How to Cut Fiberglass Insulation

Fiberglass insulation is one of the most popular ways to keep your home warm. Since it's inexpensive, easy to find, and very dense, you can't go wrong with padding your walls. However, it's very squishy, so you might be a little confused about how to cut it. This is a very abrasive material that requires a sharp blade and some safety gear such as a dust mask and glasses. However, with some basic techniques, you can cut insulation board safely and efficiently.

1. Measuring insulating materials

   Choose a piece of plywood that is at least as wide as the fiberglass board. Place it on a flat surface so there is enough room to spread out the fiberglass. The plywood doesn't have to be too big, just make sure it fits underneath the part you're cutting. [
   

   Choose a sturdy piece of material, such as a piece of old plywood

   You can put plywood on the floor for protection.

   Avoid cutting bare surfaces such as concrete.

2. Wear cut-resistant gloves and other protective clothing. Fiberglass insulation is skin irritating, wear long pants and a long-sleeved shirt. Then, put on gloves, and some also wear disposable coveralls to prevent the insulation from spreading onto their clothing.

   If part of your skin is exposed, apply some baby powder on it. The powder prevents glass shards in the insulation from sticking to the skin.

3. Wear a dust mask and safety glasses for protection. A regular N95 cloth dust mask will do just fine, if the mask you're using doesn't cover your eyes, buy separate glasses. Wear safety gear whenever cutting insulation.

   The dust released by the insulation is harmful and can aggravate breathing problems such as asthma.

   If you can, work outside so that dust doesn't settle in your home.

4. Unroll the insulating paper face down. Fiberglass insulation is rolled into a roll. Place the roll over the edge of the plywood. Then, push it through the plywood. Spread out just enough to make the cut you want to make.

   Most insulation has a paper backing on one side. It's usually easier to cut the paper last, and the backing keeps the insulation clean when you unroll it.

5. Use a tape measure to determine where you will cut the insulation. Start by measuring where you plan to install the insulation. Plan to cut the insulation 1 inch (2.5 cm) larger than the insulation on all sides. Because fiberglass insulation is flexible, it can be tucked into tight places. The extra length will help it stay in place.

6. Mark the measurements on the insulator with a permanent marker. Use a tape measure to transfer the measurement to the insulator. Measure along both sides of the insulation, making small marks to indicate where you plan to cut.

   If you roughly cut the insulation to approximate size, you don't need to take any additional measurements. If your goal is a precise cut, you can use a piece of sawdust to make a straight cut in most cases.