Whether you live in a warm or colder climate, insulating your home has many benefits from savings on energy bills to creating a quieter environment in your home. The average home owner spends half the costs of their total monthly energy bill on heating and cooling.
The good news is that you can boost the energy efficiency of your home to meet U.S. Department of Energy (DOE) recommendations, as well as state and local codes. And these relatively simple projects are affordable and can save you a lot of money allowing you to recoup your investment in your home very quickly, often times within a year.
But there are a lot of products on the market and it can be confusing if you do not know the lingo. After all, each one of those numbers on the side of package means something, so you need to educate yourself before embarking on any project.
This article will help you choose the best products for your home and after reviewing the project details, you can decide if it is a DIY project, or if you will need to hire a contractor.
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The purpose of insulation is to reduce the natural movement of heat from warmer to colder areas. There are also certain types used to sound proof or reduce noise and to control moisture.
What is the R-value?
R-value means resistance to heat flow. The higher the R-value, the greater the insulating power. The DOE bases its R-value recommendations for existing homes on specific heating and cooling needs and the cost of energy across the country within each zip code.
How do I determine my current R-value in my attic?
The attic is one of the easiest and most important areas of a home to insulate. The DOE recommends up to R-49 for attics in most areas.
To determine how much insulation your home might need, simply measure the thickness of your attic’s existing insulation with a ruler. Take the number and multiply by 3.14 to get the approximate R-value of what is in your attic now. Then check the chart above to see what the DOE recommends for your area of the country.
Why is ventilation important?
When your attic or crawl space is properly ventilated, a positive airflow is created, which allows the house to breathe and helps prevent moisture buildup when used with vapor retarders.
Where does the moisture inside a home originate?
Most of the moisture and humidity inside a home comes from a surprising amount of humidity put into the air from showers, cooking on the stove, washing dishes and clothing and even breathing. Vapor retarders on the warm side help control the amount of moisture collecting inside exterior walls, ceilings and floors.
How much insulation should I purchase?
- Multiply the length by width of the area for total square footage
- Measure the distance between joists or studs
- Choose appropriate R-value, thickness and width
- Divide total square footage by square footage per package, then round up to the next whole number to determine total number of packages required.
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Basic Tools for Insulating
- Tape measure
- Utility knife
- Stud finder
- Straight edge for cutting insulation
- Lightweight, squeeze-type stapler if installing faced insulation
- Portable work light for dark areas
- Sheets of plywood to sit in an unfinished attic surface on which to cut the insulation)
- Insulation supports if installing under floor in crawl space
- An instrument to push insulation into hard to reach areas in attics
- Work gloves, Loose-fitting, long-sleeved shirt
- OSHA-approved safety glasses
- Disposable dust respirator (NIOSH- or MSHA-approved)
Preparing the Insulation for Install
Leave fiberglass insulation rolls in their wrapper until you are ready to use it. Packaged insulation is highly compressed and expands when the wrapper is removed.
When cutting insulation, lay it on a flat area while using a yard stick over the area of insulation to be cut. Press your straight edge down hard against the insulation and cut with a utility knife using the straight edge as a guide.
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How to Improve Your Energy Bills
When adding a second layer of insulation in the attic, the unfaced type should always be used so that moisture is not trapped inside the bottom layer of insulation. Additionally, temporary flooring should be laid across the joists to provide some footing.
- Begin at the outer edge of the attic space and work toward the center. As with tiling a floor, you do not want to insulate yourself into a corner.
- If the cavity between the joists is not completely filled, use the appropriate thickness of insulation to fill it to the top, then add an additional layer of insulation in a perpendicular direction.
- The insulation should extend far enough to cover the tops of the exterior walls, but should not block the flow of air from the soffit vents.
- Stuff small openings with leftover pieces of unfaced insulation.
Note: Insulation should be kept 3" away from recessed lighting fixtures (unless they are marked I.C. (designed for direct insulation contact) and any metal chimneys, gas water heater flues or other heat producing devices. 
Faced insulation should be installed in the wall of a finished attic with approved ceiling, floor or wall material. Keep any open flames or other heat sources away from facing when you are installing.
- Do not place insulation within 3" of a light fixture or similar electrical device unless device is labeled for contact with insulation.
- Use only unfaced insulation between wood framing and masonry chimneys. Do not use insulation in spaces around metal chimneys fireplaces or flues.
Follow these steps to install insulation in a finished attic:
- Use separate pieces fiberglass Insulation for rafters and collar beams. Trying to fit a continuous length of insulation where collar beams and rafters meet may result in gaps.
- Staple facing flange to either the inside or face of framing to hold the insulation in place.
- When selecting and installing insulation for the rafter portion, 1" of ventilation space should be provided between the insulation and the roof sheathing.
- If insulation is to be installed in a flat ceiling, place it between joists by stapling facing flanges to the inside framing.
- Place the vapor retarder toward the “warm-in-winter” side of living area of the house in heating climates. In Gulf Coast states and Florida, local building practices may not call for an interior vapor retarder.
- Finish the walls and ceiling with an approved interior finish such as drywall or gypsum wallboard.
- Install faced insulation in end and knee walls.
- Staple the faced insulation so it will remain in place.
- Use leftover pieces of insulation to fill in small spaces around window framing, behind electrical outlets.
Interior Basement Wall
Use either faced or unfaced exterior wall insulation in basement walls with an R-value anywhere from 11 to 21.
- Faced insulation should be placed between the studs with the vapor retarder facing the interior of the room in heating climates.
- With either faced or unfaced insulation, an interior finish material such as drywall should be installed as soon as the insulation is in place.
Walls of Air Conditioned Crawl Space
The walls of a conditioned crawl space or one with uninsulated ducts or water pipes should be insulated with unfaced R-25 or R-19.
- Measure and cut small pieces and fit them snugly into the band joist or the area above the foundation wall.
- Cut long enough to cascade down the walls and extend 2' along the ground on the floor of the crawl space.
- Use long furring strips or cap nails to hold the insulation in place by nailing them to the sill. The nails should not be driven completely through the furring strips so that the insulation is compressed as little as possible, preferably to no less than one-half its original thickness.
- Spread a 6-mil polyethylene vapor retarder across the entire floor and tucked under the insulation that is touching the ground.
Open Air Crawl Space
The insulation should be installed all the way back at the end of each joist run so that it touches the band joist. You want complete coverage under the house.
- Insulation should be placed around cross braces by cutting it and pushing it between the braces.
- There are often both pipes and wires in crawl spaces under floors, and occasionally there will be a junction box.
- Water pipes should be insulated with foam rolls.
- To support the insulation under the floor, use flexible metal supports or wood furring strips
- Install a 6-mil polyethylene ground cover to keep ground moisture from seeping up into the space.
- Hold the polyethylene in place with bricks or rocks.
How to Insulate Your Home
Insulating walls and attics is a relatively easy project if the walls are already open and the attic is not finished, and is one of the cheapest ways you can improve your energy bills.
Always check with your local building codes for requirements in your area before beginning any home renovation projects and follow the safety precautions.
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