Use fence design to overcome obstacles

It is said, "good fences make for good neighbors." And good fences provide a margin of safety and security, as well.

While keeping your children and pets on your property -- or a specified area -- a good fence also provides reverse safety by preventing other kids and pets from wandering into your yard where unsupervised activity could lead to injury and liability.

A fence also provides a good first line of security defense by discouraging would-be intruders; visually by shielding valuables from sight and physically as a barrier against all but the most determined individuals.

Once you have decided to build a fence, it is imperative you first do some checking on local building codes and zoning laws.

Usually constructing a fence will not require a building permit. However, as codes vary in different locations, check first with your local agency that governs building codes for approval. Also inquire as to any specific local rulings and-or requirements for choice of materials, post-hole footings, picket spacing and setback distances from the street, curbs or property lines.

Besides the above, zoning laws in many municipalities dictate the maximum acceptable height for fences. Often, for example, a front-yard fence cannot exceed 42 inches. There might also be regional requirements you need to know about, such as the minimum and maximum depth of footings -- based on the frost line in your region or to meet earthquake standards (for instance) -- and safety issues for special hazards.

Fencing for special hazards includes cordoning off swimming pools, spas and wells to name but a few areas that require extra precaution. Homeowners insurance coverage often dictates that certain fence requirements be met to keep your policy in full force. So, be sure to check with your insurance agent before getting underway.

Once you've cleared all potential obstacles as far as rules and regulations are concerned, you'll need to walk the entire proposed fence line to ascertain precisely what you'll be dealing with in the construction phase.

You might find that your planned fencing will meet a number of physical obstacles along the way, as well. These can include small hills and valleys, large boulders, trees and drainage ditches. Solutions can involve moving the fence line, removing the obstacle or building around the obstruction.

In most cases -- assuming the fence line you've chosen is the most desirable for your property -- building up to, over and-or through will be most practicable. And incorporating the obstruction into your design is the easy answer.

While your fence of choice can be anything from brick or cement to metal or chain link, we've used wood for our example. The solutions offered are, in principle, the same for all other material types.

If your fence must span a low area, extend additional boards down beneath the bottom rail following the contour of the terrain while maintaining the top-rail straight and level. However, do not extend these added fence boards down farther than 8 inches to 10 inches without additional cross-rail support. Otherwise they will be subject to warping. Adding any length of drop below the bottom-rail is OK as long as you provide additional cross-rail support.

Going up and over hills and boulders uses the same basic principle, only in reverse. The primary thing to remember: any face boards extending more than 8 inches to 10 inches down from a top- or cross-rail need additional cross support to prevent warping.

If your fence crosses a small stream with running water or a drainage ditch that carries rainwater runoff, construct a grate from half-inch galvanized pipe or number 3 steel rebar. Drill the appropriate size holes in the bottom rail -- spaced about 6 inches apart -- and, after attaching it securely to the fence, insert the grate bars through each hole and drive them into the ground. You can either pre-measure the length of each bar or simply drive them in as far and deeply as possible. Or trim off the excess with a hacksaw. For extra durability, imbed the bottoms of your grate bars in concrete. This can easily be done when setting the fence posts.

Obstacles are the biggest challenge. If a tree stands in the chosen line of your fence, you can continue straight through -- without "bumping" in or out -- with a little ingenuity.

First, in addition to existing fence-post spacing, place two extra fence posts as close to the tree as possible, taking care not to damage any roots below grade. Then construct top-, cross- and bottom-rails spanning the desired distance from the tree trunk (usually about 4-inches on either side to allow for sway movement and future growth).

Then add face boards, starting from the two fence posts and working inward toward the tree, cutting final boards so they follow the trunk contour with consistent "buffer" spacing from top to bottom.

Additional support should be added, in the form of metal L brackets and diagonal braces to prevent sagging. If you wish, you can also "circle" the trunk as well with a wood-frame box or metal hoop. This will tie the two sides together (for strength) and keep them from easily being pushed in or out like a gate. Be sure to again leave adequate clearance for sway movement and growth.

Your new fence should be attractive -- on both sides. Choose its design with care and be aware that some codes even specify that the "finished" side must face your neighbor's property.