How to Estimate and Build a Garage Awning

Estimating the Awning

• 1

  Measure the height, depth and width of the area the garage awning will cover using a tape measure. Note the measurements on a piece of paper. Sketch a plan of the garage awning. Include on your sketch one roofing joist every 6 inches along the roof and a concrete foundation for each of the four vertical support posts.

• 2

  Note the amount of each material you will need to undertake the job. Materials include sand, cement, 2-by-4 lumber, roofing slates, 6-inch nails, clout nails, underfelt and 2-by-2 lumber. Add an extra ten percent to the amount of wood required for the job, to allow for lumber replacements due to cutting errors.

• 3

  Consult local and online price lists for DIY materials. Multiply the amount of each item on your list with the cost of the items from your price lists, using a calculator. Note the prices on a sheet of paper. Add up the total cost of each item using the calculator, to determine the estimated cost of the garage awning.

Building the Awning

• 4

  Clear the area where the awning is to be constructed of furniture, grass or any other items. Dig out the topsoil down to 6 inches below ground level along the edge of the awning nearest the building, using a spade. Dig down to a depth of 8 inches below ground level along the opposite edge, and taper depth you dig down to between these edges. Compact the soil with a plate compactor.

• 5

  Dig a hole 1 foot deep in each corner of the awning area. Cut four pieces of 2-by-4 lumber to the desired height of the awning plus 1 foot, using a circular saw. Mix a batch of concrete from 1 part cement, 3 parts sand and 1 part water. Plant one of the 2-by-4 pieces vertically in each hole. Fill the holes with cement. Wait 48 hours for the cement to dry fully.

• 6

  Cover the compacted ground with plastic sheets. Pour gravel on top of the sheets up to ground level. Rake the gravel flat to provide a firm surface underneath the awning. Alternatively, prepare another batch of concrete and pour this onto the compacted dirt up to ground level. Wait at least 48 hours for the surface to cure enough to continue working on, if you choose a concrete floor.

• 7

  Cut two pieces of 2-by-4 lumber to the width of the awning. Cut two pieces of 2-by-4 lumber to the length of the awning plus 2 inches. Draw a 2-by-1-inch rectangle in one corner at each end of both awning length pieces, using a pencil and ruler. Cut out the rectangles with a jigsaw, leaving a 2-by-1-by-4 inch notch in either end of the wood.

• 8

  Connect the awning length pieces to the awning width pieces via the notches you just cut to form a rectangular frame equal to the length and width of the awning, and 4 inches tall. Screw the 2-by-4 pieces together using two countersunk 4-inch long screws per joint. Raise the frame to the top of the 2-by-4 pieces. Screw the frame to the top of the posts using 1 lag bolt per post.

• 9

  Cut a piece of two-by-four to the length of the awning plus 2 inches. Hold the piece horizontally on the side of the building 12 inches above the rectangular frame, with the 4-inch long faces vertical. Drill a hole through the wood and 4 inches into the wall every 6 inches along the length of the wood. Push a wall plug into each hole in the wall. Screw the wood to the wall using 6-inch long screws.

• 10

  Measure from the wall just above the wall joist you just made, to the outer edge of the rectangular frame and add 4 inches. Cut enough pieces of two-by-four to this length to place one on either end of the wall joist and one every 6 inches in between. Stand the pieces balanced along the wall joist and the edge of the rectangular frame, with the 4-inch faces vertical.

• 11

  Draw a vertical line down the end of each piece nearest the wall using a plumb line, to find how much needs to be cut off for the wood to press flush against the wall. Cut along the line with a jigsaw. Stand the pieces on the wall joist and frame again. Draw a vertical line down the pieces where they connect with both the wall joist and the frame.

• 12

  Draw horizontal lines across each piece through the middle of the vertical lines, to show the size of the notch that needs to be cut for the pieces to sit flush on the wall joist and frame. Cut the notches out using a jigsaw. Spread the pieces along the frame with one on either end and one every 6 inches in between to form the roof joists.

• 13

  Screw the pieces to the wall joist and frame using one 6-inch long screw per joint. Cut enough pieces of 2-by-2 lumber to the length of the awning plus 2 inches to place one piece across the roofing joists every 4 inches down the width of the roof.

• 14

  Screw one beam to the top of the roof and one beam to the bottom of the roof using 3 inch long screws. Screw the other beams to the roof with 2-inch gaps between each beam. Cut sheets of underlay to the length of the awning plus 2 inches. Nail the first sheet across the bottom of the joists using clout nails and a hammer.

• 15

  Nail the second sheet above the first with a 1-inch overlap. Continue nailing sheets across the roof with 1-inch overlaps until the roof is covered. Nail a row of slate tiles across the bottom of the roof using 1-inch roofing nails and a hammer. Nail the second tile across the roof with a 1-inch overlap over the first row of tiles. Continue to nail the tiles to the roof until the roof is covered.