How much insulation is enough?

How much insulation is enough? Insulation requirements vary with the area of your home. The attic insulation requirement by the International Residential Code is a minimum of R-38. This means that the "blown-in" level of insulation in your attic space should be approximately 16". I added some insulation to my attic space by blowing 10 bags of insulation with a machine from my local lumber yard. The use of the machine was free with the purchase of the insulation. The insulation cost was approximately $55 per bag. Insulation in your walls should be a minimum of R-19 as required by the IRC. Older homes will not meet the minimum requirements. Most of the older homes, depending when it was built, will vary with the thickness of the wall. A wall with 2 x 4 construction will be R-11 to R-13. Bringing older homes up to code compliance standards can be challenging. Most older homes are brought up to these standards by adding insulation to the exterior of the walls with insulation board under new siding, for example. Other areas of concern are the rim joist area. This is the area above your foundation wall between the top of the foundation wall and the bottom of the first floor. This area i s a major heat loss area and should be addressed bu adding insulation. This can be done by using R-19 batt type insulation, plastic foam insulation (minimum 2" thick), or faced style insulation with a paper face or foil face type. Whatever your choice, the rim joist area is a major contributor to higher heat bills. Whatever your choice for adding insulation to your home, you should first consult a professional insulation contractor. Make sure your contractor is reputable, licensed and trustworthy. Any insulation improvements are going to reduce your energy bills and saving money is what this is all about. Insulation upgrades usually pay for themselves in a very short time. Building Codes are minimum standards. They are set as guidelines for builders and independent contractors. Ask your insulation contractor what he thinks the minimum amount of insulation should be. Compare his answer with the minimum code requirements as stated above and you will know what to do from there. GOOD LUCK and keep warm this winter. -Inspector Tom