Ways to Insulate Existing Walls
- Use rigid board insulation when insulating existing solid walls such as bricks.Architectural joint - old stone wall and new brick wall image by astoria from Fotolia.com
It may seem easier to tear down walls and start with a clean slate to insulate an existing home properly. However, some older homes may have walls such as bricks or finished woodwork that are difficult to remove and costly to repair and replace if you want to tear them down for insulation. Fortunately, other options are available to let you insulate without tearing down existing walls. - Take advantage of any open cavity, which is an ideal spot to put in insulation. One of the methods you can use to insulate existing walls through an open cavity is through blown-in insulation. Performing this type of insulation on your own may save you money; however, the process takes time to learn. Fiberglass, cellulose and foam are the three options for blown-in insulation. Find blower equipment at your local rental yard to cut the cost down.
Fiberglass-based blow-in insulation is ideal for attics and hard-to-reach areas. Properly applied, blown-in fiberglass insulates well. Avoid a "fluffed up" or overblown result by placing enough material to reach the desired depth as well as using proper rated R-value insulation by following the manufacturer's recommendations for depth and density.
Cellulose insulation consists of up to 85 percent recycled newsprint with the remaining 15 percent consisting of a mixture of borate and ammonium sulfate that acts as mold prevention, is fire retardant and deters rodents and insects. Made of small particles, lose cellulose is ideal for filling empty spots and corners. The preferred method for existing wall is the dry spray method; however, the spray takes a long time to settle and is a health hazard. To avoid inhaling the particles, wear a dust mask and eye goggles.
Cementitious foam, which is a product from seawater, is an effective material for blowing into existing walls because it can work its way around any obstacle. Unlike the other two choices, foam does not leave any void spots and does not produce dust; therefore, it is a safer method during installation. - Pouring, spraying and injecting liquid foam into existing walls can fill even the smallest empty space. Liquid foam, which includes cementitious, phenolic, polyisocyanurate and polyurethane, provides twice the R-value per inch of traditional batt insulation. Use small spray containers when working on smaller projects or pressure-sprayed methods (foamed-in-place) for larger projects. The liquid foam expands and hardens once the mixture of liquid foam and foaming agent cures. Liquid foam can fill and seal odd spaces as well as conform to the shape of the cavity.
- If the existing walls do not have cavities, such as those made of poured concrete, bricks and concrete blocks, adding a layer of insulation on top of the existing walls is your best approach. Put up wooden studs, and fill them with fiberglass batting or rigid board insulation. You may opt to glue the rigid boards on top of the existing walls. Covering the insulation with a polyethylene plastic prior to adding sheetrock panels on top prevents vapor or moisture buildup. For existing exterior walls, install rigid board insulation on top, and add new siding or stucco on top.
