According to the US Department of Energy, a completed basement may save households up to $390 in annual electrical expenses. These savings increase in homes where electricity is used for heating.
The advantages of completing basements include increased comfort, improved indoor air quality, energy savings, and moisture management.
While it takes time to see a return on investment, you’ll find that insulation improvements pay off faster than window replacements. This brings us to how to insulate a basement with minimal sweat and tears.
Keep on reading for our full breakdown on everything you need to know about basement insulation.
How to Insulate a Basement 101: Preparing Your Basement
Let’s start with the basics.
Moisture is the most essential factor to consider when insulating your basement. Perform a simple test using plastic sheets and duct tape to verify there is no moisture leaking through the walls.
Wait for at least 48 hours after applying an impermeable duct tape border to a small piece of plastic sheeting on a plain concrete wall. After a period of time, look for condensation on the inside and outside of the plastic sheet to determine whether water has seeped through.
The tie rods buried in the concrete (which were previously used to maintain the form of your home’s foundation while it was being poured) should be sealed properly. Make sure you’re using a center punch with a masonry hammer to push the tie rods into the foundation wall. Mix up some hydraulic cement to plug the tie rod holes.
It’s best to use this cement in small amounts since it builds up so quickly. When properly mixed, the cement should resemble peanut butter in consistency.
The Best Types of Insulation for Your Basement
Before we get into the specifics of how to build an enclosed basement system for moisture management, let’s take a quick look at some of the most common insulating materials and techniques for various basement types.
Aside from foam board and spray polyurethane foam (SPF), there are hundreds of other kinds of insulation materials to choose from. In certain cases, it may be advantageous to utilize a combination of systems.
Let’s explore the five insulating situations listed below.
Interior walls may be insulated using rigid polyiso or extruded polystyrene (XPS) foam board, with SPF sprayed to air seal and insulate the rim joists.
Taped foam board is a less expensive alternative. A “hybrid” mix of taped foam board and batt insulation is another option.
Exterior insulation should ideally be placed prior to backfilling walls. If permanent features such as walkways, driveways, or patios make digging the basement wall prohibitively expensive, foam board should be installed along the foundation’s outer wall for many feet.
The board should then extend 3 to 5 feet from the vertical walls, depending on the size of the space. Also, this is how frost-protected shallow foundations are constructed.
To air seal and insulate the basement walls, a mix of foam board and spray foam, or taped foam board, is suggested, similar to monolithic concrete.
Also, you’ll want to make sure that you’ve got no furniture or items that can get stained before starting your project.
This is also known as a double brick wall with rubble fill.
The simplest method to achieve internal insulation and air sealing is to use closed-cell SPF.
Laid-up Stone Foundation
We propose using the same method as the double brick, rubble-filled wall, whereas other professionals might suggest waterproofing and insulating the floor with a vapor-retarding membrane installed throughout.
Spray foam may achieve several basement finishing objectives at once. It may be used as an air, water, moisture, and temperature control surface for the wall in certain applications.
It should not, however, be exposed when used in large amounts. A thermal/fire barrier should be installed to safeguard it.
Now, keep in mind that if your heart is set on insulating your basement, you’ll want to consider insulating your loft at the same time. If you’re not sure whether it’ll be worth the effort, you can check out these benefits.
Basement Insulation: A Step-by-Step Breakdown
Start by applying a foam board adhesive to the back of a polystyrene insulation panel once the cement has set, then push the panel to the wall. Ensure that your glue is solvent-free, since solvents may eat away at foam insulation. The remaining panels should be adhered to and applied.
Then, you’ll make a wood grid to keep the drywall in place. To begin, measure three inches from the top and bottom of the room’s floor and ceiling.
Draw five identical horizontal chalk lines all across polystyrene panels using these dimensions. This will serve as a blueprint for constructing the grid. Then, using a 1×3 spruce board, trace the chalk lines you’ve drawn.
Next, drill 5-inch holes through the 1×3 and into the concrete barrier using a hammer jackhammer and a 3/16-inch masonry bit. The 1x3s will be secured using 4-inch-long spring spikes, which resemble nails but have no point and a kink at the tip. This works as a spring, straightening out the spike and anchoring it to the concrete wall.
Now, you’re ready to screw vertical 1x3s to horizontal 1x3s using 1 5/8-inch drywall screws after the horizontal boards are in place. This will leave a vertical and horizontal space in which to place any future electrical wiring. Finish putting the vertical boards after spacing the horizontal 1x3s 16 inches on center.
After you’ve installed your grid, it’s time to put up your drywall. Greenboard that can withstand dampness is ideal for basements.
Insulation for Winter: Clear and Simple
If you’re not used to finishing your own home DIY projects, then the idea of insulating your own basement can seem overwhelming.
Hopefully, our guide has shed some light on how to insulate a basement in simple and easy steps.
And, if you liked reading this article, then you’ll want to check out our other tips and tricks. All of them will be available to you in our home improvement section.