How to Insulate a Basement | This Old House

This Old House general contractor Tom Silva shows how to warm up a chilly concrete wall. (See below for a shopping list and tools.)

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Tom helped a homeowner prepare the bare concrete walls in his basement for wallboard. The homeowner wanted to convert his unfinished basement into living space. The first step was to plug the holes in the concrete walls that might let water seep in from outside. To do this, Tom mixed up some hydraulic cement and forced it into the holes. Hydraulic cement expands as it cures, forming a watertight seal. Next, Tom used 2-inch thick foam insulating board to insulate the basement. He applied it to the concrete walls using a special foamboard adhesive. With the foam insulation installed, Tom fastened a wooden "grid" of 1x3 spruce boards over the insulation using masonry "spring spikes." This grid allows wallboard to be fastened with regular drywall screws, and gives an electrician a place to snake wires and install electric boxes for outlets and light switches.

Shopping List for How to Insulate a Basement:
plant mister [amzn.to/4ggeiXu]
tie rods [amzn.to/40DofID]
hydraulic cement [amzn.to/42TLXDt]
2-inch-thick rigid polystyrene [amzn.to/3EeA7Jw]
foam board adhesive [amzn.to/3EtDCMf]
1x3 spruce [amzn.to/40SoWzb]
4-inch-long spring spike [amzn.to/4hiHlLa]
1 5/8-inch drywall screws [amzn.to/4gf5Do8]

Tools for How to Insulate a Basement:
masonry hammer [amzn.to/2WArsqf]
center punch [amzn.to/3PZnHYK]
margin trowel [amzn.to/4hV1hUD]
caulking gun [amzn.to/3EfevN7]
chalk reel [amzn.to/4hmPP43]
hammer drill [amzn.to/4jEUeB6]
3/16-inch masonry bit [amzn.to/4jHoTh9]
drill/driver [amzn.to/4aDIyKC]

Tom used Quikrete [quikrete.com/] hydraulic cement to plug the holes in the concrete foundation
Tom used two-inch thick rigid foam insulation on the walls manufactured by Owens Corning Insulation [owenscorning.com/en-us]
Tom used masonry "spring spikes" to attach the 1x3 lumber to the concrete wall manufactured by DeWalt [anchors.dewalt.com/anchors/].


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Homeowners have a virtual truckload of questions for us on smaller projects, and we're ready to answer. Ask This Old House solves the steady stream of home improvement problems faced by our viewers—and we make house calls! Ask This Old House features some familiar faces from This Old House, including Kevin O'Connor, general contractor Tom Silva, plumbing and heating expert Richard Trethewey, and landscape contractor Roger Cook.
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How to Insulate a Basement | This Old House
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