The crawlspace under our house seems abnormally cool in the summer and warm in the winter. My first thought is that the ductwork leaks, but a friend said it may be just radiating warm or cold air depending on the time of the year. What are your thoughts?
-Scott

Hi Scott,
If your crawlspace is enclosed, it will stay cooler in the summer and warmer in the winter than the outside air due to the more constant ground temperature, but it should not be excessively different as you describe. It’s possible that the ducts are poorly sealed, allowing air to escape, or that they were inadequately insulated.

To check, go under the house when the HVAC system is running and feel along the ducts for air leakage. Also, look for discoloration of the insulation or rusting of the ducts that could indicate a leak. Pay particular attention to the joints in pipes and where runs of ducts meet in case a pipe has become disconnected. Repair any leaks using duct mastic or metallic duct tape rather than standard cloth tape. You can also have a HVAC professional run a pressurized test of the system to check for leaks.

If your ducts are inadequately insulated, you may see condensation forming on the outside of the ductwork during the summer when humidity is high and the air conditioner is running. Poor insulation can not only increase your utility bill in winter and summer by up to 30%, but it may cause excess moisture in the crawlspace which can led to mold. According to the U.S. Dept. of Energy, ducts in unheated spaces should be insulated to an R-value
of R-4 to R-8 in warmer parts of the country, and an R-6 to R-11 in colder climates.

Another possibility is that your floor may need insulating. If so, install batts of fiberglass insulation between the joists in the crawlspace with the paper vapor barrier facing up toward the living area and hold it in place with support wires. For more on insulating under a house, see our episode (655) Scariest Utility Bill.

High energy bills are a concern of homeowners everywhere, but living through frigid Maine winters in a two-story house built in 1890 can pose a real challenge. To combat winter heating bills as high as $1,400 a month, Greg and Jennifer Quimby entered the Scariest Utility Bill in America contest sponsored by Jeld-Wen Windows and Doors. As the winners, their house was outfitted with new energy efficient windows and doors.

Infrared Energy Audit

Whether you live in Maine or Florida, there are a number of things you can do to reduce your energy bills. A good place to start is with an energy audit to find out where your home is lacking. John Cannamela of Infrared Survey performed an energy audit using a special thermographic camera.

The camera detects the amount of infrared heat radiation and converts it to a color spectrum with blue representing colder objects and red warmer. By examining the differences in the amount of infrared radiation that is given off, the camera can detect areas that have air leaks or lack insulation. As expected, one of the main culprits found in the energy audit of the Quimby’s home was the old windows.

Window Replacement

When the replacement windows from Jeld-Wen arrived, the existing storm windows, window stops, and window frames were removed, leaving only the casing and outer window stops.

A bead of caulking was applied around the stop, and the new energy efficient vinyl windows were put in place. Once the new window was level and plumb, screws were driven into the jamb to secure it. After the gap between the old casing and new window had been insulated, the original interior stops were put back and caulked.

For high energy efficiency, the new windows have dual-pane glass. The space between the glass is filled with argon gas to reduce the movement of heat between the panes. The glass also has a Low-E coating which deflects UV radiation and protects furniture and fabrics from fading. The new windows were made to match the existing two over two frames, which complemented the historic nature of the house.

Not only are the Quimby’s new windows and doors more energy efficient, the vinyl window frames will require much less maintenance than wooden frames.

Basement Insulation

In addition to new windows and doors, the homeowners took some additional measures to reduce their energy bills, including insulating between the ceiling joists in the basement. Since fiberglass insulation can cause irritation, be sure to wear a long sleeve shirt and long pants along with eye protection, a mask, and work gloves. Rubbing baby power on any exposed skin helps reduce irritation.

Start by cutting the insulation to length using a square and sharp utility knife. In older homes, where the spacing of the floor joists is irregular, the insulation may have to be cut to width as well. Use a straight edge to compress the insulation and act as a guide for the utility knife. Trim each piece so it’s a snug fit between the joists.

The paper facing on fiberglass insulation contains a thin layer of asphalt adhesive that bonds the insulation to the facing and acts as a vapor barrier to prevent moisture from passing through it. Since insulation should always be installed with the vapor barrier facing the heated living area of the house, when insulating under floors, the paper facing should face up against the flooring.

Hold the insulation in place by wedging insulation support wires between the joists. Wires can be cut to length if needed using wire cutters.

Other Energy Saving Ideas

To save even more energy, the hot water pipes were insulated with tubular foam pipe insulation to prevent heat loss.

The covers were removed from the electrical outlets on exterior walls and foam insulating seals fit around the plugs. The infrared camera showed that this significantly reduced the heat loss around electrical outlets.

