Features

• Foam insulation is available as an open-cell or closed-cell product. Depending on the product, closed-cell polyurethane foam, also referred to as high-density foam, expands about six to 30 times its original state. It cures in a manner that is firm and rigid. The rigidity of closed-cell insulation helps to strengthen the structure. Closed-cell foam does not allow water or air to penetrate.
  
  Open-cell polyurethane, also called low-density foam, expands as much as 120 times its liquid form. Low-density foam cures into a soft pillow-like form, which is not as strong as closed-cell insulation. Open-cell polyurethane insulation can be infiltrated by water and air.
  
  Polyurethane foam adheres to structural materials, unlike fiberglass or loose-fill insulation, and will not settle of sag over time. Closed-cell polyurethane foam has a 7.0 R-value per inch. In contrast, fiberglass insulation has an R-value of 3.5 per inch. In addition, closed-cell polyurethane foam insulation does not require you to install an air barrier or vapor retarder.
  
  Foam insulation can protect against insects and rodent infiltration by filling wall cavities.
  
  

Installation Guidelines

• Most DIY polyurethane foam insulation kits come with everything you need for a high-quality installation. The kits include a container of foam and a hose with a spray gun attachment, and nozzles if necessary. Although the product is safe for the most part, you should wear gloves and a respirator when working with polyurethane foam. It also is very adhesive and hard to clean, so wear old clothing.
  
  The application process is straightforward. Make sure that the container is at the maker's suggested temperature to ensure that the liquefied material flows, expands and cures properly. Position yourself about 18 to 24 inches away from the cavity. Use a back-and-forth motion, such as you would if you were spray painting, and cover the area.
  
  If interior walls or ceilings are in place, cut three small holes about three feet apart from the bottom, middle and top. Starting working at the bottom, and plug the holes as you move up to keep the foam from leaking out of the walls. Do not plug the top hole. Use a slow-rise formula, which expands slowly and will not push drywall out of place.
  
  

Where to Use It

• Use polyurethane foam insulation just about any place you would use other insulation, including walls, ceilings, floors, attics and crawlspaces. Verify that the local building codes allow foam insulation.
  
  If you plan on using closed-cell polyurethane foam insulation, find out what the local building codes are regarding the installation of closed-cell foam between floor joists and rafters. In most homes, the attics are the primary avenues for allowing moisture to escape. Because closed-cell foam insulation is not permeable, air or water vapors may get trapped, which could lead to rot, mildew and mold. Use open-celled foam for such areas.