If you haven’t installed crawl space insulation in your house yet, you need to do so as soon as possible. The loss of heat or cold resulting from the lack of insulation can cause a substantial increase in your energy bills. Moisture can also enter the crawl space, resulting in rot and costing you more in maintenance bills in the long-run.  Now that I’ve got your attention, here are some tips on how to install your crawl space insulation.

How you install crawl space insulation depends on whether or not your space is ventilated or unventilated. If your crawl space is unventilated, then it will be easier to insulate. You only have to apply crawl space insulation on the foundation’s walls rather than the sub-floor. You will need Batt insulation with an R-factor of 10. Cut lengths of the insulation material long enough to extend from the mudsill (the board on top of the wall) all the way down to around two feet onto the floor. Secure the material with 2 by 2 cleats, then drive nails through the cleats into the mudsill. Hold the insulation along the bottom of the wall in place by placing some bricks or a length of 2 by 4 lumber on top of it. Also, cut small pieces of insulation to insulate the joists.

Installing crawl space insulation is harder if your crawl space is ventilated. First you have to prepare the space by ensuring that all holes in the floor above are sealed to stop air from blowing into the house. Apart from applying crawl space insulation to the walls, you also need to insulate between the floor joists using rolled fiberglass. Ensure that the insulation is firmly in place by using mechanical fasteners.

When installing crawl space insulation, you should also keep moisture control measures in mind. Face the insulation with a vapor barrier. Although the vapor barrier is usually placed upward, in areas of the country with mild winters and hot summers the vapor barrier should face downward. You also need to install moisture retarding material (such as polyethylene vapor retarder) on the dirt floor and make sure it is carefully taped and sealed. Cover it with a fine layer of sand or concrete to prevent it from damage, but avoid materials that could pierce it such as crushed gravel. You also need to place crawl space insulation on the air ducts. Don’t forget to close the vents after installing insulation to ensure that the space stays dry. And take pest control measures as the insulation may be damaged by rats and other vermin.

You may also want to consider friction-fit Batts if you are installing crawl space insulation in a ventilated area. This type of insulation has metal rods as thick as the metal used in hangers (called ‘lightning rods’) fixed inside the fiberglass. These lightning rods stick out a couple of inches longer than the inside joist spaces to hold the insulation up inside the floor joists. Using friction-fit Batts makes it easier to place crawl space insulation on a floor from below.