alternative for mounting posts
When post sockets are not used to secure the posts, they should be raised above any surface which could transfer moisture to them - placing bricks under the posts should prevent the bottom of the posts from rotting.
The basic structure of the arch is the same as on for structure but has addition braces between the top cross pieces and the posts above the arch, and braces on the side to add rigidity.
Additional materials required:
- Alternative braces for the lintels 4 off, 100x25mm 0.6 long
- Additional side braces - 4 off, 95x35mm, 1.5m long
- 20 off additional 6x10cm coach bolts with large washers (for main braces)
- 20 off 6x15cm coach bolts with large washers (for side braces)
- Cut the posts to the same length as given in the main article and cut out the recesses for the lintels at the top.
- Cut and shape the timber for the lintels. Lay the posts along the ground and fit the lintels make sure that the angles between the post and lintels are right angles - use 2 coach bolts with washers at each joint.
- Cut the timber for the upper braces and fit them across the
front faces of the posts onto the lintels as illustrated to the right. Use 4 coach bolts with washers per brace - 2 at each end to secure the braces to the posts and lintels.
- Cut and shape the timber for the end rafters. Raise the two sides of the arch (posts, lintels and braces) to the vertical; assemble the end rafters between them and secure the end rafters to the posts using screw.
- On each side of the arch, ensure that the posts are equally spaced and square.
Cut and fit the horizontal side braces between the posts using screws.
On each side, fit three side braces, one about 30cm from the top, the lowest about 30cm above the ground and the middle brace equally between the upper and lower braces.
- Measure and cut the intermediate angled braces to fit between the three horizontal braces as shown. Secure each angled brace using a coach bolt through
each end and post.
- Cut and secure the middle rafters between the lintels using nails through the lintels into the end of the rafters.
Use short metal stakes:
The basic method of assembly is as described in the basic construction method for using post sockets except that rather than using post sockets to support the posts, a 'L' angled (or flat) stake is positioned next to each post and the post is secured to it.
The stakes should project about 20 to 30cm above the ground level so that at least two strong fixings can be made between it and each post.
The stakes can either be embedded in concrete or driven deep into the soil:
- Embed each stake in concrete with about 20 to 30cm in the concrete as described for the post sockets, but measure and position
the stakes on the outside on the footprint.
Splitting the lower end of the stakes, or putting a few bolts through the lower end will help give a firm anchor when embedded in the concrete.
- Drive the stakes into the soil - with at least 50 cm under the ground. The stakes can either be driven into the ground after the arch has be made, or the intended size of footprint can be measured onto the ground, the stakes driven into the the soil and the arch built up from the stakes.