Unless your attic is finished, your attic space is essentially just outside your house’s enclosed thermal envelope. Heated air rises and conducts that heat into the structure and air of your attic and from there to space. Only one thing efficiently maintains and spreads the preferred temperature inside your house: insulation.
Heating and air conditioning account for 50 to 70% of the energy used in the average American home. Inadequate insulation and air leakage are leading causes of energy waste in most homes. Air sealing won’t benefit a whole lot if there is insufficient insulation for the whole house. Throughout most of the country, the US DOE recommends at least R30 (about 1 foot of blown cellulose or fiberglass) for attic insulation and a minimum of a R13 (a bit more than 3 inches of blown cellulose or fiberglass) in the walls. (http://www.ornl.gov/sci/roofs+walls/insulation/ins_06.html) Unfortunately, most homes built in the past two decades are built with R13 in the walls and attic; few have R30 in the attic.
Let’s say your home has R13 of blown cellulose insulation in the attic. The attic measures 1750 square feet and we’ll assume that the insulation has settled. To bring it up to at least R30, we need to add a further 17 R-value’s of insulation to the attic. The easiest way to do this is to either apply another 5 inches of blown cellulose or put down un-faced R19 fiberglass batts (about 6 inches thick).
To figure the cost for blown cellulose to cover the attic space, multiply the square footage by the thickness. Therefore: 1750 × 5 inches (or .416 feet)= 728 cu ft. The home center sells bags that are 16 cu. ft. Divide the 728 cu. ft. by 16 cu. ft and you get 46 (16 cu ft) bags. Some home centers may include the free rental of their blowing equipment as an incentive; others may not. To make the insulation work effectively, it must be spread evenly throughout the attic so that no thin spots or hollows are formed. Also, to keep the insulation out of soffiting, dams need to be built and installed at the end of each ceiling joist (or around light fixtures) before turning on the insulation blower.
Fiberglass insulation is typically figured by square foot. Rolls of R19 come in 23 inches wide or 16 inches wide. This is so the insulation fits between the joists. Roll lengths vary, usually between 48 and 77 feet long (though batts are available). What you should watch out for is just how big the roll is. In other words – can you get it through the attic’s entrance or trap door?
Once you’ve decided on what size works for you, divide the square footage (our 1750 square feet) by the length and you have the number of rolls you need. Craft-faced insulation has a paper vapor barrier facing. Because insulation is being added on top of other insulation in this case there is no need for the paper vapor barrier facing. While it is more expensive that the blown cellulose, fiberglass batts are convenient sizes that can be positioned and laid in place or trimmed as needed. And it’s always better to have extra.
Now, let’s say you’ve figured out how much you need…and that you can’t afford more than $ 50 at a stretch. Not to worry. The great thing about insulating is that it doesn’t need to be done all at once. You can take your time and build on it. The best way, though, is to figure out what area of your home you want to insulate first. Consider these two things: where is your thermostat located and where do you spend most of your waking hours in the home? Usually, the thermostat is in the living room and that’s were most people spend their time. The solution is simple here: lay in your first bundles of insulation over this room. But if your thermostat is in the living room and you spend your time in another room, such as a home office, you may wish to divide your insulation between the area over the thermostat and the office. In this instance, it’s best to take time to choose what priorities fit your lifestyle and how to proceed from there.
The autumn is the best time to install insulation in your attic. After all, during the summer, it could reach as high as 150° F, especially in a poorly ventilated attic. But, if you want to start saving money now during the peak heating season as well as later on during the air conditioning season, now is the best time to do the job. So, here’s some tips on how to make the job easy:
*Know your attic’s layout and plan how to fit the insulation in place in advance.
*Buy your insulation the day before you plan to install it. Moving around and working in a cramped space takes up an awful lot of time. Start early.
*It’s a dirty job. Be sure to wear long sleeves and pants, gloves, safety glasses and respiratory protection against dust.
*Get some help so you can get in and out of the attic faster. The job will go much faster and you both will have someone to complain about the dust to.
*Take some 2 foot by 3 foot pieces of 3/4 inch thick plywood into the attic with you. Use them to stand or kneel on as you move through the attic. Often you’ll find it’s easier on your shins and knees to rest on the plywood rather than balancing on a joist and risk crashing through the ceiling sheetrock into the bathtub.
*Start at the far end and work your way back to your attic’s entrance. Insulation works best if it stays “fluffed up” or not compressed. You don’t want spend time putting it down nice and neat and tight only to discover that you must trudge across it to get out of your attic.
*When you are done, take a warm shower to remove the fibers, dust, and dirt that adhered to your skin.
*When you’ve finished insulating the attic, you will also want to make sure your attic trap door seals. As mentioned, your attic is just outside your home’s thermal envelope so your attic door is really a door to the outside. Make certain that it closes snugly and seals. Use weather stripping – it will make a difference.
Heat Shield to Maximum!
Your roof is a heat shield for your house. But in order for it to work at peak efficiency, it needs to be adequately ventilated. The National Roofing Contractors Association recommends 1 square foot of ventilation opening should be provided for every 150 square feet of ceiling area. (http://www.nrca.net/consumer/fyi.aspx)
If you’ve ever ventured into an attic on a sunny summer day, you know how hot it can be. Temperatures can easily reach 150° F. Trapped heat increases your air conditioner’s heat load. This raises your energy costs. Trapped heat also can damage the plywood sheathing, under-layment, shingles and personal items located inside the attic.
Roof ventilation works with two kinds of vents, an exhaust and an intake. Heated attic air flows out through a vent in the upper part of the roof. This pulls in cooler air to enter through intake vents located down in the soffiting or fascia board. Most houses built in the 1960s onwards use a combination of soffit vents and either gable vents, roof vents, or ridge venting to allow air to flow through the attic. By allowing the attic to breathe and circulate heated air out, the house is better able to let go of the heat it absorbs during the day.
Retrofitting roof vents is not as hard as it sounds. Nevertheless, it can be daunting to climb onto your roof and cut holes into it. I have found the easiest to install is the ridgevent system. Ridgevents come in metal or plastic kits. It has a hollow inside and either vents along its sides or under a flange. By straddling a slot cut though the sheathing at the roof’s ridge or peak, it allows heated attic air to leave without letting rain inside.
The actual installation technique varies slightly depending on the kit you use but very basically remove the top cap of shingles on the roof, and use a circular saw to cut a one inch wide piece of sheathing from either side of the roof’s ridge. If you’re installing full length venting, you’ll be cutting two slots the entire length of your roof so use a sharp blade and take your time. Afterwards, attach the ridge vent and caulk down the loose ends.
Now that you’ve seen what to look for in your home thermal envelope, you can start planning where to begin, whether it’s walls, ceilings, foundation, floors, windows, doors, or the roof. And while it’s import to consider how your home works as a whole, approach improving it one step at a time. Dividing the project of sealing your home into smaller, manageable jobs around the house makes it easier to tackle. Consider that all these jobs don’t need to be done all together all at once. Tackle ridgevents one weekend, insulation another, or a new thermostat some weeknight after dinner. You should notice more energy efficiency — however slight — after each improvement. They will add up and you will save money and your home will feel more comfortable. But be sure to take your time preparing and researching, read the instructions, and use good tools.
Above all, be careful when considering projects that seem beyond your skill level. If in doubt, hire a professional. After all, sometimes doing-it-yourself can really do-it-to-you.
By adege from Pixabay