CHARLESTON, SC (WCBD) – Even as Hurricane Irma’s trek trends to the west, many residents along the Grand Strand and Charleston are preparing their homes and businesses with sand bags.

Sandbags will likely be your first defense should Hurricane Irma bring flooding. To get the benefits of those sandbags you have to use them correctly.

In Charleston, approximately 16,000 sandbags were distributed Thursday, the highest rate in the city’s history. Sand was also made available in Myrtle Beach near the Train Depot for residents who wanted to bring their own bags to prepare.

Although sandbags do not guarantee a watertight seal, they are a proven deterrent to costly water damage, according to the Army Corps of Engineers. Sandbags can be used in front of doorways, roller doors, and brickwork vents.

The first step is using a plastic lining, like a tarp or shower curtain. Tape the plastic to the door frame.

Next, build your sandbag wall. The experts say bags should only be half full. This allows the sand inside the sandbag to mold with the ground or other sandbags when they are stacked, preventing gaps. Fold the bag opening closed, and tie only if necessary.

As you set them down, put the new bag over the tail from the first bag.

On the second row, fill in any cracks by offsetting bags by half the bag length.

Sandbags provide the mass to counter the force of the floodwaters, according to FEMA.

Once you’re done, fold the plastic over the entire wall.

Make sure that you have at least one doorway that you can use to access or exit the building. Do this by building a wall that allows the door to still be opened.

Sandbags can also be placed over shower or bath drains to prevent backflow of water entering.