Because a large volume of indoor heat is lost through the ceiling, the attic floor above is considered the most important area in the house to insulate for winter comfort and efficiency.
Attic. Arguably the most important space in the home to insulate is the attic. This is primarily because heat naturally rises, which means that the attic will hold a lot of the heat generated in the home.
In addition to walls and attics, insulation should be installed in ceilings with unheated spaces, basement walls, floors above vented crawl spaces, cathedral ceilings, floors over unheated garages or porches, knee walls, and in between interior walls—especially bathrooms—as well as ceilings and floors.
If you were on a very skinny budget and had to make a choice, you would insulate your ceiling first. Installing ceiling insulation can save around 35% on heating and cooling energy. Compare this to insulating your walls. Insulating your walls saves around 15% on heating and cooling energy.
Do not cover any ventilation with fiberglass insulation and do not wrap wiring with insulation. Insulation can be flammable. Don't allow gaps in your attic. If you do find small gaps, use spray foam or seal with caulk.
In most cases, interior walls are not insulated during construction. Unlike exterior walls, which must meet local and state codes for insulation, interior wall insulation is rarely required. This is because interior insulation has much less impact on your home's energy efficiency – but it can still play a role.
Absolutely. Wall insulation prevents your home from heating up in summer and keeps your home warmer in winter. Around 15-20% of a home's heat loss and gain occurs through the walls.
Better: insulate the sloped ceiling
It's usually easier and more effective to insulate the sloped ceiling rather than the kneewall. In a traditional story-and-a-half Cape, the insulation should extend from the rafter bird's mouths to somewhere above the flat ceiling above the second floor.
The walls, floors and ceilings of your home should feel warm and dry to the touch. When drywall and panelling inside a home feels damp or cold, that's a clear sign there's not enough insulation. Alternatively, when touching an exterior wall, it should feel cold because insulation is keeping warm air inside a home.
As a general rule, insulation should be replaced or retrofitted every 15 to 20 years. However, it may need replacing or retrofitting sooner depending on the type of insulation installed, the R rating of the original insulation, compression and movement over time, and whether any damage has occurred.
If you were to insulate your main walls internally, any heat within the walls (from the sun heating them) wouldn't enter the property as the internal insulation would stop it getting through. On the other hand, if you install external insulation, you'll stop the sun being able to heat the walls in the first place.
The answer is, you should do both. The average home needs to be insulated high, middle, and low. All three areas are important. This means you need to have attic insulation, wall insulation, and basement or crawlspace insulation to produce the greatest level of comfort and energy.
An insulating material's resistance to conductive heat flow is measured or rated in terms of its thermal resistance or R-value -- the higher the R-value, the greater the insulating effectiveness. The R-value depends on the type of insulation, its thickness, and its density.
Thermal Benefits
Heat naturally travels from places of high heat energy to places of low heat energy, making it hard to keep your home cool in summer and warm in winter. The best way to prevent unwanted heat loss and gain is to use insulation throughout the home, including between floors.
Generally speaking, you only need to insulate the ground floor. If you're on an upper floor, you don't usually need to insulate your floor space. However, you should consider insulating any floors that are above unheated spaces such as garages, as you could be losing a lot of heat through those.
Here's where you should insulate in your garage: Your garage ceiling—if it's attached to a room in the house or an attic that extends to other parts of your house. Any garage walls attached to interior rooms in your house—other than the ceiling, this is where you get the most improvement in cutting energy waste.
Too Much of a Good Thing
There comes a point where too much insulation starts to have a negative effect — financially, environmentally, and in terms of the longevity of your home. So yes, it is possible to over-insulate your house.
Even in smaller households, certain rooms can benefit from better noise control. Your home office, game room, kid's playroom, and even the bathroom are good places to consider adding interior insulation.
In fact, adding too much insulation to your walls can lead to problems such as poor ventilation, mould growth, and condensation. This is because thicker insulation can block airflow and trap moisture, leading to indoor air quality issues and even structural damage.
Proper insulation will help keep your bathrooms a comfortable temperature year-round. Bathroom projects need special consideration because of the humidity and moisture that bathrooms generate. When moisture becomes trapped in walls, mold and mildew can grow, damaging your home and presenting a potential health danger.
Without insulation, heat from your home can escape through the walls, making it difficult to maintain a comfortable temperature indoors. This heat loss can also lead to higher energy bills and wasted resources.