Rigid foam insulation cost
Adding rigid foam insulation to walls costs $0.90-$1.88 per square foot. This type of insulation is also commonly used on floors, ceilings and unvented roofs with low slopes. Rigid foam boards can help prevent heat flow by trapping air and gases. 
Foam board insulation
Insulating boards come in polystyrene, polyurethane, and polyisocyanurate and provide a high level of insulation for little thickness. They can be applied to both interior and exterior walls but must be covered with approved materials for fire safety. Closed cell foam insulation boards are often used to cover interior foundation walls in basement remodels. 
Insulation removal cost
If the insulation contractor needs to remove existing insulation, he may charge a separate removal and disposal fee.
The price to have insulation removed by machine can cost about $1-$1.10 per square foot.
The price to have insulation hand-removed costs about $1.35 per square foot.
Preparation can also involve fixing other damage to the attic, walls, and other spaces. In cases of water damage and mold, some insulation contractors offer mold remediation before installing the new insulation. The charge will be based on how extensive the repairs and materials needed to make the repairs.
Cleanup costs include disposal of existing insulation and other damaged building materials.Search local insulation professionals and check prices.
What's an R-value?
Insulation's resistance to heat flow, also known as thermal resistance, is measured or rated in R-value. The higher the R-value, the greater the thermal resistance at keeping heat in or out. The R-value, and not the depth of the insulation, is what determines whether your home has adequate insulation.Several factors will determine the R-value of the insulation you need, including:
- Your home's heating and cooling system 
- How many rooms or part of the home you want to insulate 
In new home construction, local building codes set the minimum R-value required for insulation. If you live in an existing or older home, going by local building codes is a good rule of thumb.
The Department of Energy also has region-specific recommended insulation R-values for your attic, walls, floors, and crawlspaces. These R-values are often higher than building code requirements. For regions in the South, the DOE recommended R-value for attic insulation ranges from R30 to R49. For northern climates, the recommended R-value for attic insulation ranges from R49 to R60. An insulation professional can help you determine what, if any, additional insulation may be needed to achieve maximum energy efficiency. When adding new insulation on top of old, insulation professionals will need to know the type of existing insulation, its related R-value, and the average depth of that material in the space. If your home's existing insulation is in good shape, new insulation can be installed on top of it to achieve the desired R-value.
Different types of insulation have different R-values. For example:
- Cellulose has an R-value of 3.2 per inch of depth 
- Fiberglass has an R-value of 2 to 2.5 per inch of depth 
Radiant barriers, however, don't have an inherent R-value. Instead, this type of reflective sheeting reduces summer heat gain by re-emitting radiant heat rather than absorbing it. It's most often used in warm climates, in conjunction with packed insulation, to reduce cooling costs.
Getting insulation cost estimates
Some insulation contractors provide cost estimates based on the project or home's square footage and age. Ask whether they're basing their recommendation on building code requirements or DOE recommendations or both. Other insulation contractors offer free in-home consultations and energy audits to determine your home's unique insulation needs. Contractors will come out and measure the condition and depth of any existing insulation. A walk through can also catch problems, such as previous insulation that wasn't installed correctly the first time. Be sure the cost estimate includes a breakdown for prep and cleanup.
Cost-saving tips
To stay within your budget, use the following money-saving tips:
- Ask for a free in-home energy audit and cost estimate. You may avoid costly surprises this way. 
- Be wary of contractors who provide estimates in inches only. Make sure your cost estimate specifies the type of insulation material, the R-value, and price per square foot. 
- Remove the old insulation yourself. Check with your local municipality about any proper disposal requirements. You can also ask your contractor whether they can dispose of it for free, or for a small fee. 
Reasons to install insulation in your home
Insulation keeps your home comfortable year-round. In the winter it keeps warm air from escaping your home, so your home stays warmer. In the summer, it keeps hot air from entering your home, so it stays cooler. It helps your heating and cooling systems work more efficiently, saving you money in energy costs.
The main reasons for new home insulation include:
- Making your home more energy efficient. The attic is the most common space insulation is needed. If you live in an older home, you may need insulation in the wall cavities—the space between the exterior shell and interior perimeter drywall. Spaces between floors and crawl spaces may also benefit from insulation. 
- Finishing a space. If you want to create living space from an unfinished basement, you'll need to insulate those walls, too. 
- Soundproofing spaces. Home insulation can also keep you comfortable in other ways. It can be used between drywall and floors to soundproof rooms, such as media rooms. 
- Preventing roof ice dams. Ice dams occur in climates that get significant snowfall and freezing temperatures. As snow on your home's roof melts, it should flow down your gutters. Inadequate insulation can cause hot and cold spots that cause melting water to clog, forming a dam that pushes water into your attic or ceiling or down your walls. Icicles along your gutters are a telltale sign that your ceiling or attic may need more insulation. 
- Problems with existing insulation. You might need new insulation because of unrelated water damage or a pest problem, such as a squirrel or raccoon nest. Old home insulation that's deteriorated may no longer be effective. Deteriorated cellulose fill may also cause fine dust that can leak and disperse throughout your home. 
Find insulation contractors near you
Make your home more energy-efficient and comfortable by installing (or upgrading) your insulation. Use Thumbtack to start searching and comparing insulation contractors in your area.