Selectwood Perspectives

How Fiber Cement Evolved

Evolution of Fiber Cement Siding

Wood clapboards have defined the look of traditional New England architecture since colonial times.  Factory priming and finishing of wood clapboards has dramatically improved finish retention and long term maintenance. Still periodic sanding, scraping and repainting is inevitable.

Vinyl siding was the first successful product to challenge wood clapboards in the Northeast market. Vinyl siding has benefits which has contributed to its success with builders and consumers – cost, ease of installation and low maintenance. Vinyl siding now represents 39% of all residential building siding in the U.S. though vinyl siding often does not satisfy the tastes of discerning architects, builders and consumers. Vinyl’s less than authentic appearance created an opportunity for Fiber Cement lap siding as an alternative to wood.

Cementitious siding or Fiber Cement is primarily made from Portland cement mixed with ground sand, cellulose fiber then treated with pressurized steam. The cellulose helps bond the mixture and avoid cracking. As Fiber Cement manufacturing evolved, manufacturers developed more sophisticated formulas. Today, manufacturers can make “green” claims about Fiber Cement due to the recycled material content embodied in various formulas.

 Cellulose Fiber Cement Composite (CFRC) siding products were developed in Australia and Europe and not initially embraced in the U.S. By the late 1980’s Fiber Cement products started to make inroads. In the early 1990’s manufacturing started in the U.S. Production grew from zero to over 1.3 billion square foot per year. By year 2000 Fiber Cement held 6% of the siding market. Today, Fiber Cement occupies over 18% of the residential siding market.

The first areas of the U.S. to embrace Fiber Cement were the South Eastern states. Fiber Cement became popular in the southern U.S. as a superior product in resisting rot and insect degradation. Additionally it is far more fire resistant than wood siding and proved to hold finishes as long or longer than traditional clapboards. As it provided a significantly lower price alternative to high quality wood, the South East building market embraced Fiber Cement.

The traditionalists of the North East were slower to adopt Fiber Cement siding. Even though Fiber Cement is less expensive than wood it is heavy and initially more difficult to work with. Slowly the traditionalists began to recognize that unlike vinyl siding, a home sided with Fiber Cement was hard to differentiate from wood clapboards. Furthermore, when cost and finish retention are considered it is difficult to dismiss Fiber Cement.

Fiber Cements evolution in the Northern markets presented new challenges for manufactures with larger swings in seasonal temperatures and humidity. Fiber Cement naturally expands and contracts under these conditions. Climate changes don’t inherently degrade Fiber Cement but early experiences unveiled certain inherent problems. The surface of Fiber Cement is only slightly permeable but it is up to ten times more permeable on its edges and end cuts. Early installations in freezing climates didn’t recognize the importance of proper painting, caulking and flashing techniques for the long term installation success. Uncoated edges of Fiber Cement when subjected to moisture during freeze thaw cycling can eventually degrade.  Factory finishing wasn’t common in early days and edge protection wasn’t  well understood. Today almost all Fiber Cement siding is supplied with a warrantied factory finish. With proper installation techniques and better finishing systems there is little reason to be concerned in Northern climates.

With Fiber Cement siding we see the following advantages:

  • A resilient material manufactured to closely mimic the look of wood shingles and clapboards.
  • Less expensive than high quality wood clapboards & shingles.
  • Highly durable, with a life expectancy greater than 50 years.
  • Inherently resistant to damage from rot, insects and flame spread.
  • Allows for color changes with minimal surface preparation.

Fiber Cement Manufacturer Updates at Selectwood as of Fall 2011

James Hardie:

James Hardie introduced “The Hardie Zone System” of siding products with “specific performance attributes relative to the climate the home is being built”. James Hardie engineers developed a HZ5 composition of Fiber Cement to achieve the greatest performance in freeze-thaw, snow and ice climates.

This year James Hardie also unveiled the all new HardieShingle Siding System in four foot as well as individual shingles. According to James Hardie the new HardieShingle even better “captures the authentic look of cedar shingles”. Additionally, the Hardie Shingles are formulated in the Hardie Zone System and available in the Hardie Color Plus baked on factory finish with a 15 year warranty.

CertainTeed:

CertainTeed recently announced they reformulated their Fiber Cement products to contain more than 30% pre-consumer recycled material. This formula may help projects gain Leed and NAHB certifications. CertainTeed uses fly ash, a byproduct from coal fired electrical generation plants which would normally go to landfills and utilizes it as part of its Fiber Cement shingle and siding formula.

Other Updates from CertainTeed:

  • FiberTech Sealer/Primer now allows the longest interval (up to 24 months) before final finishing is required.
  • Variable width, straight edge 4' shingle panels in 5" or 7" exposure coming soon.
  • Lighter 12' long perfection shingle panels with 7" exposure with new 7/16" thickness. Easier to handle, faster to install.

All the major Fiber Cement manufacturers seem intent on constantly fine tuning their products and both lap siding and newer shingle products. For Northern builders, todays Fiber Cement products are better factory sealed and better formulated to tolerate freeze – thaw cycles. Even though a Fiber Cement lap siding may not be as effortless and satisfying to install as Western Red Cedar Clapboards, it is a cost effective alternative that's here to stay.