How to Build a Wooden Arch Kit
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Highlights:
- Materials needed:
- 1. Mark out the area.
- 2. Measure and mark the opposite corners.
- 3. Position support for posts.
- 4. Construct the frame.
- 5. Lay the two sections of lumber for one side of the roof neatly together.
- 6. Lay out the posts for one side on the ground.
- 7. Make sure the beam end overlaps the two post tops by the same amount.
- 8. Repeat steps 3 and 4 for the posts and beams on the opposite side.
- 9. Set up the frame and place the rafters.
- 10. Measure out and mark where the notched rafters should lie.
- 11. Tap the rafters down until they fit tightly onto the beams.
- 12. Add finishing touches.
A wooden arch is simple to construct, and when built from treated lumber it makes a long-lasting support for plants. Whether the roof is pitched, as below, flat and pergola-like, or rounded, the procedure remains the same; mark out the area, assemble and erect posts and beams, then place the rafters on the top. These instructions are for a kit with 8 feet (2.4 m) posts set 4 feet (1.2 m) apart left to right, and 1 foot (30 cm) deep.
Keep in mind: When working with lumber, make sure it is treated — including at the sawn ends — with a preservative to prolong the life of the wood. Always attach joists with galvanized nails or rustproof screws, and use metal "shoes" to prevent the bottom of wooden posts from rotting in damp ground. Ensure your safety by never sawing wooden joists in the air on a stepladder; instead move to ground level and saw on a firm bench.
Materials needed:
set square
hammer or mallet
club hammer
marking pegs
string
driving tool
level
drill
screwdriver
4 spiked metal post supports or "shoes"
4 lengths of treated, sawn lumber for beams, as supplied
4 lengths of treated, sawn lumber for posts, as supplied
6 lengths of treated, sawn lumber for rafters, as supplied
rustproof screws or galvanized nails Wood preservative
1. Mark out the area.
Use a large set square or framing square to measure out the exact position of the archway: this ensures that the 2 sides of the arch are parallel to each other and that the front and back are square to the sides. Using a mallet, drive in a marking peg at 2 corners, winding the string around the outside of the peg.
2. Measure and mark the opposite corners.
Draw the string line taut along the sides of the framing square. Check that you have measured accurately (always measure from the same points), adjusting the pegs if necessary.
3. Position support for posts.
Using a mallet and driving tool, hammer a spiked metal support for the arch posts into each of the four corners exactly where the measuring peg was. Check each one with a level to ensure it stands upright.
4. Construct the frame.
First, join the pitched beams. These lengths of lumber for the back and front arch top should be cut in a half-lap joint at the correct angle for the arch: how steep this angle is determines the pitch of the roof.
5. Lay the two sections of lumber for one side of the roof neatly together.
If the kit is not pre-drilled, drill two holes in the join. Attach with rustproof screws. Similarly, join the beams for the other side of the roof.
6. Lay out the posts for one side on the ground.
Butt them up firmly to the metal supports to hold them steady and to confirm they will be exactly parallel once erected. This also allows you to fit the top of the arch to the posts while they are still on firm ground, rather than balancing high up on a stepladder. This is possible only where the posts are not too heavy to lift once assembled.
7. Make sure the beam end overlaps the two post tops by the same amount.
Drill two holes in the first post, then secure to the beam with rustproof screws. Drill and fit the second post and beam.
8. Repeat steps 3 and 4 for the posts and beams on the opposite side.
Take care to attach each set of beams to the outer side of the posts. The two sides of the arch are now ready to set up.
9. Set up the frame and place the rafters.
With a helper, lift up the front of the arch and lower the posts into their supports. Repeat for the back. Check that the posts are straight, then screw each one into its support.
10. Measure out and mark where the notched rafters should lie.
Make sure they are evenly spaced apart. Hammer each end into place using a block of wood to protect the rafter.
11. Tap the rafters down until they fit tightly onto the beams.
Attach the rafters at both ends to the beams using galvanized nails.
12. Add finishing touches.
Sand down rough wood and treat any newly sawn edges with preservative before you plant. The metal post supports at the base will soon be hidden by plants.
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Arches & Pergolas © 2000 Dorling Kindersley Limited
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