How to Winterize Your Home and save money: part 2 insulation

Wednesday, October 14, 2009

Last time we talked about “Why not winterize your home and save yourself a lot of money”. Again we have been told our heating bills will go up again this year; so while it’s still comfortable outside, it’s a great time to get your home ready for winter. And besides, winterizing your home is much simpler than most people think.

 Insulating your atticThis time we are looking at the insulation in your home. Virtually every type of residential and commercial building in the country has insulation in it. Insulating is like putting on a warm winter sweater, while air sealing (which we talked about in part 1) is like putting on a windbreaker so that air doesn’t blow right through the sweater. Insulating is one of the cheapest things you can do to save energy.

Insulation works by slowing the flow of heat trying to leave your home by making it jump across millions of tiny air spaces. The smaller and more plentiful the air spaces, the better the insulation. Materials to choose from are closed-cell foam, cellulose or fiberglass. The material you use is your preference, though some are easier to work with than others as a homeowner. Fiberglass insulation is the most common insulation used for walls and attics.

R-Value is a measure of insulation’s ability to resist heat flow and the higher the R-Value, the better the thermal performance of the insulation. Here though there are some things you should know. Don’t compress the insulation when you install it as this reduces its R value. Typically R12 – R14 or 3.5” is good for walls and R30 – R40 or 10 -14” for ceilings. If you do not have this much insulation you really should consider adding some to bring it up to these values.

Fiberglass and cellulose are porous types of insulation so that air moves through, carrying moisture with it. On the cold side of the insulation this moisture may condense and cause moisture to collect on the inside of your roof deck. There are two things that control this.

a. Roof vents allow the moisture to be taken right outside and are needed both in the summer (to help keep your attic cool, and winter to get rid of moisture).

b. A vapor barrier keeps the water vapor in your house from condensing in the insulated cavities. Vapor barriers are installed on the side toward the living space because the moisture will otherwise enter the insulation and when it reaches the colder area, condense. If you install a vapor barrier on the cold side of the insulation you will have problems! Houses built in the 60’s and later will have a vapor barrier installed when constructed and unless you have stripped the walls or ceiling to the studs you will not be able to properly add a vapor barrier though you can and should add insulation and roof vents.

 Insulating your atticWhen you add insulation to attic rafters and attic floors, it’s important to maintain at least a 1” continuous air space between insulation and roof sheathing, from eaves to ridge. This air space allows air to move and move out moisture. It also helps maintain a “cold roof,” which prevents ice dams from forming in the winter and excessive heat from damaging shingles and increasing cooling costs in the summer. One of the biggest mistakes homeowners make with installation is to install it so it blocks the flow of air at the eaves. The best way to avoid this problem is to install inexpensive air chutes to keep the space open.

Installing insulation yourself can be messy, awkward and tiring. The experts can make it look easy, but it isn’t. This does not mean you can’t do it yourself.

Here are some tips:

 Insulating your attic a. Identify the type and amount of insulation you currently have.
b. Calculate the amount you need. This should be a simple square foot calculation.
c. Purchase the additional insulation you need from a building center where you can get help from the staff.
d. Make sure the existing insulation is dry and properly installed.
e. Also make sure the area is accessible and that you can maneuver around in it.
f. Make sure to allow for adequate ventilation. Never cover attic vents, and leave at least that one inch of air flow between the insulation and the roof talked about earlier. Any plans for adding roof ventilation needs to be done from the roof. Make sure you follow good safe practices.
g. If you choose fiberglass insulation, there are new “no-itch” products that are worth the extra cost. They’re much easier to handle and safer to work with.
h. Always wear protective clothing even though the attic could be quite hot, goggles, a dust mask or respirator, gloves, a hat, long sleeves and long pants when working with insulation. For the best protection, try tucking your sleeves into your gloves and tucking your pant legs into your socks.
 Insulating your attici. Be careful working in your attic. Walk only on ceiling joists. Walking or putting pressure on the ceiling itself will quickly make a hole in your ceiling (creating another job) and may cause you to be seriously hurt. Try laying a small plywood panel across the ceiling joists to walk or kneel on. Watch out for overhead rafters, and places to hit your head, (it may make you smarter, then maybe not).
j. Try not to disturb the existing insulation. Moving it around can create a lot of dust and leave gaps where air can leak through.
k. When adding batts of insulation, install them at right angles to the first layer but only if the existing insulation is full to the top of the joist. If the joist space is not full try putting a thinner layer in first to fill the joist spaces and then a second thinner layer across the joist. This will not cost more as insulation is usually sold by R value and square foot.
 Insulating your atticl. Never put insulation over recessed light fixtures as this may cause over heating and a fire. You must first build a box around them that leave at least 3” of gap from the fixture then you may insulate over that. Keep all insulation at least three inches away from chimneys and gas flue pipes.
m. Finally make sure you insulate and weather-strip the attic opening as you exit the attic.
Always follow the manufacturer’s instructions. Skipping steps and taking shortcuts could mean significant reductions in R-value – and a waste of your money and effort. Allow yourself plenty of time to complete the job. It is often tight, slow work and make sure you have enough materials to complete the job before you get started.

Through efficient ways of heating and insulating your home, you can reduce long-term energy costs and make more efficient use of the heat generated. Heating is one of the higher energy uses in our homes, and has the greatest potential for savings. One of the easiest ways to save energy on heating is to set the temperatures inside the house at comfortable but not excessive temperature.

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2 Comments

  1. Mike says:

    Excellent description and pictures of attic insulation – Especially interesting is the picture of the baffle around the recessed lighting can.
    Question: the picture seems to show insulation being laid over the baffle, which will hold the heat of the light inside the baffle. Is that what you meant to show? Or should I leave the space above the baffle clear of insulation?

    Thanks!

  2. Dave the How To guy says:

    Yes you can put insulation over the baffle provided you maintain a proper airspace around the light fixture. It does hold the heat in and that is what you want as you don’t want all the heat going through the roof. But if you maintain the proper airspace around the light fixture and that will vary depending on the fixture, the heat will disperse enough that the heat won’t be hot enough to overheat the wires and cause a fire. That was a good pick up on your part and a great question.

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