How to Insulate a Vented Crawl Space

Older homes often have ventilated crawl spaces beneath them (you can tell if your crawl space is ventilated because there will be a number of vents in the side wall specifically for ventilation). This ventilation is necessary to make sure moisture doesn't become a problem in the confined space. However, with a ventilated crawl space (particularly in colder climates), drafts and cold floors in the living space are a common occurrence. If you have a ventilated crawl space--you don't need to put up with that discomfort. By properly insulating your crawl space you can make your home more comfortable--and even save yourself some money on your home heating bills over time. Here's how to insulate your ventilated crawl space.

Things You'll Need

• Faced fiberglass insulation (bats or rolls)
• Utility knife
• Straight edge
• Tape measure
• Sheets of 6 or 8 mil plastic
• Sealing tape
•  Stapler and staples
•  Chicken wire

Instructions

1. Start insulating your crawl space by installing insulation underneath the floor, between the floor joists.

2. Measure the length required for a piece of insulation to fit in between two floor joists from wall to wall.

3. Cut the insulation to length by marking the proper length, then putting the straight edge at the mark on top of the insulation. Press down on the straight edge and cut along it with your utility knife.

4. Install the insulation with the facing side pointed towards the underside of the floor (not down into the crawl space). Floor joists are commonly 16 inches or 24 inches apart and fiberglass insulation is available in these widths. Friction will hold the insulation in place while you work.

5. Continue to cut and install insulation between the floor joists until the entire "ceiling" is covered.

6. After insulating between all the floor joists, staple chicken wire onto the bottom of the floor joists to hold the insulation in place. This will ensure that the insulation stays in place over time and also make it difficult for any animals that might get into your crawl space to use the insulation as nesting material.

7. Wrap any exposed heating ducts or plumbing pipes with insulation to prevent heat loss or a frozen pipe.

8. If you have a dirt floor, cover the floor with sheets of 6 or 8 mil plastic. Overlap the edges by about 10 inches and use sealing tape to seal along the seams. This will help prevent moisture from getting into your crawl space.

Tips & Warnings

• Refer to my eHow article: "How to Insulate an Unventilated Crawl Space."

• You can obviously use other types of insulation (reflective, foam boards); however, rolled fiberglass is easy to work with and can be cut to the proper lengths.

• You should cover the plastic vapor barrier on the floor with sand or bricks to hold it in place.

• Even after your crawl space is insulated, if you live in cold climate, try closing your vents in the winter. Blocking out the cold air will keep your living area more comfortable.

• When you're working with fiberglass insulation, always wear gloves, eye protection, a long-sleeved shirt and a dust mask.