How to Insulate Your Attic, Save Energy and Lower Your Power Bill
How to air seal and insulate your attic so your home does not lose all the heat it needs to keep you warm this winter. Getting your attic up-to-speed with insulation is one of the most cost effect measures to help your home be more energy efficient.
by Don Ames
Going to the attic usually means one of three things.
1. Your 10 years old and playing hide-and-seek.
2. Your 32 years old and you have one more valuable heirloom to store away for ever.
3. Your 54 years old and you’ve noticed a wet spot on the ceiling and you’re afraid the roof is leaking.
All these are good reasons to enter the attic, but for now, let’s enter the attic to look at the insulation and determine if adding more insulation would be a good – house warming – lower the power bill – thing to do.
Building codes effecting insulation levels did not really start to take affect until the early 1980’s. If your home was built prior to 1984, there is a pretty good chance that your attic has minimal attic insulation. Builders in the 1940’s did not insulate much of anything, builders in the 1960’s filled the space between the roof rafters with about 4 inches of insulation. Builders in the 1990’s installed 8 inches ( R-25 to R-30 ) of loose-fill fiberglass insulation and by the year 2000, insulation levels had reached 12 inches ( R-38 ). Today, depending on the homes location, attics are being insulated with 16 inches of blown-in fiberglass ( R-49 ), cellulose, or shredded blue jeans.
Yes, shredded blue jeans, I’m serious, the ripped up blue jeans were being installed in a wall as insulation.
Attic insulation is energy efficient if you live in a cold climate and you’re trying to keep the warm in and the cold out, or if you live in a warm climate and you’re trying to keep the cold in and the warm out.
Dark colored, metal fiber appearing insulation is probably rock wool. A popular attic insulation in the 50’s and 60’s. Fairly effective and not a health hazard. However, insulation granules that are roughly ¼ inch square that feel like Styrofoam and contrast from mirror shiny to dark in color might be vermiculite asbestos. This is bad stuff because of the asbestos content. My advise to attics with vermiculite is to have it professionally removed. Do not handle or disturb this insulation without the direction of a professional contractor.
If your home was built prior to 1940, you need to be aware of knob and tube wiring. This is clothed bound wiring that is attached to ceramic knobs as it runs over wood framing structures or runs through ceramic tubes when the wire runs through holes in the framing or building material. This type of wiring will need to be replaced by new electrical wiring by an electrician before insulating. If you insulate directly over knob and tube wiring, the wire can heat up and create a fire danger.
One more thing, watch where you step when in the attic, only step on the truss or rafter framing lumber. If you step between the framing members you are likely to stick your leg through the ceiling and have one ugly hole to patch and one heck of a mess to clean up before the little women gets home.
Tip – to provide a place to put your feet while you work on sealing the attic floor, take a piece of plywood into the attic that will reach over several rafters.
Tools and materials needed:
1. Basic face mask and light coveralls. Cloth or leather gloves and eye protection.
2. Drop light so you can see what you’re doing and where you’re going.
Tip – miner style head lights work good here.
3. If you have a flue or chimney running up through your attic, or recessed lights or ceiling fans, you will need a small roll of light weight metal flashing, 18 to 24 inches wide. One pair of tin shears.
4. Can of insulating expanding spray foam.
5. Tube of inexpensive general purpose caulk and a caulk gun. If you have gas appliances, also pick up a tube of high temperature caulk.
6. Cardboard vent chutesfor placing between the roof trusses at the same location as each eve vent or bird block. Count how many you will need by counting the number of eve or soffit vents from outside the home. The easiest tool to install the chutes is with a squeeze or tacker stapler.
8. 1/4 inch, #6 sheetmetal screws and a cordless drill.
Tip – get self starting and threading screws.
How to prepare the attic before installing insulation:
1. Remove the items you have stored in the attic that have been placed over the heated area of your home where you are going to insulate. Items stored over the garage can stay. Boards that have been placed in the attic to store items on also need to be removed.
