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by Paul Fisette – © 1997

There are other choices for exterior trim besides solid wood, but understanding how different materials perform and knowing their limitations is the key to satisfaction.

OK. So we all want to use clear, vertical grain, all heartwood western red cedar or redwood for our exterior trim. This material is a time-proven warrior, successfully protecting homes for centuries. It resists decay, remains stable, holds paint well and works easily. But recently, the supply of these materials has been strained and prices have become budget-busters for many projects.

Perhaps just as popular as cedar and redwood is solid wood trim made from other locally available species. Solid wood is a familiar material and many builders will use nothing else. Lumber yards who sell to pro builders report that 90% of the trim they sell is solid wood, once you eliminate vinyl from the mix. But high-grade trim material of any species is getting pricey. Builders complain that the grades are slipping. That the “good stuff” is getting harder to find.

The apprenticeship method of learning still found in the building trades encourages the use of conventional materials. The adoption of new materials and applications is slow to develop. However, builders are moving away from solid wood trim. Builders are discovering options: finger jointed wood (primarily red cedar, redwood, pine and fir); laminated veneer lumber (LVL); hardboard or medium density fiberboard (MDF); and fiber-cement products.

There was, until very recently, another promising trim product available to builders. Louisiana Pacific (L.P.) manufactured and distributed a paper-overlay oriented strand board (osb) product called Inner Seal ® Trim and Fascia. Amidst a squall of reported failures involving Inner Seal ® siding products and a resulting class-action suit against L.P., the trim and soffit products were pulled from the market. A company spokesperson in the Conroe, Texas plant where Inner Seal ® siding products are manufactured, defends the product as a good idea and a good product, indicating that L.P. yanked the trim line only because it was loosing money. The antiquated, continuous-press mill used to make the trim products is blamed for the loss.

As we move away from the tried-and-true toward new products and new technologies, we must remember there is no panacea. There is a price to pay. Some products are difficult to install because they are unfamiliar. Other products are made of materials that require fussy installation to provide long, durable service. Others closely resemble their solid-wood cousins but behave differently. The products reviewed in this article cover a broad range of performance and price. They all require a shift in attitude, but not a drop in performance.

Finger Jointed Wood

Of all exterior trim options, finger jointed material is most readily accepted by builders. It is welcomed as a less- expensive alternative to solid wood even in the conservative Northeast. “The Northeast is one of our hottest markets,” says Keith Kersell, manager of sales and technical services, Pacific Lumber Company (PALCO), Scotia, CA. Keith sees the heaviest demand for finger jointed exterior trim in New England, California, the Gulf States, and the Eastern Seaboard.

Of all exterior trim options, finger jointed material is most readily accepted by builders. It is welcomed as a less- expensive alternative to solid wood even in the conservative Northeast. “The Northeast is one of our hottest markets,” says Keith Kersell, manager of sales and technical services, Pacific Lumber Company (PALCO), Scotia, CA. Keith sees the heaviest demand for finger jointed exterior trim in New England, California, the Gulf States, and the Eastern Seaboard.

Finger jointed wood has a lot going for it. It is a more efficient use of wood fiber. Short high-grade lengths of wood are extracted form otherwise low-grade lumber and reconstituted into long, straight, clear pieces of trim. Exterior weather-resistant glues like melamine-urea or phenolic resin are used to bond the short lengths together to endure exposed conditions. And as far as labor goes, there is no learning curve. It is installed just like solid wood.

Trim stock is available in virtually all species and profiles. Most popular is 1- and 5/4- inch trim that is 4″ – 12″ wide. The wider widths like 10’s and 12’s are often created by edge-gluing several narrower widths together. Edge-gluing is done at the producing mill’s option. When you order finger jointed trim at the lumber yard, you buy a glued product – period. The mill assembles the trim boards according to the widths available during the production run. If they have narrow widths available, then you get edge-glued trim boards. Sixteen-foot lengths are standard fare, but finger jointed trim is readily available in lengths up to 24 feet. Long lengths and 5/4-inch thickness are especially desirable for corner board applications where unbroken lengths and deep returns for siding are called for.

Finger jointed material comes in several grades: clear vertical grain all-heart; clear vertical grain (sapwood present); clear flat grain all-heart or clear flat grain (with sapwood). The best choice of course is clear, vertical grain all-heartwood.

