Overlapping Board Fencing

Board FenceA board fence is a traditional fence which can provide privacy (if high enough), is fairly attractive and robust and is fairly easy to maintain.

The method of post and rail construction are given on this page, this page on Board Fencing addresses the cladding of the posts and rails.

There are two basic choices of planking available:

  1. Feather-edged timber.
  2. Sawn, square timber.

Feather-edged timber

Feather edged board timberFeather-edged timber is rough sawn and each plank is tapered across its width, various widths are available, typically ranging from 125mm (5 inch) to 225mm (9 inch).

The tapering typically 18mm (0.75 inch) to 6mm (0.25 inch).

Sawn, square timber

Square edge board timberSawn, square timber is rough sawn and each plank has a uniform thickness (normally 12mm (0.5 inch) to 18mm (0.75 inch)) across its width, the choice of widths typically being from 125mm (5 inch) to 225mm (9 inch).

Both types of plank are normally erected vertically with an overlap by about 25 mm (1 inch) with the thicker edge of feather-edged planks being on top of the lower plank, and using one nail passing through both planks into the rails. Alternatively, sawn, square timber can be butted up 'edge to edge' and each plank nailed separately to the rails (see separate page).

Gravel board

Where the bottom of the fence is to ground level, a gravel board should be fitted below the fence planks. The gravel board is normally of a hard timber (such as oak) to withstand the damp rising from the ground. If the gravel boards do rot, they can be replaced without having to dismantle the complete fence. Where a fence is erected above masonry or concrete, there should be a clearance of at least 5mm (quarter inch) under the gravel boards - this should prevent the bottom of the boards becoming waterlogged providing it is kept clear of material build-up.

Fence boarding

fencing cant rail optionsThe easiest method of erecting a board fence is to use cant rails on the front face of the fence posts, this allows a continuous run of planking along the full length. An alternative method is to fit arris (or cant) rails between the posts, flush with the front face, the planking can then be fitted to the rails and across the front of the posts.

Another alternative method is to fit arris (or cant) rails between the posts, but set back from the front face, and then fit the planking to the rails between the posts - personally, the former arrangements giving a continuous run of planks making it easier to put on the planks and the finished fence looks better.

fence overlap step guideBefore starting to assemble overlapping boarding, make up a stepped guide (as right) so that each board can be easily set-up - the depth of the step needs to be the width of the plank less the desired overlap.

Before nailing the first and each subsequent plank, check:

  • The length of the plank - it needs to go from the top of the gravel board to the desired height.
  • The angle of the bottom of the plank - if the fence is not on level ground, the gravel board will be at an angle, the bottom of the plank must reflect this angle.
  • You need to think about these points concerning the top of the planks:
    • If the fence is on level ground, the planks can be cut to size before fitting.
    • On sloping ground:
      • The tops can be cut at an angle before fitting to give a smooth line,
      • The tops can be left square to give a 'stepped' appearance - this is generally best suited where the slope is gentle - where each sequential plank has a step of less than about 6mm (0.5 inch).
      • The tops can be left to be tidied up after the fence is complete.
      • Have a look at this other page which shows some examples of what people do on sloping ground.

With the posts, rails and gravel boards in place, position the first plank in place at one end of the fence. With an overlapping plank fence, the first plank can be fitted flat to the rails or a small strip (the same width as the intended overlap - about 25mm (1 inch)) of suitable timber placed under one edge (the edge away from the rest of the fence) to give the same angle of lift as the rest of the fence planking. With feather-edged planks, the thick edge needs to be the first edge nailed and must go away from the rest fence. When you have checked the first plank to make sure that it is the right length and the ends have been trimmed to suit the gravel board and the top edge (if necessary):

  • Offer up the plank, keep the plank about 3mm (1/8 inch) off the gravel board, and with a thin strip of planking underneath to get the face angle correct.
  • Use a spirit level to make sure that the plank is vertical.
  • Use galvanised nails to 'tack' the plank to the rails/post - with plain galvanised nails, drive them in at an angle - alternatively, use galvanised annular ring nails.
  • Check again with the spirit level that the plank is still vertical after tacking, if it is - drive the nails home, if it is not vertical, adjust the plank as necessary.

For each subsequent plank, check the cut angle of the bottom and the length - offer it up to overlap onto the previous plank, use the spacer to set the position horizontally, check the line of the top of the plank with the previous plank and nail it in place so that the nail is not too near the edge of the top plank, but the nail does go through the edge of the plank underneath and into the rail. Check every fourth or fifth plank with a spirit level to ensure that you continue to fit them vertical, if necessary, adjust before continuing.

To trim the top of the fence if this was not done during construction, stretch a chalked string line along the top of the fence against the planks and pluck it to mark a line. Saw along the line to trim the top of the fence to a single line.

When you have finished the fence, checked the fence to ensure that nails have been driven home on each each plank, on each rail/post.

Treating the fence with timber preservative.

The final job is to apply a good quality wood preservative. Modern wood preservatives are available in various colours, these tend to mellow after a bit of weathering, but it's still worth thinking carefully before choosing a bright/vibrant colour.

Before applying the preservative, read the manufacturer's instructions carefully and take any recommend precautions - often this may entail protecting the surrounding soil and garden plants and the use of appropriate safety gear (goggles, gloves etc).

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