Replacing worn door thresholds is another important step that can cut down on air leaks in a home. After cutting the new threshold to size, screw it in place and press the rubber gasket in the grooves.

More information on insulation and saving energy can be found at:

• Getting Adequate Attic Insulation
• Insulation R-Value
• Payback on Energy Saving Efforts
• Eight Great Ways to Save on Heating Costs
• Winterizing Your Home

Other Tips From This Episode

Power tools used on Today’s Homeowner with Danny Lipford® are provided by Ryobi.

Attics, basements, and crawlspaces are the least frequented areas of a home, which is one of the reasons they often cause the most problems. A regular inspection can catch potential problems—like leaks, condensation, termite activity, or the growth of mold—before they become a major headache.

Attics can become virtual ovens in the summer, so work in the early morning or wait until a cooler time of year. Inspect basements after a heavy rain to catch any leaks. And don’t neglect the crawlspace under your home if it’s built off the ground on piers. While it’s not the most inviting place to spend an afternoon, early detection might save you thousands of dollars in termite damage or rot that would otherwise go undetected.

Here are some of the most common questions concerning problems with attics and basements:

Attics

Is it necessary to install a separate vapor barrier between the living area of a house and the attic or crawlspace?

No, a separate vapor barrier is usually not needed since any condensation should be able to escape from a properly vented attic or crawlspace. For more information, see our article on Vapor Barriers.

Should the facing on insulation in the attic or under the floor go up or down?

Install insulation with the facing toward the heated living area of the house. In the attic the facing should go down against the ceiling while under the house it should be up next to the subfloor.

Should you install a layer of faced insulation in the attic on top of the insulation that is already there?

No, always put unfaced insulation on top of existing attic insulation. Since the facing acts as a vapor barrier, it could trap moisture in the insulation. For more information, see our article on Attic Insulation.

If I install a second layer of insulation in the attic on top of the existing insulation, which way should it run?

If the existing insulation is even with or higher than the top of the joists, the new layer should run perpendicular to the joists. If the existing insulation is lower than the joists, lay the new layer between the joists.

How much venting does an attic require?

A typical house should have one square foot of vent for every 150 square feet of attic floor space. Ideally, half the vents should be located in the soffit at the bottom of the roof and half in gable or ridge vents near the top to crreate a flow of outside air into the attic. For more information on venting your attic, see our article on Adding Soffit Vents.

What size should an attic vent fan be?

An attic vent fan should be large enough to completely replace the air in the attic every six minutes. To determine the size needed, calculate the volume of your attic in cubic feet and divide by 6. This will equal the rated capacity of the attic vent fan in cubic feet per minute (CFM). For more information, see our article on Attic Ventilation.

Can you cover electrical wires and boxes in the attic with insulation?

While recessed ceiling fixtures should not be covered, wiring and ceiling boxes for surface mounted or hanging light fixtures can be covered by insulation.

How can I prevent condensation in my attic?

Condensation can occur when heated air from inside the house condenses on cold surfaces in the attic. This can usually be prevented by removing any sources of moisture in the attic, and making sure there is adequate ventilation in the attic. Always vent dryers and bathrooms fans outside rather than in the attic, and check to be sure that soffit vents under eaves have not become blocked by insulation.

Crawlspaces and Basements

How can I prevent mold and termites in of the crawlspace under my house?

Mold and termites can be a problem under homes, particularly in warm humid climates. Since both need water to thrive, start by checking for any plumbing leaks, condensation from ductwork, or rainwater seepage. Cover the crawlspace with sheets of 6 mil black plastic, overlapping them a foot and taping all seams. Run the plastic up the sides of the foundation walls with holes cut for the outside vents. Use a flashlight to inspect the joists and the subfloor periodically for signs of mold. Check the piers and foundation walls for mud tunnels make by termites. For more information, see our articles How to Prevent and Remove Mold, and Formosan Termites.

How can I add a bathroom or laundry room in a basement?

Since plumbing uses gravity to drain, you will have to install what is known as a “grinder pump” or “lift station” to pump waste water up to the level of the drain pipe leading away from your house.

What can I do to keep my basement walls from sweating?

Start by taping a one foot square piece of plastic to the wall and sealing it around all fours sides with tape. If moisture appears on the outside of the plastic, the problem is condensation due to excess humidity in the air. If water forms behind the plastic, then water is seeping in through the walls. To prevent condensation, start by reducing the humidity in the air as much as possible by venting dryers and bath fans to the outside and eliminating any plumbing leaks. If problems persist, consider insulating the exterior walls or installing a dehumidifier. See below if the water is coming from outside the basement.

How can I stop a basement from leaking?

Start by being sure the land around your house is graded so rainwater is diverted away from the house. Install gutters and put extensions on existing downspouts. If that doesn’t help, you may have to excavate around the basement and waterproof the walls from the outside. For more information on basements, see our article Basement Refinishing.

