Instructions for Constructing Roof Trusses for a Shed

It’s common for shed construction to bog down as people try to figure out how to construct a roof. The walls, being square and upright, appear to be the more accessible part. Still, many individuals get into trouble when faced with sloping roof angles, rafters that dangle over the borders of the walls, or cutting the birds’ beak on a rafter. This post will hopefully remove some of the mystery from constructing a shed roof by outlining the fundamental processes involved in making a roof with a 4/12 pitch and a peak in the middle.

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Do Some Wall Plumbing

The first thing to do is check to see if the walls are plumb and square, which means they are level from top to bottom and the corners are at right angles. These two components are crucial since the walls cannot be moved once the roof trusses or rafters have been placed.

Using a level, adjust the shed’s walls until vertical before reinforcing them with leftover timber. Larger sheds are more likely to have crooked walls since there is more room for objects to shift out of alignment.
Using a diagonal measurement from corner to corner, ensure the shed’s walls are square. To make the two dimensions equal, round the corners in or out as necessary.

Layout The Trusses For A Shed Roof

The next step in learning how to build a shed roof is designing the rafters, which is done after the shed walls have been squared up. You may be overthinking this. If your shed plans don’t include a roof truss diagram, the simplest way to construct a roof rafter is to draw it to scale on the floor, then cut it to size and nail it into place. The 4/12 pitch is the standard for shed roofs. This means that the top extends 12 inches out from the wall. For every 4 inches, it rises vertically. Manufacturers of asphalt shingles often set the minimum acceptable slope at 4/12. Follow these directions to sketch a rafter for a roof with a 4/12 pitch.

Sketch the shed’s rafters outside.

Draw a line on the ground the same length as the shed’s width. Let’s refer to this as the Linear measurement of shed width.
Make two marks on the Width Of the Shed Line at the exact width you measured on the top plates of the walls.

A second set of marks should be made by measuring 4 inches from the outer spots on each end. These will be our inner and outside points of reference. To indicate the base of the rafters for the shed roof, draw a line from the two internal lines at a 4/12 angle toward the center.
Mark the position in the middle of the Width Of the Shed Line between the two outside points.
Create a perpendicular line to the Width Of the Shed Line, starting at the center point. Take a foot or two and draw this line perpendicular to the first. If your shed is quite broad, you may need to extend it.
Connect the Dots on the 4/12 Line

The roof rafters will rest at an angle of 4 degrees and 12 inches. On the Line Denoting the Width of the Shed, draw a triangle.

Finding the center of the shed is as easy as measuring inward from the outermost and innermost points on the Width Of the Shed Line by 1 foot.
Make a perpendicular line with the square 4 inches up from the new 1-foot mark, then make a mark there.
Draw a line with a straight 2×4 from the mark 4 inches in, up 4 inches, and perpendicular to the Width Of the Shed Line. Next, proceed to the opposite end of the Width Of Shed Line and do the same thing there. The point where the two angled lines meet is where the center line you created comes into play. Check your measurements and draw new lines if the three don’t meet.
The two diagonal lines denote the rafters’ lower edge, and the fantastic news is that you’ve already written out on the ground all the angles you’ll need to cut out your rafters. They need only be moved to the first rafter before the shed roof can be framed.

Put the rafters’ lines up from the floor.

A 24 with enough length to go beyond the notches on the Width of the Shed Line and the gaps where the three lines join on the perpendicular line will suffice for transferring the angles and lines.

The board should be positioned on the edge of the triangle above the line.
Put the markings from the floor onto the board with the help of your square.
Birds’ Beaks and Tops Snipped From Rafters

The board’s two ends are shaped differently from one another.

The top or peak end must be removed for the two rafters to butt up to each other at the point where they meet in the middle. Cut the board at the top with a circular saw.
Return the board to the lines and check that the peak is level with the vertical and the rafter line.
The rafter’s lower end will be given a bird’s mouth cut to rest against the shed wall and extend beyond it to create an overhang.
Trace a horizontal line of 4 inches from the outer mark to the Width Of the Shed Line, then down and off the board to create the bird’s mouth shape at the rafter’s bottom end.
A “seat” will be formed in the rafter, allowing it to rest against the shed’s wall in this configuration. A circular saw will remove the marked area from the rafter’s lower end. To complete the cut, a hammer and chisel will be required.
Position the rafter above the floor plan and double-check the cuts against the lines. When the first rafter has been cut out, and you’re satisfied with the shape, set it on another piece of 2×4 wood and trace the cut lines to create a second rafter. After cutting out the second rafter, position them on the ground by the lines on the drawing to ensure a snug fit.
Put a Gusset On It

A gusset is a wooden connector used to join adjacent rafters. Make a gusset out of plywood or O.S. B. to join the two rafters at the top.

Double-check that the rafters are standing squarely on the ground lines.
Make a gusset by sawing off a strip of O.S.B. From the apex; the gusset should reach down the rafters for about 7 inches, double the breadth of a 2×4 rafter.
Join the gusset to the top and bottom of the roof. Drive three nails into the rafters through the O.S.B.
Verify the bird’s mouth cuts on the shed roof rafters by mounting them on the shed walls.

If the rafters meet your standards, you can use them as a guide to construct the remaining rafters for the shed roof. The rafters for the shed roof should be placed every 24 inches along the shed walls, and one pair should be placed at each end. After the rafters are up, you may begin framing the shed’s roof.

Read this page at http://www.icreatables.com/sheds/how-to-build-shed/shed-build-roof-build.html for more details on constructing shed roofs. For instructions on creating a shed roof or a rafter layout to use as a guide, check out http://www.icreatables.com/sheds/shed-plans.html. Shed Blueprints that include a framing diagram for the rafters.

linda