Insulation is one of the most effective ways to improve the comfort and energy efficiency of a home. Insulation has a noticeable effect on both home comfort and energy usage, and there are usually incentives available from Energy Trust of Oregon to lower the installed cost .
Insulation is installed in three areas: Ceilings (attic floors), Walls, and Floors. The importance of each area varies depending on the construction of your home. Generally the goal is to insulate the outer edge of your heated living areas. Imagine a cross-section of your home, any living area surface that is adjacent to the exterior or an unheated space (such as a crawlspace or attic) should be insulated.
Is Your Home Insulated?
Homes can generally be divided into two categories: those built prior to the 1974 oil crisis and those built after. Homes built after almost always have some insulation in the ceiling and varying applications in floors and walls. The quality and quantity of this insulation has improved steadily since the 1970s to today's construction in which most codes require thorough and thick insulation of the entire building envelope. If you live in a home built from the 1990s to now, your home is probably well insulated and you should focus your efficiency efforts on mechanical systems like your furnace and water heater.
Homes built before 1974 vary wildly in their insulation. There was very little insulation used in most original construction so the presence and quality of insulation depends upon the efforts of individual homeowners over the years. It's a pretty safe bet that a pre-1970s home offers multiple opportunities for improved insulation that can significantly increase energy efficiency.
Ceiling Insulation
Ceilings are the most important place to have good insulation since heat rises. Checking for it is simply a matter of putting your head into the attic.
No Insulation Light Insulation Good Insulation
Measure the amount of insulation and compare it to this chart of recommended insulation thicknesses. Generally speaking, If there's space to add up to an R-38 level that will maximize your efficiency. Keep in mind there can be electrical and ventilation issues to address, along with sealing any gaps or penetrations, before adding insulation. See the "Planning and Safety" section below.
Verifying the presence and quality of insulation can be complicated in some instances with no direct access such as walls and sloped or vaulted ceiling areas. Sometimes these areas can be viewed at gaps around electrical boxes for switches, outlets, or lights (these gaps should be sealed). You can also check with previous owners if they are accessible, cut holes in the surface to see behind, or hire an inspector with a thermographic imaging camera which can detect voids in insulation.
Wall Insulation
Wall insulation is not as effective as ceiling insulation because it is limited in its thickness by the depth of the wall and there are so many openings (doors and windows) in the walls. However, well installed wall insulation is still an important step in creating a blanket around the conditioned living spaces of a home and there are usually incentives available for its installation.
Wall insulation is most effectively installed when the wall cavities are open during construction or remodeling. Wall insulation can also be retrofit into older homes using various "blow in" approaches to force insulation into the wall cavities via holes in the walls usually at the exterior but sometimes at the interior.
Wall insulation can be difficult to verify. Sometimes patched blow-in holes are visible at the exterior. If not, it can be checked for by removing an outlet or switch cover plate on an exterior wall and probing any gap between the wall material and the electrical box (it is safest to turn off the power to the outlet first). These results do not necessarily apply to the entire building as wall insulation may be installed in limited areas during remodeling projects.
The 1.5 Story Bungalow and Knee wall Attics
Many pre-WWII homes in the Portland area are built in a bungalow style where the second floor is smaller than the first floor. This results in an attic configuration that includes "knee wall attics", these are the small attic areas over the outer part of the main floor footprint. If you can access to these attic areas they present a good opportunity to install insulation in their floor (which is the ceiling of the main floor) and at the wall between the living space and the knee wall attic.
Insulated Knee wall attic floor Insulated knee wall attic wall
These homes should also be insulated at the roof peak attic area, that's the small, triangular-shaped attic above the flat ceiling of the second floor. What's tricky to insulate in these homes is the sloped ceiling area that runs from the kneewall to the flat ceiling. Getting insulation into these areas is difficult, and consideration needs to be given to maintaining adequate attic ventilation. If you live in one of these homes you should discuss this topic with a weatherization contractor.
Floor Insulation
Floor insulation is important in homes where the floor of a living space is adjacent to an un-heated area such as a crawlspace or an unheated basement. If there is a basement space that's heated and used as a living space then floor insulation is not necessary because the area above and below the floor are all conditioned living spaces and the movement of heated air between living spaces is not a loss. Homeowners may want to insulate floors for other reasons such as sound containment around a basement theatre or play room.
Older homes often do not have floor insulation. The payback on floor insulation will not generally be as quick as ceilings or walls, but it is still helpful in reducing energy use and will make a difference in comfort levels (incentives are usually available). Do note, even with floor insulation hardwood floors will still feel cold on your bare feet in the morning. In homes that do have floor insulation it is often missing or pulled down in areas as a result of repairs, animal damage (cats and raccoons love the stuff), or simply from gravity. It can be worth a fun filled trip into your crawlspace to check on the condition of any existing insulation and make repairs to damaged areas.
No floor insulation Nice floor insulation Pulled out floor insulation
Planning and Safety with Insulation
-Attic area upgrades such as new or improved wiring, sealing measures, or improved ventilation should be made before insulation is installed or added.
-Knob and tube wiring is an older wiring system present in many pre-WWII homes that is not intended to be covered with insulation as it may create a fire hazard. Any knob and tube wiring in use should be replaced or evaluated for safety by an electrician prior to adding insulation.
-Some recessed light fixtures are not meant to be covered by insulation and could overheat if they are covered. Baffles can be created around these fixtures to hold back insulation or the fixtures can be replaced with newer "IC" (insulation contact) fixtures.
-When installing insulation it can be important to maintain ventilation to parts of the structure to help prevent mold, mildew and rot fungus.
-Some insulation materials can be irritating to the skin and/or respiratory system. Some older vermiculite insulations and fiber-paper duct wraps may contain asbestos. Testing is available for these materials (web search "asbestos testing, Portland Oregon) before work begins and if they do contain asbestos special precautions need to be taken around them to avoid releasing the asbestos fibers which are a known carcinogen. A good website for more information is www.epa.gov/iaq/homes/hip-concerns.html
All these topics should be discussed with a licensed insulation contractor or electrician prior to installing insulation.
Some recessed lights shouldn't be covered Some vermiculite insulation contains asbestos