Even if your attic is well insulated, the folding stairs that provides access can be a major source of heat loss. They often are poorly sealed and provide only a thin piece of plywood to keep the heated air from escaping.

Begin by checking to see if the attic stairs close tightly then apply self-adhesive foam weather stripping around the perimeter where the plywood door meets the frame, except on the hinge end.

Once the opening has been sealed, it can be further insulated by building a foam box in the attic to enclose the stairs.

Materials for the project cost around $30. Here’s what you’ll need:

Materials List:

• 1 – ¾” x 4’ x 8’ sheet rigid foam board
• 1 – 2” x 30’ roll foil duct tape
• 2 – ¾” x 17’ roll foam tape weather stripping
• 1 – tube caulking (optional)

Be sure to use foil tape since regular duct tape won’t hold up to the heat in the attic.

Start by measuring the dimensions of the opening.

And the height the stairs protrude above the attic floor.

Using a utility knife with a straight edge as a guide, cut strips from the sheet of foam to form the sides of the box. For best results use a new blade so it will cut the foam cleanly. Make the strips an inch or two wider than the stairs extend above the attic floor.

Finish the cuts by bending the piece and cutting from the other side.

Cut the strips to length to form the box using a framing square as a guide then join the corners with foil tape. A bead of caulking can be applied as well to form a better seal.

Attach foam tape weather stripping to the top edge of the box to form a tighter seal. Cut a piece of foam the size of the exterior dimensions of the box for the lid. Tape the lid to the top of the box along one of the long edges with foil tape.

Clean the floor around the attic stairs so the tape will adhere well. Position the box over the opening, making sure it is square.

Attach the box to the floor around the outside with strips of foil tape then run tape along the entire edge.

A bead of caulking can be applied around the inside of the opening to provide a better seal.

Finally, remember to close the lid when you leave the attic.

For those who would prefer to purchase a premade cover, the Attic Tent™ is available in several sizes to fit different openings.

One of the first steps in creating a green home is finding innovative, environmentally friendly products to incorporate into the construction or remodeling process. According to Brian Welch, the publisher of Mother Earth News, green products are those manufactured from nontoxic, sustainable, or recycled materials. They also include items that save energy or can be easily recycled. Here are a few green products worth considering for your home.

• Bonded Logic UltraTouch Natural Cotton Fiber insulation is made from recycled cotton material that has been treated with a nontoxic boron-based fire and mold retardant. It doesn’t release harmful chemicals into the air of your home and is free from the irritation caused by fiberglass insulation during installation.

  

• BioBased Insulation is an environmentally friendly spray-on expanding foam insulation made from soybeans. Since it seals wall cavities completely, it has a high R-value. The inert material doesn’t release harmful fumes like some other foam insulations.

  

• Solar Star attic exhaust fans from Solatube International have photovoltaic cells attached to the top of the unit and are powered by the sun. Though they cost more than traditional exhaust fans, installation is easy since no wiring is required, and there are never any operating costs.

  

• Majestic Slate plastic polymer roofing from EcoStar is manufactured from recycled rubber and plastic. It has the look of real slate with only half the weight and can stand up to hurricane force winds. Best of all it comes with a 50-year warrenty and can be recycled again when it wears out.

  

• HardiePlank® fiber cement siding from James Hardie Building Products is a green product that has become very popular in recent years. Made from cement, sand, cellulose fibers, and water; it is not only environmentally friendly but more extremely durable. It comes either primed or prefinished in a number of colors and is guaranteed for 50 years.

  

• SoundStop® is a sound deadening fiberboard from Knight-Celotex that is made from recovered hardwood and sugarcane fibers. The panels are attached to the studs before the drywall goes up and reduce the transmission of sound from the outside as well as between rooms.

  

Could you wrap your house with a plastic vapor barrier on the outside before you brick it? If not why, because I’ve heard you can on the inside? I know you can use a Tyvek wrap, so why not plastic? - David

David,

When warm moist air cools, it can become saturated and release some of its water vapor in the form of condensation. If this occurs in the walls of your home, it may lead to the growth of mold or cause wood to rot. Vapor barriers, like plastic sheeting, prevent the passage of both liquid water and water vapor while housewraps, such as Tyvek Homewrap®, stop liquid water but allow water vapor to pass through.

In colder climates a vapor barrier is used on the inside of walls to keep warm moisture laden air from escaping during the winter. Installing a vapor barrier on the outside could cause moisture to become trapped behind it or condense in the walls.

In warm humid climates, the use of a vapor barrier on the inside is not recommended since it could have the opposite effect during the summer when the house is air conditioned. This is not as big a problem as in cold climates, however, since the temperature difference is not nearly as great.