Only heartwood is naturally resistant to decay. And vertical grain material holds paint much better than flat grain material because it is more stable. It shrinks and swells less across its face and has less grain-raising than flat-sawn lumber. As wood moves (shrinks and swells) under a coating of paint, it stresses the bond between the paint and the wood. Ultimately the film of paint is sheared from the surface of the wood. Builders often think that they are going to get vertical-grain performance form flat-grain material as long as it is clear. This is just not realistic. It is getting harder and harder to get vertical-grain material because the size of available trees are getting smaller, but specify vertical grain whenever you can get it.

Finger jointed trim is not without its problems. It makes many builders nervous. Steve Ferrari, Project Manger, Kohl Construction in Hadley, MA is a typical example. Kohl construction is a progressive-minded company that readily embraces new technology. Kohl uses all the latest products in their high-end, high-quality homes. But Ferrari is quick to say, “We are reluctant to use a finger jointed product outdoors.” Builders like Ferrari balk because of horror stories they hear about finger-jointed trim. Stories that tell of finger jointed brick molding literally falling apart after a few years of exposure. And other stories where finger joints have telegraphed through the finish coating of paint.

While tales of woe sift from the field, finger jointed trim still holds promise. Most problems lie in the fact that it looks just like solid wood, but it behaves differently. It is a different material. Consider that you are gluing two different pieces of wood together when you form a finger joint. Even if these two pieces of wood were harvested from the same tree, and exposed to precisely the same moisture conditions during manufacturing, it is unlikely that they will have the exact same grain orientation. Therefore, if exposed to moisture variation in service, each piece will shrink and swell differently, stressing the joint. You will at least “see” the joint if the material is not well-protected. Severe exposure to moisture cycling may eventually cause the joint to fail. This is the basic undoing of finger jointed trim. It requires special care! Finger jointed trim can and does work well when it is specified and handled correctly.

  • specify vertical grain material (heartwood of durable species best)
  • specify exterior-exposure adhesive in joints
  • factory or field-apply oil-base prime coat on all surfaces.
  • use 2 coats of 100% acrylic latex paint for top coats (do not use stains)
  • maintain protective coating on regular basis
  • carefully detail architectural elements to minimize exposure

Laminated Veneer Lumber (LVL)

The manufacturers of engineered wood have expanded their vision. You can now buy laminated veneer lumber (LVL) exterior trim. LVL is made by the parallel lamination of veneers into thicknesses desired for a given application. And just as the first applications of structural LVL were inspired by rising costs and shortages of high-grade lumber; the development of LVL trim is driven by rising costs and reduced supplies of high-grade appearance-grade material. South Coast Lumber Company in Brookings, OR manufactures an LVL trim product called Clear Lam.

South Coast LVL is made of Douglas-fir core-veneers and alder face-veneers. The layup is glued with a phenolic-based exterior glue and sprayed with a preservative to protect the product in the field. The face that is intended to be exposed to the weather is overlayed with a phenolic-based MDO that is about 20/1000″ thick (MDO or medium density overlay indicates that the overlay sheet is 20 % resin solids by weight). As the 48-inch wide LVL sheets come out of the press, they are gang-ripped and precision sanded to widths usable as fascia, soffit and other trim components. Once the individual pieces of trim have been sized, they are fully coated with an elastomeric edge coating and primer. All traces of veneer edge-grain is masked.

Clear Lam is actually a second generation LVL trim product. Their first product, clear trim , did not have an MDO face. Ron Rutherford, South Coast Lumber’s Sales Manager indicates, “The reason we have gone to a paper face is because we saw a lot of face checking in the product we made without the overlay.” Field conditions can be harsh. You can not easily control the amount of heat and moisture that these products are exposed to. So South Coast improved its offering. Rutherford reports, “The MDO facing eliminated the only problem expressed by contractors about our product.”

Clear Lam is stocked by distributors around the country. The 1-inch and 5/4-inch thick material in widths (in 2″ increments) from 4-inches to 12-inches is readily available. Sixteen and twenty foot lengths are standard. But if you schedule your order with a 3-week lead time, LVL trim can be ordered from the factory in thicknesses that range from 5/8″ to 1 1/4″, widths up to 48-inches and lengths up to 24-feet.

The list of benefits are long: It is easy to cut, nail and install; it is durable; it paints well; is available in long lengths and a variety of widths; has no knots or cross-grain; and is dimensionally stable. So where is the catch you ask? I don’t really have much bad news except that it is a little pricey.

