Deck & Fence Questions Answered

Over the last several years, the HIR staff has been asked and has answered a multitude of questions regarding home improvement, maintenance and around-the-house repairs. Here’s a look back at some of the different deck and fencing topics and tips we’ve covered for our readers.

What’s the best way to clean mold off a wood fence?

Bleach does a good job of cleaning off mold and mildew, but the type bleach makes a difference. Chlorine bleach does a fine job removing superficial mold, but it’s not as effective killing mold on porous surfaces such as outdoor wood, because the mold’s enzyme roots grow inside the pores. Chlorine bleach can’t penetrate the porous material due to its ionic structure, so the mold problem will likely return. Chlorine bleach also damages the lignin in the wood, which is what bonds the wood fibers together, and this will make it more prone to aging and splintering along the surface.

An alternative is to use oxygen bleach. An ingredient found in laundry detergent, oxygen bleach cleans fabrics without disrupting the color or damaging the material. It can be

combined with water, applied to the wood and allowed to soak for 10 or 15 minutes,

then it can be scrubbed and rinsed off with a garden hose. Oxygen bleach cleans the

wood without damaging the fibers or harming the surrounding vegetation, so there’s no

need to use drop cloths for protection.

If I want to build a circular shaped deck, how do I bend the board along the edge?

On most decks, the outer band or rim joist is made of the same lumber as the other joists, which means it doesn’t bend. To create a curved rim joist, a popular technique involves layering thin sheets of weather-resistant plywood onto the framing. These sheets are installed one layer at a time using clamps, adhesives, and fasteners, building up to a thicker, structural board through this lamination process. 

Composite deck fascia is made from the same material as composite deck boards, but it is thinner, which makes it flexible. This flexibility allows composite deck fascia to bend along its length, making it suitable for wrapping around curved decks to match the deck boards. An unusually tight radius might require the application of heat to the fascia board to increase its flexibility.  

I’m trying to determine board sizes and beam spans for a backyard deck. Can you clarify the meaning of “live” versus “dead” loads when designing the deck frame?

The concept of “load” in structural design generally falls into two major categories: dead loads and live loads, which are forces that cause stress or displacement to the structure and risk its failure.

The dead load of a structure comprises its completed weight before it goes into service. The floors, walls, roof, columns, stairs, permanent equipment and any fixed decor constitute a static load that normally doesn’t change over the life of the structure. In other words, the dead load is calculated before the structure takes on additional loads from occupancy or use (including the weight and movement of any people and components).

Live loads refer to the dynamic forces from occupancy and intended use. They represent the forces that can move through the building or act on any particular structural element. These loads include the anticipated weight of people, furniture, appliances, automobiles, moveable equipment and the like.

Because live loads depend on structural strength, it’s critical to know of the exact planned use of the structure—for example, whether the structure is a roof for a pergola or a deck intended to carry the weight of foot traffic.

To pass building code requirements, a structure must also be built to withstand dynamic lateral loads, which can come from wind, snow loads, soil movement and even seismic activity.

If you have doubts about the design of your deck, we suggest you consult a structural

engineer.

Why do deck-building instructions require fastening a ledger board’s lag bolts in a zig-zag pattern rather than a straight line?

The staggered pattern of the lag-screw or through-bolt locations ensures there’s enough wood around and between the fasteners to reduce splitting the ledger board. The recommended pattern also recommends minimum and maximum distances the two rows of fasteners can be spaced apart to achieve maximum holding power while not splitting the wood.