Tip – Have a garage sale.
2. Take the vent chutes and the tacker stapler and install a chute at each location where there is an eve vent. Fit the chute so insulation can not block the vent and a flow of air can move from the outside, through the eve vent, up through the chute and out into the attic. Attic ventilation is important for the health of your attic.
3. With pieces cut from the roll of metal flashing and the high temperature caulk, seal around the flue pipe where the pipe comes through the ceiling. Cut a half circular pattern from the edge of the metal and install around the pipe like a collar, screw in place using the sheet metal screws by screwing through tabs bent up on the sides of the metal and screwing into the framing members of the truss. Place one half collar on one side of the pipe and a half collar on the other. Caulk the space between the flashing and the pipe with the high temperature caulk.
Tip – when working with the thin metal, wear gloves to avoid getting cut by the metal.
4. Now take the metal flashing and the tin shears and form a cylinder around the flue pipes and masonry chimneys and anything else that carries hot combustion gases. There should be a two inch air space between the hot flue and the new sheet metal insulation barrier. Use the sheet metal screws to hold in place. These cylinders should look like extra tall turtle neck sweaters on a metal neck.
5. If you have recessed lighting or canned lights ( same thing), locate them in your attic. Older canned lights that you cannot cover with insulation will not be IC rated. IC stands for Insulated Ceiling. The IC rating should be clearly indicated on the label attached to the back of the light. Do not confuse a UL rating ( Underwriters Laboratory ) with the IC rating. They are not the same thing. A UL rating means the canned light has a cutoff switch installed that will turn the light off if it gets too hot. An IC rating means it is safe to cover the canned light with insulation. Air space between the IC rated light and insulation is not needed.
Tip – Now would be a good time to upgrade the recessed lights to sealed cans and IC rated.
If the canned light is IC rated, seal the light where it comes through the ceiling with general purpose caulk – your ready to install insulation over the light.
If the canned light is not IC rated, seal the light where it comes through the ceiling and any holes in the light body with high temperature caulk. Form a cylinder with the metal flashing and place it around the light body like you would a flue pipe leaving a two inch air space. Hold it in place with the sheet metal screws. This should look like a gardener that puts an open end bucket over his young tomato plants so they are protected from the cold. The plant is the can light and the bucket is the sheet metal.
6. Locate any exhaust fans, there could be none, one or more. The fans should have a ridged or flexable round duct running from the fan to an exhaust point that puts the exhausted air outside and not in the attic. Use the all purpose caulk or the foam spray to seal the fan body at the ceiling. Use the caulk to seal the holes in the fan body. Be sure the duct is exhausting to an eve vent or a roof peak vent. Use the metal flashing and the foam spray to seal the exhaust duct to the eve or roof vent. Support the duct with wire or plastic ties to be sure that the duct does not fall down over time. An exhaust fan has a one way flapper valve in the exhaust fan body just before it attaches to the duct. Given the chance, inspect the flapper valve and make sure lint, dust, hair, moisture and gunk has not left the valve stuck open or glued shut. The flapper valve is a back flow restrictor, keeping cold or warm air from coming back down the duct into your house.
Tip - Now would be a good time to replaced older noisy exhaust fans. I recommend an exhaust fan rated at 100 cfm (cubic feet per minute ) or more and on the quiet side.
7. Now take the can of spray foam and apply foam to every hole where an electric wire, T.V. wire, or telephone wire enters or leaves the attic. Do the same for the plumbing pipes. There should be vent p ipes running up from the attic floor and out the roof. Foam where the pipe comes through the attic floor. Do not foam where the pipe goes through the roof.
8. Some homes, both older homes and newer, may have open framing spaces that run from the attic floor down to the floor below. These are spaces that result from unneeded space at the end of bathtubs or closets. They maybe the result of irregular framing such as a triangle formed where a closet meets a hallway that meets a bedroom door. These open chases need to be sealed with more than just insulation. Take a piece of cardboard, cut it to fit over the opening, lay a bead of all purpose caulk around the lip of the opening, lay the cardboard on top the the caulk and screw down with the sheet metal screws. Now you simply insulate over the cardboard.