The builders I spoke with like the stuff. Steve Greenwell, owner of Renaissance Builders in Turners Falls, MA sums up the feelings of many when he says,”We have used quite a bit of the LVL trim and we have had great luck. It stays together and paints well.” Greenwell has used it for fascia, corner boards, window surrounds and has had only 1 bad piece. However, builders disagree with the dealers contention that stocking only 16-foot lengths is a waste-saving measure. This decision creates waste. Greenwell offers, “If dealers think they are saving waste, let them come visit my shop and I’ll show them a bin full of 6-footers.” The question: if you build a cape or ranch with 9’6″ corner boards, what do you do with the other 6’6″? Dealers should stock these products in at least 2 lengths, maybe 10-footers and 16-footers.

Often, builders combine LVL fascia and rake trim with MDO plywood soffits. Half-inch thick MDO plywood costs around $35/sheet and 48″-wide sheets are stock items in all lumber yards. MDO has a long and successful track record for exterior painted surfaces. It is regularly used by highway departments for painted road signs.

Hardboard Trim

There are currently 4 manufacturers of hardboard trim in the United States: Temple Inland, Georgia Pacific, ABTco, and Forestex Company. All refer to their trim lines as (and would like you to start calling it) engineered wood. Each company’s fiberboard is made in roughly the same way. Hardwood chips are heated with steam and hot water and then passed through 2 rotating discs to create the fiber that is eventually pressed into board stock. An interesting thing happens during this process. When the wood fibers that were sheared apart are hot-pressed into boards, lignin normally found in wood cells begins to flow. In a sense the wood fibers are coated by their own lignin. Lignin is a naturally-occuring “adhesive” that holds wood together. Brown rot fungus does not attack lignin. And many scientists believe that it is this fact that causes hardboard to be a little more resistant to decay than some untreated species like spruce, pine and fir.

There are many similarities among the fiberboard products sold to builders. Hardboard trim is readily available in all regions of the country. All hardboard trim products weigh about the same, around 50 pounds per cubic foot. This is about twice as heavy as solid redwood. Hardboard trim products are available in 1- and 5/4- inch thickness, 4″ – 12″ widths and 16-foot lengths. Manufacturers offer 7/16-inch thick soffit material too. The trim is made with an exterior-grade binder and usually comes in smooth and wood-figured textures. The motivating force for developing these products is cost and availability of high-grade solid wood.

TrimCraft ®, manufactured by Temple-Inland Forest Products, Corp., Dibol, TX, was introduced 4 years ago. Product manager, Gary Martz, claims, “Market acceptance has absolutely blossomed.” TrimCraft ® is not overlayed with an MDO or any kind of facing. The material is homogeneous throughout its cross section. It is a reversible product: smooth on one side and textured to look like cedar on the other side. Temple laminates 2 pieces of hardboard together to create a 1-or 5/4-inch thick trim product which is sold for fascia, rakes or corner boards. TrimCraft ® comes factory primed on all surfaces.

ProTrim ® trimboard is manufactured by ABTco, Inc., Roaring River, NC. The company changed hands in October of 1992. Its name changed from Abitibi-Price to ABTco, but the product is exactly the same. ProTrim ® is similar to Temple Inland’s product is all respects but one: ProTrim ® is faced with a paper overlay they call their “fusion finish”. The overlay is a newspaper-quality paper that is bonded with the addition of linseed oil. “The wood fiber and paper become one.”, according to Michael Donaldson, ABTco’s manager of product design. Donaldson claims that ProTrim ® paints better because of this process. And even the competition agrees. Gib Landis, sales manager for Georgia Pacific says,”They have perhaps the best surface in the business. It paints like a piece of glass.” But Landis is quick to add that there is more to performance than paintability. He feels G.P.”s products are best because “They paint nicely, and are unusually resistant to rot.”

PrimeTrim ® , an unfaced hardboard trim product manufactured by Georgia Pacific, Atlanta, GA, comes primed on its face and two edges. It is not back-primed. PrimeTrim ® has been tested and its resistance to decay has been measured by the Wood Products Laboratory at Mississippi State University. While it is still a mystery why — G.P.’s PrimeTrim ® scored extremely well. It proved to be just slightly less resistant than cedar lumber siding and slightly more resistant than redwood lumber siding when tested according to ASTM D-2017. In this test , wood samples are exposed to rot fungus, put in an incubator and the weight-loss due to rot is measured. Other hardboard manufacturers do not make similar claims.

