Site Evaluation for your Shed

Site Evaluation for Your Shed

Written by Frank McGill.

There are four main things to consider about a potential site for your barn or shed:  Access to both roads and utilities, soil type, drainage, and topography.  If a number of places on your property satisfy these criteria, you might also consider other factors, such as solar orientation, weather protection, and the direction of prevailing winds.

Access to Roads

Good roads are expensive to engineer and build, even thousands of dollars per mile if you have to blast bedrock.  They involve excavation design for proper drainage, and careful selection of materials.  You cannot just dump loads of gravel onto grass or bare earth and expect it to serve as a sound road surface for very long.

Also, once a road is in place, it has to be maintained.  Gravel needs to be dressed every other year or so because the finer pieces sift down into the larger rocks.  Blacktop cracks need to be sealed to prevent frost heaving that can tear apart all your costly work.

If you can position your shed or barn so that is doesn't need a new road built to it, all the better.  If you want to build your barn away from existing roads and your region endures winter weather ( and a muddy spring), you will likely struggle with access over rutty roads and mud unless you construct a solid road bed.  You will have to decide whether that's a price you are willing to pay to put off spending what it takes to build a good road.

Access to Utilities

You should always consult a licensed electrician in the planning stages of your shed.  Depending on your circumstances, you may also need to contact the power company.  Local utilities often regulate the maximum distance between a meter and a breaker panel and whether you can run an outdoor circuit to your shed or barn directly from you house's main service panel or whether you need to have a separate sub panel installed in the barn.

Whether or not your local government requires it, all work should conform to the requirements of the National Electrical Code (available at local libraries).  If you will be keeping livestock, bringing water to your barn is an absolute necessity.  You're probably not going to want the expense of a new water main and septic system just for your barn, you'll want to hook it up to your house's system, if possible.  In regions with cold winters, water-supply pipes need to be buried 4 feet or more in the ground; the closer you are to your well and septic system, or to the municipal water and sewage lines, the less time-consuming (and costly) this digging will be.  Remember that some areas impose very strict standards for septic systems, and require perc tests, special permits, and inspections.  When it doubt, have a talk with your local building inspector before any work begins on your shed.


If you have a garden, you may already have an idea of what type of soil you have on your property -- whether it's mostly sand, clay, silt, or loam.  Before building a large structure, however, obtain a copy of a local soil survey map (example below), which should be available from the Cooperative Extension Service, to find out exactly what type of soil on which you'll be building.  The soil types are drawing onto aerial photographs with a key that explains the qualities of each soil type, including engineering properties and how suitable it is for different types of construction methods.

Soils are rated for their load bearing capacity - that is, how much weight per square foot they can support without having to be modified with soil stabilizers such as gravel, stepped landscaping, or retaining walls.

Bedrock, the most stable building surface, has the greatest load bearing pressure rating.  Sedimentary stone, such as sandstone, and gravel support slightly less weight.  Sand silt, and clay soil will support much less.  Depending on your soil type, you can increase the width of the foundation footings to spread the load or even modify the soil itself by bringing in fill from elsewhere - which is an expensive option.

If you have any doubts about the bearing capacity of your soil, consult a soil engineer and the Cooperative Extension Service.  Building on soil that can't support your shed will cause it to settle, crack the foundation, and rack the walls.


Soil must drain thoroughly, especially in areas where the weather reaches freezing temperatures.  Otherwise, moisture retained in the soil will freeze and cause frost heaving.  Frozen soil can increase in volume as much as 25 percent, which presses the soil (and your barn's foundation) upward.  In cold climates, prevent damage from heaving by installing your footings below the average frost depth, which is available from your local building department.

Its also important to have good drainage around your structure for water that runs off the roof and groundwater that may run downhill and be blocked from its normal path by your structure.  The soil around your shed should slope away from the foundation, generally at 1/4 inch or more per foot for at least 6 feet.  If needed, a swale, or shallow depression, can be used to direct surface water.  A perimeter drain made of perforated pipe can be used to direct groundwater away from your building into a drainage ditch or collection pond.


The topography of your shed site is the three-dimensional shape of your lot including major physical characteristics, such as standing water, large rocks, and trees.  You can alter the topography of your lot, but it is expensive.  Generally, its better to adjust your shed to the topography.

A sloped site presents challenges when designing your foundation slabs.  For example, you must excavate a flat, which could mean building a retaining wall.  For walls, you can excavate the slope or use a stepped foundation.  However, a sloped site isn't always a bad thing.  If the lot slopes to the south, for instance, you will have a site that's warmer than surrounding flat areas because the ground sloping 10 degrees to the south receives the same amount of solar radiation as level ground 700 miles to the south.  Plus, mildly sloped sites are good for drainage, so if you prepare your shed's perimeter drains and swales properly, you will have a well drained site and dry barn.

Sun and Wind

In the Northern Hemisphere, the climate is slightly warmer on south facing slopes and slightly colder on north facing slopes.  To reap gains from passive solar heating, buildings should have the longest dimensions running approximately east and west with the most windows on the south side and few on the north.  In hot climates, you'll want to do just the opposite to prevent solar gain.  Of course, other elements in your environment may not permit you to orient your shed this way.

When you position your shed, note that positive pressure from the wind will drive cold air into the barn, and negative pressure on the far side will suck warm air out of it.  As you orient your barn for sun and wind, keep in mind that, for the winter, you want to expose the wall with the most glazing to the south to collect solar heat while exposing the fewest openings to the ends of the barn that are perpendicular to the prevailing wind.

As for trees, there are different scenarios for dealing with either year-long prevailing winds that come from one direction or prevailing winter winds that shift from north to south between winter and summer.

The arrangement of trees is important, but so is the type of tree you plant.  Deciduous trees bear leaves in the summer but lose them during the cold winter months.  These trees are excellent for the south side of your shed because their leaves will shield the roof from the harsh summer sunlight and heat, and when the leaves drop, admit sunlight and heat in the winter.  Carefully placed after close observation of prevailing winds, deciduous and coniferous trees can be used to direct cooling breezes toward your structure in the summer and block cold winds in the winter.

Power to the Site

You can often bring power to saws and drills by running a power cord from a nearby house.  Just be sure the cord is heavy enough gauge to support the amp rating on your tool.  An undersize cord can deprive a tool of the needed power and ruin the tool.  This is because power encounters resistance in the cord and drops off over longer distances.  You decrease this resistance by using heavier gauge wire.  Generally use 10 or 12 gauge cords.  They are not as flexible and light, but they will protect your tools in the long run.

If you can't get power nearby, you have two choices:  make power with a generator, or install a temporary power pole.  This setup includes a conduit mast, a meter base and meter, a turn off switch, GFCI breakers, some outlets, and a rod hammered into the ground to act as a ground.  Some utility companies will set up these poles for you for an installation fee and monthly power consumption charge.  They will often have a minimum charge.  An electrician can make one for you, but it will still have to be inspected by the utility company before power is turned on.  The building inspector may also want to take a look before it is approved for use.

If you do the work yourself, be sure to check specs with the local utility because there are often strict requirements about weatherproofing, pole height and depth into the ground, minimum distances from the service to the center of the street, and pole placement on the site.  After you have the pole approved and power is flowing, you'll have to distribute it through the site through GFCI protected cords and weatherproof outlet boxes.

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2870 Ashwood Road
Columbia, TN, 38401