How to Cut Fiberglass Roofing Shingles

What You'll Need
Fiberglass shingles
Measuring tape
Marker pen or chalk
Hook bladed utility knife

Fiberglass is a particularly popular material for roofing in the United States and fiberglass roofing is durable and requires minimal maintenance. It is also cost effective and is often a preferred choice for gambrel roofs. Fiberglass roofing shingles are similar to asphalt roofing in terms of appearance though they are not quite as common. Cutting fiberglass shingles requires a certain technique and a choice of specialized tools for the job. It can be an especially frustrating task. The job is often done using a special utility knife though it can also be done using shears specially designed for cutting fiberglass and similar materials. 

Step 1 – Take the Measurements

To install shingles on the sides of the roof, you will likely need to cut them. They will also need to be cut where they have to make way of obstructions in the roof such as chimneys or flues. Using the tape measure, take the measurements that you need to cut the shingle to and mark them on the back of the shingle using chalk or a marker pen. It is always a good idea to double check your measurements to be sure that they are as accurate as possible lest you risk wasting perfectly good tiles by cutting them incorrectly. You can also mark the cut lines using the hook bladed knife itself. Another way of measuring the shingle is by setting it on the roof where you are going to install it and using that as a reference.

Step 2 – Cut the Fiberglass Shingle

You can either cut the shingles as you need them or do them all at once using a chalk reference line drawn onto the roof itself. This is a great deal more complicated, however and the regular method is generally more recommendable. To cut the shingle, place the speed square to guide the knife along. Guide the knife down the first half of the shingle, cutting it from the back of it. Flip the square to the other side of the shingle and cut from the opposite direction so that both of the cut lines line up. To break the shingle apart, fold it over. Fold it back and forth slightly so that a crease forms allowing to you break the shingle apart. Be careful not to tear the shingle when you do this.

Step 3 – Other Methods of Cutting Asphalt Shingles

You can also use a chop saw to cut asphalt shingles though this needs to be done with an especially clean blade otherwise it is more likely that the tar will melt on the blade due to heat generated by friction. If you use the right technique using the chop saw method, you can get the job done much faster. Before you begin, make sure that you clean the blade using some heavy duty household cleaning agents.