Summer DIY Project: Fill the Cracks

— Written By Trudy Pickett and last updated by

Gaps, cracks and holes in your home can result in serious loss of heat through the winter, so try filling them in as a home improvement project this summer. High-quality caulk is available at your hardware store for under $3.00. Add a pack of foam sealants for under $5.00 and a few packages of weather stripping for less than $2.00 each and you have the tools necessary to get this job done! The experts say that the average home can have combined cracks and gaps amounting to sixteen square feet of space!

There are two types of expanding foam sealant: polyurethane products and latex-based products. Both types fill gaps and holes that are too large to pack with caulking. Polyurethane foam cures to a rigid but porous texture, and can be sculpted while wet to a suitable shape. Latex foam cures to a spongy non-sculptable texture, but while it is still setting up it can be tooled, shaped or molded, giving you lots of texturing options. Both latex and polyurethane foams stick to almost anything including wood, aluminum, masonry, galvanized steel, plastic, rubber, drywall, glass and, based on experience, SKIN. Be careful where you put it!

More great things about expanding foam sealant:

  • Foam acts as a form-fitting barrier to the elements, and has no nutritional value so it doesn’t attract insects or rodents.
  • Foam doesn’t support the growth of mold or fungus in damp conditions.
  • It doesn’t have an offensive odor as you’re using it, or after it has cured.
  • Many brands of foam are free of volatile organic compounds that pollute the environment. Read the label.
  • Foam efficiently seals air leaks that compromise the energy-efficiency of your home.
  • Foam sets up quickly, fills large voids, deadens sound, is airtight and water resistant and conforms to any shape as it expands.
  • Foam can (and should) be painted after it’s fully cured to protect it from UV light, which causes discoloration and deterioration.

If you haven’t used expanding foam before, go with a low-expansion variety. (The label will indicate whether it’s high- or low-expansion.) If you choose a high-expansion foam, use it with an extremely subtle touch. It expands 200-300 percent over a couple of hours. In other words, you only need to squirt in 35 -50% of what you think you need. If you overdo it, you’ll have unsightly glops of uncured foam spilling out of crevices, not what you want. It cleans up with acetone but not easily, so take care with applying expansion foam. Wear gloves and eye protection when applying expansion foam. You’ll be glad you did!

Resource: University of Nebraska–Lincoln Extension

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