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  Friday, October 31, 2014  
   
 

 
Docks and Piers
Docks and Piers

Docks have been in existence and use for centuries. They have given better water access for both residential and commercial purposes. The House and Home Magazine with the help of some of our local marine craftsmen are pleased to step-by-step guide you through proper dock building.

Step 1: Obtaining Proper Permits As with any new structure you are building you must obtain the proper permits from your local planning commission. With a dock you must also obtain permits from your local wetlands board and also the Virginia Marine Resource Commission. Applications and guidelines generally maybe found on their websites. Some marine contractors will do this for you to help you through the process.

Points to Remember: Always use galvanized or stainless steel hardware. Marine construction is a complex process requiring extensive knowledge of local conditions and should only be undertaken by a highly qualified professional.

Step 2: Hiring A Marine Contractor When hiring a marine contractor you want to look for the following specifics and ask the following questions: Do they hold a contractors license in the state of Virginia? (Searchable on the DPOR website) Do they hold a business license within the county they work? Do they have both liability and workman’s comp. insurance? Ask for pictures and references. Visit completed jobs and talk to previous customers. Brian Fletcher at Delta Marine Construction says,” Always compare apples to apples, you’re going to get exactly what you pay for.” When signing a contract with your contractor make sure your best interests are stated.

Step 3: Pilings In order for docks to be solid free standing structures their “foundation” must be placed accordingly. In salt water, round pilings must be used. Pine lumber which is primarily used is composed of two types of wood, sapwood and heart wood. Sapwood is the outer portion which is the active growth and promotes water movement and the heart wood is the inactive or “dead” center. Pressure treating the sapwood is the most effective method of protecting wood and assuring its long term performance. The chemicals which are pressurized into the pores of wood decrease the effects of water, insects, rodents, and other environmental effects of exposure. The reason round pilings are used in salt water applications rather than square is because round pilings when sawn are guaranteed to have sapwood on all” four sides.”

Pilings are normally placed vertically, 7 feet length wise apart from center, anywhere from 4 to 6 feet apart in width and at least8 feet of piling must be embedded deepen good soil. In our bay and river region our soil is not always good and can be embedded with iron ore. Iron ore can promote problems as it can cause pilings to back themselves out of their placement. Water level extremes, tidal histories, and thorough soil tests should be completed prior to beginning. Proper size pilings should be ordered accordingly, cutting pressurized lumber can expose untreated sections leading to decay and eventually replacement.

Thanks to our modern technologies marine contractors wouldn’t be as successful without the use of their pile drivers. There are many different types of pile drivers and they use different methods to perform the same tasks. The air or steam method engages a drop hammer powered by compressed air or steam. Hydraulic fill displaces the soil with water and the piles are then placed in the hole it creates. The vibratory hammer is mechanically connected to the piling and then it drives the piling downward by oscillating it through the soil. One of the only vibratory hammers used in the Chesapeake Bay Region is owned and operated by Brian Fletcher owner of Delta Marine Construction. The use of a vibratory hammer keeps from creating air pockets like other pile driving methods may. Air pockets can lead to shifting and displacement of pilings.
Step 4: Building the Substructure once your pilings have been driven you begin on the substructure. Braces are placed between pairs of pilings as required by code. When you are in an area prone to flooding, rapid flowing water, or where depth of water at normal low tide exceeds8 feet, transverse bracing also known as x bracing is used. A board is then attached on each side of the piling running parallel to the shoreline and is known as a split pile cap. The holes to attach these boards should be predrilled to prevent the wood from splitting and be faceted in place with a galvanized or stainless steel bolt, a nut, and two flat washers (placed at bolt headland nut end). Then it is time to fasten on stringers or also known as deck runners. Most marine contractors use 8 foot boards which only allow a foot of overhang in which the next stringer is toe nail bolted to.

The Southern Pine Timber Association sponsored a seminar in Annapolis at which recommendations were made for marine applications. LeRoy Holt of Porpoise Cove Marina attended and remembers the following highlights. “The Associations plans require that instead of using 8 foot boards in-between the 7 foot spaced pilings; you use 10 foot boards. With the extra 3 feet of length, it allows a foot and a half of overhang to fasten (bolt) to the next stringer creating a sturdier substructure. It presents itself as a more solid form and can withstand the hydraulic wave action strong storms bring. Building to these specifications requires 10through bolts at each set of pilings. Typical builds have but 2 bolts and nails”

Replacing decking boards or refastening loose ones is a cheap fix compared to losing whole sections of your dock. When building or rebuilding, keep in mind these suggestions. The substructure is the most costly part of dock building but if done right should offer many years of enjoyment… whether threatened by storm or not.

Step 5: Laying the Decking With the substructure in place you then begin to lay the deck boards. The deck boards should be specified and ordered in even 2 foot increments ( 4’, 6’, 8’). The” Rule of Thumb” is decking should be installed bark side up and to avoid cupping it shouldn’t be more than 8 inches in width. Stainless steel screws are superior holding power but may be substituted with stainless steel or galvanized ring or spiral shank nails. After the decking is installed, sealing your dock with a water resistant or other form of wood protectant can help prevent its decay.