How to Build a Roof for Your Shed


A Guide on DIY Roof-making

For any building one if the most essential parts of its basic structure is the roof. It gives anybody and anything inside protection from the elements, the cold, the heat, critters and so on. Usually the roof is made from a durable material so that it is long lasting such as brick or galvanized steel even but it can also be made from something like treated wood, it can depend on what the structure is and its style. When building a new shed or if doing renovations to one that includes new roofing here is a guide to ensure you get yourself a solid roof that offers the protection needed.

how to build shed's roof
Before you start

tin roof lean free standing

Before you take on any kind of DIY it is important to make sure you have what you need including tools, materials and such. The process will take longer if you have to stop to get something you forgot. Materials include – proper roofing nails, fasteners for holding together metal, clips, rafter ties, asphalt shingles, metal flashing, drip edge, roof trusses, tar-paper, scaffolding and exterior plywood.
Tools include – nail canvas belts, wrenches, screwdrivers, framing square, framing hammer, claw hammer, tape measure, a level, pens and pencils, ladders, nail puller, drills, chalk line, hacksaw, string, plumb bob, a saw horse, finish hammer, handsaw, chisel, clam, nail gun, plans or blueprints, nail set, staple gun, caulking gun and tin nip.



Step one – squaring up


To make sure all the walls are squared up, they need to be completely straight as when the rafters or roof trusses are put on that is the position they will remain in. Also it is important for your roof’s stability. Use your level on the side of the walls of the building and move the walls by bracing them into place. You can check walls are squared also by measuring from one corner to another going across diagonally. Then do the same for the other diagonal and make sure both measurements are equal.

Step two – designing the rafters


When the walls of your shed are squared the next job to take on are the rafters for the roof. Some shed plans come with the roof trusses drawn in already but if yours does not it is quite a simple task. On the floor draw out a full size version then cut the rafters so that they fit into your literal floor plan! For sheds most roofs slope at 4/12 which means that as the roof slants up for every 4 inches of vertical climb there is then 12 inches that go over horizontally to the wall. This 4/12 measurement is the least amount of slope you can have for makers of shingles to still offer a guarantee.

Drawing it out

  • Draw a straight line on the ground that is the same length as how wide the shed is. This is called the Shed Width Line.
  • Measure the shed’s width from the wall’s top plates and make two marks on the Shed Width Line to show the distance between them.
  • From the outer marks on the Shed Width Line measure out another 4 inches on each end and mark those in. We now have inner marks and outer marks. From the inner marks draw at the 4/12 sloping angle to the center. This now shows the bottom of the rafters.
  • On the Shed Width Line find the center between each outer mark and mark it.
  • Perpendicular to the Shed Width Line from the center mark draw another line making it a couple of feet long. If necessary (you have a very wide shed) it can lengthened further later.
  • Now to draw the 4/12 line you basically have to draw a triangle on the Shed Width Line. Do this by finding the two inner marks and measure to the center a foot long then place a mark. Using the square make another perpendicular line going straight up by a measure of 4 inches and mark that spot.
  • Using a 2×4 from the mark of 4 inches draw a line through that to the line that is perpendicular to the Shed Width Line. Do the same on the other end of the Shed Width Line and those two angled lines should meet at the center line. If there is no meeting then the measurement went wrong somewhere so check them.
  • The roof rafters bottom edge is represented by the two lines that are angled. Now that all the angles you need are drawn out on the floor all you need to do is transfer that to the actual rafters now and you are a lot closer to getting your roof framed out.

Step three – transferring the lines from the floor plan to the rafter


To transfer the lines and angles you have created on the floor onto your 2×4 just lay one that is long enough to go past the Shed Width Line and its marks and past the lines that meet on that line that is perpendicular to it. You should put the board on the triangle outside of the line on the upper side. When moving the marks from the floor to the board use your square.

Step four – Cutting out the peak and bird’s mouth

It is important you get the ends of the board cut correctly and remember that each end is cut in a different way. The peak or top end of the board should be cut so that when the two rafters meet in the middle they can butt up. The peak takes a circular saw to cut. To make sure the peak is aligned with the bottom of the rafter line and the vertical line put them back on the floor plan to check.

The other end of the board, the lower end will have to be cut with a special cut that is known as the bird’s mouth cut. These cuts ensure the rafters’ bottom ends will sit on the wall of the shed and then go past a little to create the roof’s overhang. On the bottom end of the rafter trace along the Shed Width Line going horizontally for 4 inches heading to the outer mark. Then go down coming off the board to create a shape referred to as a ‘seat’. Called this because it ‘sits’ on the wall of the shed. Use a circular saw to cut the shape out and and a chisel and hammer will help you give it a proper finish.

Check a rafter on the floor plan and check your cuts against the drawn out lines, and if you are content with its shape put the rafter you just cut out on top of another 2×4 and trace out what you just did to the first onto the second. Then cut out that rafter too and place both on the lines on the floor to check they make a good fit against one and other.

Step five – Attaching rafters together


The piece of wood used to attach rafters together is called the gusset. To create a gusset you can use O.S.B or plywood and then use it at the peak of the two rafters to attach them together. Make sure though that the rafters are properly aligned using the drawn lines on the floor. A gusset should go from the peak down about 7 inches, or about twice as much as the 2×4 rafter is. Use three nails into each of the rafters to fasten the gusset then check them on the walls of the shed to make sure your bird mouth cuts are good.

Once you have created a pair of successful rafters you can use them to build the rest of the roof. There should be a set of rafters at either end of the roof and then at every 24 inch or 2 foot interval there should be another pair. Once you have them all cut and aligned you are read to frame the roof of your shed.


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