For installing a new roof, rafters are the first thing to set up. Roof rafters are the base of the roof and provide support. Everyone tries to do something productive in their spare time and weekends. It’s always amazing to work on small DIY projects
How To Cut Roof Rafters – Steps By Step Guide
Total Time: 2 Hours
Step 1: Taking Measurements
1. Measuring A Width Of Building
The first step of cutting roof rafters is to take the measurements of the building. Measure the width of the building from measuring tape. Make sure to take readings at least three to four times to bring accuracy in your reading. Measurements should be in the given format – 1/4inch (0.64cm) x 1/8inch (0.32cm) x 1/16inch (0.16). Note down the reading on a paper with the help of a pen or pencil.
2. Subtract the width of the ridge beam
The ridge beam is the vertical beam that gives the support of other rafters. Rafters are placed on both sides of it and cover half of the width. It has the extra area vertically, which has to cut down so that rafters can get attach properly. If you have a general measurement of 2×4, then the total reduction to be made is 1.5 inches (3.8cm). This is the number that should be subtracted from the width of the building. Now the new figure of number is our updated reading.
3. Adjust the measurements evenly
We know that rafters are used both sides of the building; therefore, for our convenience, we should divide all the measurements into half. So in this step, we’ll divide our updated reading from the previous step into half by dividing it by 2. If you have a rafting calculator, then you have to give the input and press the “Run” button on it.
4. Calculating the roof pitch
Roof pitch is merely the ratio of the width of the building and steepness of the rafters placed on it. It the distance between the base of the width of the building to the peak of the center of the rafters. You can calculate this distance with the help of measuring tape. If you have roofing a calculator, then you can also find out the pitch of the roof by pressing the button “Pitch” after filling the required input values.
5. Finding out the length of all required rafters
if you have a roofing calculator, then you may have already calculated the length of each rafter from run measurement and pitch. To find out the diagonal length of the rafter, you can press the “diagonal” button on the calculator. The diagonal length id from the outside width of a rafter on the base to the internal top edge of the ridge.
If you don’t have a calculator, then this step requires complex trigonometry. You also need to buy the Roofing reading reckoner: it is the table of the length of the rafter.
If you want extra length hanging out of the corner of the building, then you’ll need to add additional value because these steps and calculators are designed to make rafters with the base connected to the top edges of the walls.
6. Measuring the rise of the roof
The rise of the building is the total tallness of the building. The rise of the roof equals the height of the ridge beam. The height of the roof can be calculated by subtracting the height of the wall from the total height of the roof to its peak. If you have a roofing calculator, then you can find out the value by clicking on the “Rise” button.
Step 2: Plumb Cutting
1. Fixing stair gauge
You can purchase a stair gauge and framing square from your nearby hardware store. Now place one stair gauge on the vertical part of the framing square at the distance of seven inches. Similarly, place another part of the stair gauge on the horizontal part of the framing square at a distance of twelve inches. It will give the angle cut to the ridge for support and inclination.
2. Mark the plumb cuts
Plum is a cut made at the top of the rafter. Set the framing square at the end of the rafter, which is supposed to be at the top, with the tongues facing the top of the beam. After attaching the stair gauge to the framing square, the outline of the plumb is accurate.
3. Sawing outlines
You can use a handsaw or circular saw for sawing along the outline of the plumb. These tools are readily available at your nearby hardware store. If you use a circular saw, then you need to first clamp the rafter on the workbench or sawhorses for getting the precision and smoothness of the work. If you decide to use the handsaw, then you need to use the front and back motion of the hand periodically. Take the tool in your commanding hand and use it firmly. Don’t apply much force or increase the speed of the motion as it can the area outside the outline frame.
Step 3: Birdsmooth And Tail Cuts
1. Measuring the diagonal length of a rafter
In this step, we will measure and mark the diagonal length of the rafter like in the earlier step. Measure the length with the help of measuring tape. Fix the one end of the tape at the long end cut of the rafter and place it along the other end. Now mark this length with a pencil directly on the wood. During the installation of a rafter, this end will be attached to the ridge beam. The diagonal length of a rafter is obtained by subtracting the overhanging length from the total length of the rafter. Marking of the diagonal length of a rafter gives us the precise positions of tail and bird’s mouth cut.
2. Making Birdsmouth cut mark
In an earlier step, we placed a stair gauge on the tongue of the framing square, which is the short edge of the rafter. Now align the framing square with the stair gauge in such a way that it gets to coincide with the pencil mark of diagonal. Keep a hold on the long end of the framing square in such a manner that other straining gauge should rest against the wall. Now mark the length of the tongue on the width of the rafter with the help of a pencil.
3. Depth of a bird’s mouth
Measuring the depth of the bird’s mouth is an easy step. You have to measure the outside width of the wall. Mostly the depth is around 4 inches (10cm). For 2×4 framing, the width is 3.5 inch(8.9cm), and the outside sheathing is 1/2inch(1.3cm). The sheathing is the outer width of the wall, which is formed by the panel or extra sheet.
4. Setting the position of framing square
Take the long side of the framing square and rotate it to 180 degrees such that the right angle of the framing square is pointing in an upward direction. Now mark 8 inches (20cm) mark on the framing square, and mark should coincide the tail cut on the rafter. Now mark the bird’s mouth cut 4 inches (10cm) on the frame and trace it with the help of a pencil. If your bird’s mouth cut is not 4 inches, then you can either shorten the length of the framing square or increase the length of the cut desirably.
5. Measuring the length of overhanging rafters: for measuring the length of overhanging rafters, you have to slide the framing square to your desired length from the previous original position. The framing square must intersect the bird’s mouth cut outline on the rafter.
6. Marking tail cuts
Don’t disturb the position of the framing square and trace the tongue (short end) of the frame with the help of a pencil. In this step, the stair gauge will help to hold a framing square at a required angle. Now, this mark will show the last end of your rafter, which is supposed to be hanged outside the wall, and the rest mark is the. Now the final step is left that is to cut the rafter according to the marked outlined made on it.
Step 4: Cutting Roof Rafters
1. Sawing bird’s mouth cut
In this step, keep in mind that we don’t have to saw like plumb cut. We don’t need to cut all way through the rafter wood. Now next step is to make tail cuts following the traces carefully along with the outline marks. Use circular clamps to make more precise cuts. Clamp the board on the workbench or sawhorses, which can be available in any hardware store.
2. Sawing tail cut
Using a handsaw or circular saw, cut through the marking cut made in the earlier step for a tail cut. Use a firm hand and cut the rafter precisely with your dominant hand. When you are done with cutting, then the extra part of the rafter wood will fall.
3. Cutting all the other rafters
Apply the same procedure to cut all the left out rafters. The same technique as above given steps will be used for plumb cut, tail cut, bird’s mouth cut. The number of rafters increases according to the length of the roof. Generally, the distance between each rafter is 24 inches (61cm). Keep in note that the number of rafters required will always be in even number.
Tools Required To Cut Roof Rafters
- Roofing Calculator (recommended)
- Tape measure
- Framing gauge
- Stair gauge
- Safety goggle
- Handsaw or circular saw
If followed, all the steps mentioned above correctly and with full safety measures, then installing a new roof at the house can become manageable. The first step of installing a new roof is fixing the rafters; therefore, by selecting rafters at home, we can cut half of our burden. Please handle all the hardware tools with precautions and always keep a first aid kit near you. Also, wear gloves and eye goggles during swaying.