Proper construction techniques will give you the most from your building materials, and cedar planking is no exception. Prized for its beautiful grain and natural resistance to rot and pests, cedar is a top choice for outside structures, such as decks and fences. Spacing your cedar decking correctly will allow the deck to dry more quickly after wet weather and allow room for swelling that may occur because of damp conditions.
Spacing the Boards
Wood is a porous material and as such has a tendency to absorb moisture from the surrounding environment. When this happens the wood can swell, causing problems with joints and fasteners and even doing damage to surrounding pieces. To prevent this, it is recommended that decking boards be placed with a space between the rows ranging from 1/8 to 1/4 inch.
For green material that is fresh and may still have some sap, 1/8 inch spacing is the more desirable of the two. As the sap and moisture dissipate from the material, it will have a natural tendency to shrink. Many times this will cause the gap to widen, leaving what was a 1/8 inch gap at 3/16 or even 1/4 inch. Leaving the gap too wide before the material is properly seasoned can cause the gap to widen further, making it unsightly and even problematic for pedestrians wearing shoes with narrow heels.
Dry material should be spaced a full 1/4 inch apart to prevent damage to the boards as the material absorbs moisture. The gap will naturally close and widen throughout the year as the weather and seasons change.
The space between the ends of boards should always be 1/8 inch. Typically the end cuts will not swell as mush as the sides, which run with the grain.
Spacer Tools You Can Use
Spacing the boards can be done quite simply. For a 1/8 inch space, carry a 16-penny nail that can be stuck between boards to space them apart as they are attached. Keep the lines between the boards as even as possible for the best visual effect.
For a 1/4-inch space, use the thick end of a wood chisel. Place the chisel between the boards and push the board to be attached firmly against the chisel set against the previously attached board.
Plywood pieces, shims and screws also can be used as makeshift spacers. Usually the exact spacing is only critical to the visual effect of the deck. Be careful not to space boards so far apart that they are no longer able to be fastened down securely. A slightly smaller gap is preferable to a weak joint.