to keep the smoke smell out of the house. The blower door did its job so well that, when the fire chief came to inspect the house, he was amazed by the complete absence of smoke damage.

Several factors may have contributed to the fire. The old fiberglass insulation had flammable kraft facing. Cellulose had been blown in years before and may not have been fire rated. A blower door was being used to pressurize the house to keep out the cellulose dust, and it created air flow through the attic. The trouble light's broken 75W bulb had been replaced with a 100W bulb, making it create even more heat than usual (she now uses a fluorescent light). And the roof was only two feet from the floor at the highest point, reflecting heat back into the tight space.


Use a fluorescent trouble light and keep it away from the insulation.


Cellulose is fire-resistant, so it rarely causes fires and sometimes even serves to dampen them. Ben Brogoitti of Sun Power recalls how dense-pack cellulose installed in the flat roof of a ranch house actually extinguished a fire caused by faulty wiring.

Tom Wilson of Residential Energy Services in Fairchild, Wisconsin, has a similar story. When he and his crew at Northwest New Jersey Community Action Program first started using cellulose insulation back in the mid-1970s, they had been taught to use the dense pack sidewall method. They were called in to insulate a small fire-damaged cottage. The fire had started with a wood stove in the basement and had rapidly consumed most of the gable end sidewall above it.

Wilson and his crew packed the newly rebuilt wall as well as the undamaged walls with cellulose. Several months after they'd finished the job, the house had another basement fire, starting this time with the furnace beneath the opposite gable end wall. The second fire burned the floor above the furnace and scorched the wall studs, but it did not travel up the wall, thanks to the dampening effect of the cellulose insulation.

That was 20 years ago. Wilson says that he has become much more aware of health and safety issues since then. If he were to go into the same house now, he would make sure that the contractor rebuilding the wall installed fire-resistant material above the furnace's flue stack, since the flue was too close to the floor joists above it.


Keep an eye out for potential safety problems, even when they concern parts of the house you're not treating.


Bright Ideas
with Dim Vision Eddy Haber of the Illinois Department of Commerce and Community Affairs and Paul Knight of Domus Plus, in Chicago, were testing techniques to insulate floors in mobile homes when Haber had a great idea. Why not attach a sheet of Tyvek to the bottom of the mobile and fill it with cellulose? So they secured the Tyvek to the trailer with 1 x 2s, blew in the insulation, and left the site to eat lunch. When they returned, the belly of the mobile home was sagging to the ground. So they got some chicken wire and placed it under the Tyvek to pull it up against the mobile home's undercarriage. A week later, they got a call: the insulation was wet, because it had absorbed moisture through the Tyvek. (Tyvek blocks air while allowing water vapor to pass, but it will trap water in its liquid form. It is designed for vertical, nonload-bearing use as an air barrier.)


Consider all principles of building science and product design before implementing new ideas.


This moral also applies to routine jobs, as the following story attests. A weatherization training organization was demonstrating a new technique for insulating mobile home sidewalls. When they were removing the exterior wall panels from the home, someone asked whether the crew shouldn't number them. The trainer said, Naw. After they'd installed the insulation, they spent four hours trying to determine where the various wall panels went.

Whether our mistakes result from a bizarre chain of circumstances or lapses in forethought, there are always things we can do to lessen their likelihood. One of the best ways is to educate each other by sharing our horror stories. We owe our thanks to the weatherization experts who were brave enough to tell their tales here.


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