Forestrim ® , another unfaced fiberboard trim product, is the new kid on the block. Forestex in Forest Grove, OR introduced Forestrim ® just 1 year ago. At this time it comes only in a 5/8-inch thickness, but the company is experimenting with a 1-inch thick product and expects to have it on-line soon. Trim boards that are 3 1/2-inches wide are readily available and other widths can be special ordered.

Each of the manufacturers I talked with expressed concern over the reputation hardboard siding seems to have developed among builders. Many builders I know (myself included) have had problems using hardboard siding. Thickness-swell is a problem. Wood fibers are compressed in the hot-press when the boards are made. Some of this compression stress is relieved over time. This causes the swelling that is observed around nail heads and at the ends of some boards. Hardboard is more likely to absorb moisture and swell where unprotected fibers are exposed to weather. The forces associated with thickness swell are so great that they cause paint coatings to fail along the edges of boards. Water enters cracks and unprotected penetrations (like over-driven nails) in the paint surface accelerating the degrade process. Even if the claims of rot-resistance are accurate, softening, swelling and delamination of fiberboard is an undeniable concern.

Buckling can be a problem too. As we go from solid wood to hardboard during the manufacturing process, we tear down the grain structure of wood, randomize the fiber direction and put it back together as a homogeneous material. The low longitudinal expansion of solid wood is averaged out with the higher tangential and radial potentials. As a result, hardboard shrinks and swells more along its length than solid wood. But manufacturers blame improper application, detailing and maintenance for swelling and buckling problems.

You should flush-nail this product with corrosion-resistant nails. Over-driven nails must be sealed with a paintable caulk. Butt joints must have a 1/8-inch gap that is filled with a flexible caulk. Edges like those where corner boards are joined should not be mitered. All surfaces (face, nail heads and cut edges) should be sealed with 2 coats of acrylic latex paint. Do not install hardboard in direct contact with concrete. Never nail from both ends of a board toward the middle. And hardboard should be reprimed prior to finishing if it is left unpainted for longer than 60 days. If you follow these rules, manufacturers claim you won’t have swelling or buckling problems. The problem then becomes a maintenance issue.

Temple Inland’s Martz says that their TrimCraft product can go 5 to 10 years between painting as long as the base coat of paint is applied correctly. By all accounts, to expect this kind of paint performance on any material is truly optimistic. But good flashing, smart detailing and frequent painting should keep customers happy with hardboard trim products.

Installing hardboard trim takes some getting used to. Steve Ferrari says, “I love it, but my carpenters hate it.” Steve, like many builders, has had very good luck using these products. He is fussy with the details. And the houses I visited looked perfect after 4 years of service. However, his carpenters find it difficult to nail. Getting the right setting with nail guns is tricky. And they have patched and sanded quite a few nail heads to make their jobs top-shelf. Overall, it takes a little more to time to install than conventional wood trim. But for his money, Ferrari thinks it is a good deal.


Fiber-cement trim has a unique appeal: once you install it, it’s there forever. And as one builder said, “It is not what it does on the wall, it is what it doesn’t do.” Fiber-cement composite is a mixture of wood-fiber reinforcement (under 10%), Portland cement and sand. It is durable, dimensionally stable, fire resistant, and immune to the effects of insects, water, and sunlight.

There are two players in the autoclaved fiber-cement market. James Hardie Building Products, Inc., Fontana, CA and Eternit, Inc., Blandon, PA. James Hardi has been manufacturing fiber-cement for over 100 years in Australia. They offer a full compliment of fiber-cement building products including roofing, siding, trim and underlayment. While Eternit and Hardi manufacture very similar composite trim materials, it is Hardi that is wooing the light-frame construction market. James Hardi manufactures HardiTrim ® , a 7/16-inch thick trim product that is manufactured in 4-, 6-, 8-, and 12-inch widths. It is sold in 12-foot lengths. They also manufacture 1/4-inch thick HardiSoffit ® in 16-, 24-, 36- and 48- inch widths and 8-, 9- and 10-foot lengths. Eternet, on the other hand, makes several products, but all are sold in 4’x8′ (or larger) panel format, not user-friendly!

HardiTrim ® is a new product and all sizes are not yet available in all markets. Furman Lumber’s Houston branch is Hardi’s largest distributor and offers all sizes to the Southwestern market. The product should be rolled out in Northern markets within a year. With a 50-year transferable warranty and at 60% the cost of solid wood it is expected to become a popular offering for Furman.

