All things fade then fail with time. Building facades are no different. Over the years, condos have had their exteriors clad with a wide range of materials including vinyl, wood, metal, EFIS, brick, stone, and engineered composites. But after 30 or 40 years their age begins to show in the form of water infiltration; thermal distortion; color fading; wood rot; mechanical damage and it becomes obvious to the unit owners it is time for a change and the hard decision to reside the façade.
The decision becomes even more complicated when presented with all the possible product alternatives to choose from. Sometimes the choice is forced upon the community due to monetary restraints. Vinyl is the most economical siding while some communities with brick or stone facades conclude repointing or other weatherproofing process is the only answer. However, for the balance of condominium exteriors an excellent choice for a façade replacement would be fiber cement.
Fiber cement building materials are in more than 20% of all new condominium construction across the country. The reasons are simple – it looks like wood but is termite-resistant, water-resistant, non-combustible, can resist hurricane force winds (when face-nailed) and warranted to last from 15 to 50 years.
Fiber cement siding is composed of cement, sand and cellulose fiber that has been autoclaved (cured with pressurized steam) to increase its strength and dimensional stability. While current manufacturing processes do not allow for the reprocessing of fiber cement siding, the manufacture of the material itself utilizes wood chips reclaimed from wood processing (the cellulose). When combined with the long lifespan of the siding, the integrated wood fiber qualifies the material for “green” points under several different programs.
Painted finishes on fiber cement are far more durable than on wood, due to the uniformity and high density of the product and because fiber cement does not absorb water as readily as wood. It can be repainted in the future.
There are several manufacturers of fiber cement siding, including WeatherBoardsTM manufactured by CertainTeed and WeatherSideTM manufactured by GAF. One of the better known is James Hardie Building Products, manufacturers of Hardiplank®, whose trade name has become synonymous with the product. Allura fiber cement siding is also a good choice.
Fiber cement siding is molded to resemble wood products. Applications are used in place of conventional clapboards, shingles, and vertical siding. Although flat and embossed wood grain lap siding are the most common patterns, manufacturers are introducing a greater selection of alternate designs such as those that resemble stone or shingles.
Products are manufactured as planks or boards. Trim materials such as soffits are also available. Trim should be installed at the corners and around windows to guard against leaks. When fiber cement materials are not available, vinyl should be used as aluminum trim will react adversely with the siding’s ingredients.
Products are available unfinished or pre-primed. The use of pre-primed materials will ensure coverage and improve installation efficiency. Ends should be primed in the field when cut.
These siding materials are offered pre-finished by the manufacturer in a variety of architectural matte colors. Although providing a good opaque painted surface, there are at least three drawbacks to specifying pre-finished siding. One is the potential problem of slightly varying color between dye lots. A second issue is matching the recommended touch-up at cut ends. The third is that recommended caulk joints become difficult to disguise. Because the manufacturers demand a premium for pre-finished siding, there is little economic incentive compared with a field-painted building. Field painting also offers the advantages of providing the owner and architect with a limitless color palette.
Although greater lengths may be special ordered at premium cost, standard stock order length is 12 linear feet for both siding and trim. Joint making will therefore generally constitute a greater labor factor than is usually the case with wood or other synthetic materials available at greater lengths.
Fiber cement siding is easier to install than other types of siding but paying attention to the manufacturer’s specifications is critical. That may not always be easy since these specifications can sometimes be vague. Language such as “leave appropriate gap between planks and trim” and “install planks in moderate contact” can leave installers scratching their heads. A licensed engineer or architect is recommended to prepare the project specifications. Hire only a competent contractor familiar with fiber cement siding and insist on good quality control and installation monitoring.
Cost is always going to be a driving factor in condo community decision making. The challenge is to understand what the true cost will be. Vinyl siding is the least expensive up-front cost, but the full life-cycle cost should also be considered. Fiber cement siding’s predicted useful life of 50 years will not only be a good financial investment, but its superior appearance will provide a quality-of-life benefit for many years to come.
Written by Jack Carr, P.E., R.S., LEED-AP, Senior Consultant Criterium Engineers
Published in Condo Media