Along the coastal southeastern United States, it is now recommended that a vapor barrier be omitted on the inside and put on the outside, though most builders use housewrap instead. In the middle regions of coastal Southern states, vapor barriers may be omitted completely. Other parts of the country, particularly colder northern states, should install a vapor barrier on inside walls and housewrap outside. Further information, including a map showing the recommendations for vapor barrier use, is available at the U.S. Dept. of Energy website.

Vapor barriers are not considered as important under floors or in ceilings, since attics and crawlspaces are usually vented to the outside which allows condensation to escape without becoming trapped.

My house attic is insulated, but I noticed that the attic over the carport is not insulated. The carport is open on two sides. It joins the main house and both attics are open. Does it matter if the carport attic is not insulated? - David

Hi David,

No, it’s not a problem at all. Since the air in the shared attic space is not heated or cooled and is vented to the outside anyway, it doesn’t matter if the area over the carport is insulated. In fact it is better that it’s not in order to lessen the possibility of moisture condensing in that part of your attic.

Every year around this time we hear about ways to save money on heating bills, but how long does it take to actually recoup the money spent on these investments? While all efforts to drive down the cost of keeping your home comfortable this winter have value, some pay off a lot quicker than others.

The following examples are based on a home in average condition that is approximately 20 years old with 2,000 square feet of living space.

1. Caulk and weather striping: It’s always a good idea to seal any cracks or gaps around your home’s exterior walls to keep warm air from escaping or cold air from entering. Cracks around exterior windows, doors, fireplaces, electrical outlets, water faucets, and dryer vents can add 10%-30% to your home heating bills. Seal cracks with caulking and use aerosol cans of expanding foam to fill larger holes. Examine weather stripping on windows and doors for damaged or worn areas and check thresholds for a tight seal.

   Cost: $30.00
   Payback: 5 months

2. Install a setback thermostat: Replacing your existing thermostat is simple to do and the savings can really add up. Programmable thermostats can be set to automatically turn down a few degrees when you’re sleeping or away from home, saving up to 20% on your heating bills this winter.

   Cost: $60.00
   Payback: 8 months

3. Service heating system: Having a professional heating contractor clean, service, and adjust your heating system will make it last longer and perform more efficiently. Regular maintenance—along with changing the filters regularly—can save 5% on heating bills.

   Cost: $80.00
   Payback: 4 months

4. Add attic insulation: At least half the homes in the U.S. do not have sufficient insulation in their attics. Southern homes should have at least 12” while homes in colder climates need a minimum of 15”. Rolls of additional insulation can be installed by the homeowner, or a company can be hired to blow in loose insulation.

   Cost: $900.00
   Payback: 4 years

5. Replace Windows: If you have single pane, low quality windows, you can improve the energy efficiency of your home greatly by replacing them with Energy Star rated double pane units. Though the initial cost is high, it is estimated you’ll save between $125 and $450 a year in energy bills. Not only will you save money and be more comfortable, but replacing the windows will increase the value of your home as well.

   Cost: $4,200.00
   Payback: 9 years

How well insulation works is expressed by its R-value, which measures resistance to the flow of heat. The higher the R-value, the better it insulates.

How Much Is Enough?

The amount of insulation recommended for your home is dependent on where you live, but here are some general guidelines:

• Attic: Houses in a cold climate should have a minimum of R-49 in the attic, which is equivalent to approximately 15″ of fiberglass insulation. Warmer climates only require an R-38, or about 12″.
• Walls: While wall insulation is limited by the width of the studs, different materials provide higher or lower R-values. Fiberglass batts for standard 2×4 walls are now available in low, medium, and high density products that range from R-11 to R-15. Sprayed foam insulation in the same wall cavity can range from an R-14 to an R-28 depending on the product that is used.
• Floors: While there are additional considerations—such as venting and moisture problems—to take into account when you insulate under floors, the United States Department of Energy recommends an R-25 rating in cold climates and an R-11 in warmer parts of the country.

Installation

You can hire a professional to blow in loose insulation, or you can install rolls and batts yourself. If the attic isn’t insulated, cut the batts to fit in the space between the ceiling joists. If there is already insulation up to the top of the joists, roll out the new batts perpendicular to the joists.

If you choose to do the work yourself be sure to wear a long sleeve shirt, gloves, eye protection, and a particle mask. Don’t attempt to work in the attic during the heat of the summer, and be careful not to step through the ceiling!

More information is available at these U.S. Department of Energy websites:

• EERE Energy Savers - Insulation
• EERE Consumer’s Guide to Insulation and Air Sealing

Related Articles

• Getting Adequate Attic Insulation
• Attic Insulation
• Prevent Fiberglass Insulation Itch