How to Cut Drywall with a Utility Knife
Here are some useful tips for working with drywall
Drywall is one of the most common construction materials, which is nevertheless very fragile. It is used for covering ceilings and walls, but also to create a variety of decorative elements in home interiors. However, sloppy cutting leads to overconsumption of drywall and unnecessary costs. But you should not get upset, because correctly cutting drywall with your own hands is not difficult. It is just to follow instructions. Let's start with the drywall structure and which knives that are suitable for cutting drywall.
The Structure of Drywall
Get familiar with how drywall is structured to understand the principles of cutting. The inner layer of the sheet is gypsum with fillers added. The two outer layers are formed by cardboard, which gives the material its strength. Gypsum is brittle, so without cardboard, the sheets will break and crumble at the slightest mechanical impact.
Gypsum plasterboard comes in three varieties: regular, water-resistant and fire-resistant. The water-resistant variety is used for cladding walls, ceilings and creating decorative structures in wet areas. Fireproof gypsum board is needed for constructions that are planned to be placed near a fireplace, stove and other sources of heat. Regular - for all other cases.
What Knife is Suitable for Cutting Drywall
The utility knife or dolphin knife with trapezoid utility blade is designed specifically for working with drywall. It has an ergonomic handle for optimal transfer of force from your hand to the material. Trapezoid blades have good rigidity, and don't bend under pressure. This type of blades are designed for cutting drywall.
How to Cut Gypsum Board with a Utility Knife
Gypsum plasterboard is very flexible, so it must be placed on a flat and stable surface. A tape measure and a pencil, ruler, etc. are used for marking the cutting line.
Take measurements and apply the marks. Use a simple pencil, because marks left by a marker or pen will not be covered by putty. Mark the lines on both sides.
Adjust the length of the knife so that the blade is shorter than the thickness of the sheet. Then, place the blade close to the ruler on the line and make the cut along the entire length of the guide. The pressure on the blade should be light so that only the outer layer of the cardboard is cut.
Then the sheet of drywall should be moved closer to the edge of the base on which it lies, and gently tapped. As a result of tapping, the gypsum layer along the cut line will lose its integrity. Next, it is necessary to grasp the cut off part of the sheet and bend it sharply downward, so that the plaster layer will break exactly along the line.
It remains to take a knife, bend the sheet along the line of the cut and finally divide it into two parts. It will not be difficult at all, since the halves will be held together by only one layer of cardboard.
After the sheet is divided, the edges of the cuts can be deburred with a special or conventional planer, as it can leave sloppy nicks that will be an obstacle when the sheets are docked on the wall. Chamfering should be done without strong pressure, as the material may start to crumble.
Watch this video where we demonstrate how to cut drywall in a straight line with the Sollex 2000 Universal Utility Dolphin Knife
Here are some more useful tips for working with drywall that you will definitely need:
- Be sure to use a knife with a sharp blade.
- The work is performed on a dry surface - if the drywall has absorbed moisture, you will not be able to cut it properly. Cutting is usually carried out on the back side (the one that will be installed to the wall), so you can hide the deficiencies formed during the work.
- If you need to cover a large area with drywall, it is best to use 3.6 meters instead of the standard 2.5 meters. This way you will save time and the material itself.
- Make a detailed plan for using drywall boards so that you know exactly where the material will need to be cut.
- If you are going to mount drywall on the ceiling and on the walls, you should start with the ceiling.
- It is best to attach as many whole boards as possible. This way the cladding process will go faster, and the cost of materials will be less.
- If you need to cut the material in a complex path, first cut the length and then the width.
- Larger sheets are better cut with the wall at a slight angle. And small sheets can be cut on the floor.
Is a Utility Knife and a Drywall Knife the Same Thing?
Yes, we would say that utility knives are almost always suitable for cutting drywall, especially those with trapezoidal blades. Trapezoidal blades are thicker and more durable and usually have double grinded blades, which makes them also very sharp. You can find a large selection of trapezoidal blades in our "Utility Blades" category.
Can I Use a Snap-off Knife to Cut Drywall?
We would advise avoiding the use of knives with snap-off blades for cutting drywall and tough materials, as with a lot of pressure on the blade, a piece of blade can break off and injure the user. But if you only have a snap-off knife, then use it for cutting hard materials along with a blade without segments. For example, we have the 180LUS snap-off blade without segments in stock.
How to Cut Drywall without Dust?
To cut drywall in a straight line with a minimum of dust, you need to make a cut on one side of the sheet with enough force to cut through the paper and the gypsum core about 3 mm deep. It is necessary to cut this straight line across the entire sheet or piece of drywall, from edge to edge. Then you need to turn the sheet over and press with your hand exactly behind the line of the cut. Under pressure, the sheet of drywall will break exactly along the cut line. To finish the procedure and separate one piece from another, you simply need to cut through the paper on the other side of the drywall.
A standard sheet of drywall is 12.5 mm thick. This method is suitable if you need to cut off pieces of drywall up to 3.5 centimeters wide. If you need to cut thinner strips/pieces, you will have to make deeper cuts with a knife.
How to Cut Drywall if You Need to Cut Shapes
Cutting circles, semicircles, arcs, ovals and all kinds of curved shapes is handy with an electric jigsaw.