Attic Wall Crawlspace InsulationMore Information About Insulation

No matter how old your house is, it probably has some insulation. Insulation of one kind or another has been around for hundreds of years, but it wasn’t until the 1960s that building codes began requiring insulation in attics, walls and floors. Today, new homes are fully insulated during construction, but older homes can be retrofitted with insulation, as well. How that is done, and what materials and techniques are used, varies from one part of the house to the other, and may depend on the design and construction details of the house.


If you’ve been in your attic a few times, you know it can be a very uncomfortable place: cold in winter and hot in summer. The purpose of attic insulation is to slow the transfer of heat through your ceilings, which helps keep your house comfortable and energy efficient year-round.

New homes are required by code to have up to sixteen inches of insulation in their attics. Older homes usually have lesser amounts, and a few still have no attic insulation at all. Fortunately, installers can add insulation to most attics to the same levels as in new homes. The insulation, usually tufts of fiberglass or cellulose, is “blown” over the attic floor and is called “loose-fill” insulation. If there is already some insulation in the attic, loose-fill insulation can be blown over the top of it, provided the old insulation is good condition and not contaminated by mold, rodent droppings or other hazardous substances. If necessary, contaminated insulation can be vacuumed out and the attic cleaned and repaired before new insulation is added.


While older homes often have some attic insulation, their walls usually have none. This is because, unlike attics, the inside of a wall is covered on all sides, which formerly made them difficult to insulate. But just as insulation is now blown into attics, it can also be blown into a wall through holes drilled for that purpose. Because this insulation, which may be fiberglass or cellulose, is tightly compacted inside the wall, it is called “dense pack insulation.”

Note: Unlike many contractors, Vesta never drills holes through siding to blow insulation into walls. Instead, we remove a few pieces of siding prior to drilling the holes, then reinstall the siding after the work is completed. This maintains the beauty and integrity of the siding.


A floor in your home only needs to be insulated if it serves as the boundary between indoors and outdoors. This includes floors over crawlspaces, unconditioned basements, and garages, as well as floors that overhang outdoor space. In crawlspaces and basements, floors are usually insulated with fiberglass batts installed between the floor joists. In garages and other areas with finish ceiling materials (wallboard), floors can be insulated with blown insulation, similarly to what is done with walls. Floors that overhang exterior spaces can be insulated with fiberglass, rigid insulation, or spray foam insulation, and then sealed and covered from below.


If any of your home’s heating ducts run through unconditioned spaces, such as a crawlspace or garage, those ducts should be insulated. Ducts are usually insulated with fiberglass blankets wrapped around the ducts. Before insulating those ducts, however, they should first be sealed with duct mastic, which forms an airtight, flexible seal at all connections. Sealing your ducts not improves the performance of your heating system, but prevents contaminated air from the crawlspace, garage or attic from getting into the ducts and being distributed throughout the house.

Planning and Preparing for Insulation

Your home is not just a collection of isolated parts, but a system in which the performance of one part affects the performance of other parts. The amount of insulation, for example, can affect the operation of the heating system. Uncontrolled air movement through the building exterior affects the performance of the insulation itself. For this reason, it is important to take steps prior to installing insulation that will maximize its performance.

Before adding insulation to an attic (and anywhere else), necessary repairs should be completed, such as repairing roof leaks and damage caused by insects or rodents. Upgrades to the electrical, plumbing and duct systems should also be considered, as they will be more difficult to do after insulation is installed. And finally, the floor, wall or ceiling being insulated should be air sealed to reduce leakage, which allows heated air to escape a house and cold air to enter. Typical air leaks include holes cut in the ceiling for recessed lights and bath fans, but may include large holes from the original construction that cannot be seen from inside the house. The Vesta SWAT Team is designed to address these problems in order of importance, leaving you correctly prepped for insulation.