Pouring a small concrete slab to support an outdoor fuel oil tank is something that almost any homeowner can do successfully. The key to pouring a slab that meets code requirements is a thorough understanding of your local building code. Before beginning this project, check with your local building codes department to get a copy of the code requirements for your community. The California code requirements are typical for most areas.
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Locating the Slab
According to the California Fire Code, CFC 2001 Edition, you should position the slab so that it does not come within 5 feet of a roof overhang, or within 5 feet of any windows, doors or any other opening in the structure. Openings in the structure include any types of vents, such as a dryer vent. The slab also must not be within 5 feet of your property line. Also, do not locate the slab next to a driveway or vehicular path unless you provide protection for the tank against accidental damage from vehicular collisions.
Submit a Site Plan
Before beginning to pour the support slab, submit a site plan to the fire department for approval. You will need to submit a plot plan showing how the slab will be positioned in relationship to your home and the slab specifications provided with the fuel oil tank. The slab specifications plan is stamped by the engineer who prepared it and is required before you can begin pouring the slab. One of the most important specifications is the thickness required to support the tank's weight when full of fuel oil. The inspector will check slab thickness and will "green tag" a slab pour that does not meet minimum thickness.
The easiest way to ensure your pad will be of the correct thickness is to use 3/4-inch plywood cut to a width that equals the required depth of the pad. Cut the plywood strips to lengths that match the length and width of the poured slab. Using such a form also makes it easy to construct a flat slab because the plywood strips act as a guide for the screed board -- a board used for smoothing the surface of the poured pad. While a pad can be poured directly onto the ground if the ground is flat, you may want to consider digging out a small recess in which to pour the slab.
Mixing and Pouring
If working with concrete is new to you, your best bet is to buy one of the premixed varieties. With premixed cement, you need only add the specified amount of water and mix. Mix it in a large wheelbarrow, using a shovel or hoe. Alternatively, rent a small powered mixer from your home center. Once poured, let the slab cure for at least 72 hours before placing the fuel tank on it.