Foiling Around in the Attic

The roof of  most homes is designed to protect the structure of the building from the elements. It is like a “carport” for the home because it is not heated and the air is allowed to flow though. To protect the home from both heat loss and heat gain most homeowners use insulation between the ceiling joists.  In many southern areas of the country where it is hot for most of the year an attic can be as hot enough to melt wax, 160 to 190 degrees Fahrenheit. For homes in these parts of the country an insulated attic is a relief but more help is needed.

For heat relief in the attic many homeowners will put in an attic fan. This also keeps the air flow moving in the space but in northern areas it may forcibly cool down the attic and, in turn, the home. A better way to either keep heat away from your attic, or keep the heat in your home, is through a radiant barrier.

Radiant barriers use layers of aluminum foil sandwiched between thin plastic to reduce radiant heat coming into the attic. By attaching the barrier to the underside of the roof deck the reflective properties of the barrier will repel up to 97% of the heat which can decrease the temperature below over 30% and save up to 12% in air conditioning energy.

For keeping heat in a home the radiant barrier is placed right on top of the existing insulation. However, it is best to use a foil product with perforations so that moisture will not get trapped below and cause other problems such as mold. For attics without a lot of insulation there are products where the foil is backed with an insulating product like fiberglass or bubble-pack. These products come in rolls and are easy to install.

In other applications foil barriers can be used as a vapor barrier on a newly-studded wall. Not only does it do the job of a vapor barrier it will reflect heat back into the room or, in an air conditioned home, keep it cool.

Insulating With Cellulose

Up until the post World War II era it was widely believed that a dead air space between the exterior and interior walls would sufficiently protect the home from outside cold in winter. As air is a good insulator this was thought to be a sound idea. However, air can also be a good agent for transferring heat from the inside to the outdoors.

Today heating and air conditioning accounts for between 50% to 70% of the energy cost of a home (Department of Energy statistic). With the cost of heating almost doubling in the past few years this makes protecting the energy a primary concern. So that heritage home from 1910 may be an energy black hole.

Heat has three main ways of getting around: radiation, conduction and convection. Radiation is how the heat travels through the air like the sun’s heat or the heat from a register. Conduction is how a pot is heated. the energy travels via solid molecules. Convection is the cycle of heat moving from warm to cold and this is the most important factor in home energy.

In the winter heat will move inside the home in a convection cycle, from the the warm areas to the cold. For example, heat will go from the living room to the attic and outside or from the kitchen to the garage and out. In most homes the heat will go up and find cold spots on the ceiling or walls. So if there is no insulation in the walls it will penetrate the wall through conduction. Once inside the wall the temperature from the cold exterior wall will create an air current with the warm air called convection. This speeds up the heat transfer to the outdoors. In the summer this cycle is reversed promoting the use of an air conditioning unit.

The immediate need is to stop this cycle with insulation. In a newer home fiberglass batts fill these spaces so not only is the air movement curtailed but the transfer by conduction is slowed. This impediment for heat loss is called the R-value of the wall. A low R-value means there is more heat loss so most new walls have an R-value of 19 whereas the old homes with no insulation were at about 3.

To fix an old home the attic should be brought up to R-40+ with fiberglass batts or blown-in cellulose insulation. However, unless the interior walls are taken off it is difficult to use fiberglass batts. This would mean removing the old lath and plaster. These homes can be insulated from the exterior by using the blown-in insulation.

1. Find the Spaces: At the top of the out side wall a shingle is lifted and a 3″ hole drilled (door knob bit). If it is clapboard then the hole will have to be drilled through the board and the plug replaced. To find the voids look at the old nail heads. They will show where studs are located.

2. Drill Holes: With a plumb bob or heavy metal object tied on a heavy string lower this down through the hole until it touches bottom. This will show that the void goes the full vertical length of the wall. If not, another hole will have to be drilled below the place where it stopped. This can be measured by marking the string at the hole and measuring from the mark to the plumb bob.

3. Calculate the Amount of Cellulose: When all the holes have been drilled rent the cellulose blower. The cellulose comes in compressed blocks that cost around $10 each. Many companies will charge a bare minimum for the machine if the cellulose is bought there. Take the measurement (square feet) of the walls and add them together for the total amount of cellulose blocks to buy.

4. Installing: A person should handle the sprayer while a helper is needed to feed the blocks into the machine. Both should where a particle mask and goggles because the fines from the cellulose can be hard on the lings and eyes. The helper breaks up the blocks and feeds them into an agitator. The installer has a remote switch to turn on and shut off the flow. When each wall void is filled the cellulose will shoot out of the hole. The installer shuts off the flow and moves on to the next hole.

5. Replacing the Plugs: The round wooden plugs can be replaced by caulking the edges with a latex sealer. Glue will work but since the plug is slightly smaller than the hole caulking has the bulk to seal it. The shingle is put back or, if clapboard, the plug edges are smoothed over with caulking and then touched up with paint.

8 Basement Insulation Tips

With the price of a barrel of oil going through the ceiling homeowners are beginning to have home inspections done to find out where they need extra protection against losing heat. What many people don’t know is that much heat is lost through drafts than through poorly insulated walls.

1) Rim Joists: The joists sit on a sill plate which is a 2″ X 6″ sitting attached to the tops of the foundation. The ends of the joists are covered with a rim joist which caps of the joists and seals the basement from the exterior. In most cases this is insulated and sealed but in many instances it is not. As wood shrinks and expands the motion pulls against the nails and minute spaces can occur. These breeches are large enough for cold drafts and moist air to enter the basement and should be sealed with a foam spray.

2) Basement Windows: Old wood-framed basement windows can deteriorate from moisture. Fissures can occur in the sill and sashes and between the sash and the cement foundation. These should be replaced with a vinyl product and a window well placed in to draw off the moisture. Newer windows should be caulked.

3) Basement Door: All door jams should be re-caulked with foam and the weatherstripping between thye door and the jam renewed.

4) Hot Water Tank: Tanks are only filled with minimal fiberglass insulation so this should have a jacket attached which can be purchased at a home supply store for around $45. Depending on the size of the tank the energy savings will pay this back in 1 years.

5) Pipes: Foam pipe inserts are easy to installed and will prevent heat from dissipating from the pipe and drawing it from the hot water tank. It also lessens the time for the water to get hot at the tap.

6) Duct Insulation: When the hot air leaves the plenum in the furnace it has to heat up the metal duct around it. Duct sleeves keep this heat within the system and does not allow it to cool.

7) Floor: If you can’t afford to insulated the floor here is a good place to put your old carpet. It will keep the heat from getting to the cement.

Walls: Set up a schedule to insulate all bare cement walls by stud frames and fiberglass or with foam sheets. Closed cell foam insulation does the best job because it seals everything.