The first thing builders say when told about a fiber-cement product is, I don’t want to have to drill every nail hole. “You won’t have to pre-drill”, says Wes Webb, General Manager for Furman’s Houston branch but, “There is a little bit of learning to do with this product.”

A couple of Webb’s major builders have switched to HardiTrimª and while they like the performance that is promised, they find it more difficult to work with. They use regular galvanized nails to fasten it and recommend using a 2″x4″ sub-fascia to provide straight, solid nailing. Fiber-cement is dense(80 psf) and hard. Straight and miter cuts are made using a circular saw equipped with a carbide-tip blade. The blade is usually thrown away at the end of the job. A diamond tip blade lasts much longer, but is slower and its cuts are not as clean. Because the trim is only 7/16-inch thick corner boards must be built out with 1/2-thick wood backing. All fiber-cement boards should be field trimmed because factory ends are not reliable. Fiber-cement does not have nail-holding power of its own, so solid nail-backing must be provided behind all butt-joint and miter connections.

Paint lasts a very long time on fiber-cement. Since the material is so moisture resistant and stable, stress does not build under the coating as it does with wood products. In fact, Lee Brunner, N.E. Sales manager for James Hardi reports that PPG and Olympic offer a 15-year warranty for their factory-applied finish on Hardi products. Some fiber-cement products need an alkali resistant paint, but Hardi recommends a regular acrylic-latex.

Working with fiber-cement is different than working with wood. It is not only more difficult to nail and cut, it is a dusty material to machine. Health concerns laid out in the Fiber-Cement Material Safety Data Sheet should be recognized and respected. These products contain silica that is bonded securely in place in its manufactured form. But dust masks should be worn while cutting or drilling. Breathing silica dust can cause silicosis, a non-cancerous lung disease.

Last Word

Working with new materials requires patience and an open mind. Everything doesn’t work as easily as wood — to a large extent because we are so familiar with wood. We were trained to use wood and our tool boxes are filled with tools made to work wood. Builders who have used pine trim for years are satisfied with its performance, yet pine is not a naturally durable wood. It rots if it is not protected by careful detailing and a good coating of paint. Pine has cross-grain and knots. It shrinks, swells and degrades when exposed to rain and sunlight. I love working with wood and it is always my immediate first choice. But other materials can work as well if they are treated with the understanding that will make them work.

Cost Comparisons

grade/product species size price/lin.ft.
A & better western red cedar 1″ x 6″ 1.75
select clear eastern white pine 1″ x 6″ 1.25
#2 common eastern white pine 1″ x 6″ 0.55
hardboard assorted hardwood 1″ x 6″ 0.75
LVL Douglas-fir 1″ x 6″ 1.35
fiber-cement N/A 7/16″ x 6″ 0.45
finger jointed western red cedar 1″ x 6″ 1.15


Hardboard Products

American Hardboard Assoc., 520 N. Hicks Rd., Palatine, IL 60067 312-934-8800
ABTco Building Products Corp., P.O.Box 98, Hwy. 268, Roaring River, NC 28669 800-334-3551

Forestex, P.O.Box 68, Forest Grove, OR 97116 503-357-2131 Georgia Pacific, P.O.Box 105605, Atlanta, GA 30348 404-521-4000 or 800-447-2882

Snavely Forest Products, P.O.Box 310, 53 Bannard St, Freehold, NJ 07728 908-462-2323 or 800-233-0118 (distributes LVL Clear Lam and ABTco)

Temple-Inland Forest Products, Corp., P.O.Drawer N, Diboll, TX 75941 409-829-5511 or 800-231-6060

LVL Trim

Snavely Forest Products (see above)

South Coast Lumber Company, 815 Railroad Ave., P.O.Box 670, Brookings, OR 97415 503-469-2127


Eternit, Excelsior Industrial Park, P.O.Box 679, Blandon, PA 19510-0679 610-926-010

Furman Lumber, Inc., P.O.Box 130, Nutting Lake, MA 01865 800-843-9663
—— Houston Branch 800-392-3942

James Hardie Building Products, Inc., 10901 Elm Avenue, Fontana, CA 92337 800-942-7343

Fingerjointed Wood

Pacific Lumber Company (PALCO), Main St., P.O.Box 37, Scotia, CA 95565 707-764-2222