Ready to insulate
Tools and Materials Needed.
1. Tape measured- for calculating the square footage in your attic and for marking cardboard strips with the depth of insulation you want to add.
2. Insulation – fiberglass is a glass product, cellulose is a paper product. Either one is good.
Tip – fiberglass is itchy, cellulose not so much.
3. Insulation blower - Large hardware and building stores will have a blower you can use if you buy the insulation from them. Don’t forget to call ahead and reserve the machine. The blower comes with about 2 miles of hose.
4. Utility knife - for cutting open the packages of insulation.
5. Attic access tent- This is a rarely new item for insulating over the attic access opening after you have insulated the rest of the attic.
6. 1/4 inch self adhering foam weatherstripping. Small roll about 12 feet long.
7. Gate latch - two small gate latches for holding the access lid down.
8. One friend – flip a coin, one person to spray the insulation in the attic and one person to feed the machine in the garage or back yard etc.
Take the tape and measure the length and width of the attic space. This can usually be done from outside the house by walking around on the lawn instead of in the attic walking around on narrow trusses. Plug the numbers into a calculator with a multiplication sign between them and calculate how many square feet are in your attic.
Take a trip down to your favorite hardware store and head for the insulation department. The bags of insulation for loose fill or blown in insulation will be square compressed packages. Grab a package and read how much insulation is in the package at a certain thickness or depth. The chart on the package will allow you to calculate how many packages of insulation you will need if your attic is so many square feet and you want to add so much R-value. For instance, one package will cover 100 square feet at R-16, 56 square feet at R-30, and 32 sq feet at R-49.
Tip – purchase a bundle or two extra, once you start blowing insulation you don’t want to stop to go get one more bundle.
Load up the blower and the insulation in the back of the pickup and head home for a great, energy saving day.
Set the blower in a handy location. You will need to plug the machine in to an electric outlet, feed it with bundles of insulation, and run the hose from the machine to the attic. Tack up a few of the cardboard depth indicating strips that you made so you have a target depth to aim for. Start in a back corner and work your way to the attic access opening. Spray the insulation from the hose in a sweeping motion that allows the insulation to fall on your attic floor like a fine light snow. Fill one section of attic to the intended depth before moving on to the next section. Be careful not to direct the flying insulation into the eve chutes or inside the cylinder barriers.
Tip - If your attic has an electrical junction box or some other fixed item that will be hard to find once covered with 16 inches of insulation, mark it’s location by writing on a piece of cardboard and stapling the sign above the item on a roof rafter with an arrow pointing the way.
Fill the entire attic with nice new insulation to an even thickness indicated by the cardboard depth measuring strips placed effectively around the attic. Once you have all the attic filled except just the area around the attic access opening, stop for a moment, take some cardboard, and install an insulation barrier around the opening. Now you can add insulation to the proper depth right up to the opening.
Tip – Plan ahead so the hose and the blower hopper is not full of insulation when you are finished and need to take the hose off the machine.
Hey, you’re almost done.
1. Spread the attic access tent over the opening.
2. Attach the 1/4 inch self adhering weatherstripping to the contact perimeter of the lid that fits into and covers the access opening.
3. Install the hatch latch clips, one on each side of the lid in such a manner that when the latch is fastened, it pulls down on the lid and compresses the weatherstripping so the lid is air tight.
4. Load up the extra bundles of insulation and the blower and return to the store.
There is bound to be a light sprinkling of insulation under the access opening and around the area where the blower was located. Brooms do not work real well on insulation in grass or carpet. Grab the vacuum cleaner and don’t stop until your sure you won’t need to sleep on the couch.
You will now receive the satisfaction of a lower power bill, a warmer feeling, less drafty home, and a furnace that does not need to work so hard. Hope this article has been a help, please come back soon and hurry, I won’t be leaving the light on for you…