Cellulose Installed in Walls

March 2009

Many houses in Takoma Park are "Baloon Framed" - This means that the walls are hollow and the cavity goes all the way from the basement to the attic with no interruptions - in the winter, this allows heat from the house to pass through the walls and flow upward like in a chimney to the attic where it can leave the conditioned part of the house. Baloon Framed house with no insulation

However, there is hope! In this house, were were able to pry off two rows of wooden siding on the sides of the house to expose the old style board sheathing underneath. Siding being pried off the house

Holes were then drilled into the sheathing, one hole for each stud cavity inside the wall. holes drilled to allow cellulose injection

A flexible hose is inserted into each hole in turn, and the hose is connected to a powerful cellulose blowing machine sitting in a nearby truck. Cellulose insulation hose inserted in holes

The blower is turned on and cellulose flows into the wall. The pressure from the machine dense packs the cellulose (see sidebar). After each cavity is filled, the hole is plugged, and the hose is inserted into the next hole. Cellulose insulation injected into walls When the cellulose is installed, the siding is reinstalled (reusing the same boards), caulked, and spot painted. When done, you would never know that the job had been done, except that the homeowners are warmer, happier with lower heating bills, and enjoying a quieter house.Diagram of house

Dense Packed Cellulose

  • Cellulose is a green insulation made from ground up paper products
  • Dense Packing of Cellulose puts 3.5 pounds of cellulose into each cubic foot of wall.
  • Dense Packed Cellulose will settle in a wall cavity minimally compared to loose cellulose.
  • Dense Packing Cellulose has an insulation R value of 3.2 per inch, or R-13 inside a baloon-framed wall.
  • Cellulose fills and blocks air leakage through the walls better than fiberglass batts.
  • Plus, your home will be much quieter inside.

Project Cost

  • In 2008 and 2009, a Montgomery county tax credit was available to offset the cost of insulation by $250.
  • The total project cost on this house was about $7300, and included blowing cellulose into the attic, the sloping roof (the part with the melted snow in the first picture), a rear attic, floors of knee wall spaces, front and side walls (back walls were already insulated). It also included air sealing of the attic and kneewall spaces and the basement, a complete air sealing and insulating project.
  • The project was estimated to reduce total energy consumption by 23.92%
  • Natural Gas Heating savings were estimated at 38.7%
  • Air Conditioning Savings were estimated at 25.4%
  • The annual energy savings cost from the project are estimated to be $850
  • The annual rate of return on the $7300 investment is estimated to be 11.5%