The exterior finish is a building’s first defense against the weather, and its most visible aspect. Building systems that rely on the exterior finish as the sole weather barrier are susceptible to failure—especially in climates with wind-driven rain or without good drying conditions. The driving forces of wind and other air-pressure factors will force moisture through even the smallest openings. Because of this, siding or curtain wall systems designed around the rain-screen principle are much more effective and durable. This strategy uses a vented exterior finish and a tightly sealed secondary barrier that work together to equalize the pressure on both sides of the exterior finish, taking away the forces that would otherwise drive moisture inwards.
Our SIPs use OSB as exterior sheathing; this is ideal for attaching almost any kind of siding. Siding is intended to be the primary defense against moisture.
We recommend using felt paper rather than a more impermeable building paper or house wrap like Tyvek or Grace Ice and Water Shield. The reason for this is that no weather barrier is perfect, there will always be nail and staple holes at the very least, therefore, small amounts occasionally leak through. This very minor condensation and leakage is not a problem, unless it is prevented from drying out. Felt paper doesn’t impede the drying process, it actually speeds it by absorbing water from the OSB and bringing it to the surface to dry.
In order to deal with the inevitable small amounts of leakage a vented rain screen is essential for the long term success of your building project. A vented rain screen allows air flow to dry out any moisture and equalizes the pressure on both sides of the siding discouraging capillary action.
The rain screen is often simply vertical strapping over a water proof building paper. This works well for siding like clapboards but requires an additional layer of horizontal strapping for nailing shingles. We recommend a simpler solution of Home Slicker or Cedar Breather two products that wrap the building on top of the building paper.
Among the product options:
Recycled-wood-fiber composite siding and trim are more stable than materials made from natural wood, hold paint better, and generally cost less. Some hardboard products have had durability problems when improperly installed or when installed without adequate drying provisions in wet climates.
Fiber-cement siding is very durable, looks like wood when it’s painted, and provides a fire-resistant surface. The wood fibers provide strength, elasticity, and good paint-holding ability.
Locally produced brick and stone are long-lasting, low-maintenance finishes that reduce transportation costs and environmental impacts. Molded cementitious stone replaces the environmental impacts of quarrying and dressing natural stone with the impacts of producing cement.
Shou Sugi Ban – The Traditional Art of Charred Cedar
Shou Sugi Ban is an ancient Japanese exterior siding technique that preserves wood by charring it with fire. Traditionally, Sugi wood, also called Japanese cedar was used. The process involves charring the wood, cooling it, cleaning it, and finishing it with a natural oil. This ancient Japanese technique dates back to the 18th century, and was traditionally used on siding as a natural sealant to protect wood from decay, pests, wind, water, sun, and fire.
Today Shou Sugi Ban is an environmentally friendly way to preserve timber and (paradoxically) make it fire-resistant. Chemical preservatives, paints, and retardants are therefore unnecessary. In addition to exterior uses, the popular technique is now found in interior rooms, furniture, and artwork.
Although time consuming, the final product is not only gorgeous, with its rich, silvery finish; the charred wood also resists fire, rot, insects, and can last up to 80 years.
That’s right — burning timber creates a protective layer over the wood and can preserve it for up to eighty years!