Selecting Appropriate Exterior Materials for Your Historic Building | Wisconsin Historical Society

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Selecting Appropriate Exterior Materials for Your Historic Building

Selecting Appropriate Exterior Materials for Your Historic Building | Wisconsin Historical Society

If the exterior materials on your historic house or building are damaged, you will be faced with two choices: repair or replacement of the damaged element. In keeping with historic preservation best practices, you should choose to repair an element whenever possible. If repair is not possible, your next best option is “in-kind” replacement. In-kind replacement means that you replace the original element with a product of a similar shape, texture, size, material and appearance. Some repair and replacement options for common exterior elements are discussed below.

Wood Siding and Trim

The original wood materials on your house or building can last for a long time if you regularly maintain them (prime and paint) and repair them when necessary. The best preservation practice for wood elements is always to keep your original wood features and repair your wood trim elements and wood siding when necessary.

If you must replace some original wood elements, you will find that most of the exterior wood materials on your house or building are still available today. These materials may be available as either as salvaged or new wood. It is never a good practice to replace original wood elements with plastic trim, decking or siding for these three reasons:

  • These substitute materials can negatively alter the historic appearance of your house or building.
  • These products are environmentally unsound because they are made with oil and/or polyvinyl chloride (PVC).
  • These products are unsustainable because they break down when exposed to ultraviolet (UV) light.

Replacement Siding

Two common replacement materials for original wood siding are cement board and vinyl. These two products do not make good replacement siding for several reasons:

  • Cement board siding. Cement board siding is similar in appearance to wood siding and may be appropriate in some circumstances as a siding material on a new outbuilding, such as a garage. However, it is not a good substitute for original wood siding due to its surface texture. Cement board siding often has an embossed wood grain to simulate a rough-sawn look that does not match the smooth appearance of original wood siding. It is possible to find cement board siding with a smooth surface, but it will never look quite the same as the original wood. Because wood siding has different thicknesses, the depth of cement board siding is different than original wood siding and produces a different shadow, which makes the cement board siding look artificially uniform. 
  • Vinyl siding. One of the most common types of replacement siding today is PVC, or vinyl.  There are many reasons why vinyl is not a good replacement siding:
    1. The maximum lifespan of vinyl is 15 to 20 years before it becomes brittle from exposure to UV light. 
    2. Vinyl siding will fade in time and no longer match the color of your original siding.
    3. When vinyl burns, it releases a poisonous gas that can harm or kill people, amplifying the risks of a house fire.
    4. Vinyl siding is always installed on backer board. This insulation board must be installed over the original siding to create a flat surface for the vinyl siding. This extra layer over the original siding can trap moisture from rain as well as water vapor that is generated in the interior of the structure. This trapped moisture can damage the bottom one-third of the original wood siding, creating an environment that is more vulnerable to termites, carpenter ants and mold. 

Porches

Your original wood porch may contain several components, including the flooring, columns and decorative trim work.  

  • Flooring. Your original porch floors are most likely smooth surfaced 3-1/4-inch-wide x 3/4-inch-thick tongue and grooved (T&G) fir or pine wood that is primed and painted. Modern plastic- and resin-based T&G floors have an embossed wood grain and cannot be painted.  Because of these characteristics, none of these products would be considered an in-kind replacement for your original wood porch flooring. Many other alternative porch flooring products are not T&G, so they are installed with a butt joint. Any replacement porch flooring you choose should be T&G like your original flooring.
  • Columns. If you must replace original porch columns, you will find that structural, exterior-grade wood columns are still available and cost-competitive with their synthetic counterparts. They are also available in a wider selection of styles to match your original wood columns. Synthetic plastic, aluminum, fiberglass and resin-based columns are available in a variety of styles. Among the synthetic options, fiberglass columns hold paint the best and look the most like wood columns. Be sure the fiberglass columns you use mimic the style of your original columns.
  • Decorative elements. Your best approach with your decorative porch elements is to repair them. If one of your porch elements is deteriorated beyond repair, you should be able to have a replica made based on the original design. You should only add a decorative element that is an exact reproduction of your original element. Although plastic, aluminum and fiberglass elements like brackets, corbels and gingerbread are available for porches and eaves, none of these generic elements will replicate your original wood elements. If you add these decorative elements to your porch or eave, you will create a false sense of history.

Original Exterior Stucco

Your original stucco can last for several centuries if you maintain and repair it. Repair is always the best option. If a large section or the entire stucco coating on the outside of your house or building has failed, you should replace it with three coats of real stucco in the same manner the original stucco was installed. Stucco is a cement-based coating that is still readily available in Wisconsin. Masons are still able to perform this work at a competitive cost with synthetic stucco application.                                      

Neither of the two primary substitute products for original stucco will match your original stucco. In addition, their installation cost per square foot is similar to real stucco. These products are cement board panels and synthetic stucco.

  • Cement board panels. Cement board panels are manufactured with cement and other binders to create large panels that range from 3 x 5 feet to 4 x 8 feet. Cement board panels must be nailed or screwed onto the wall, which creates multiple breaches in the panel surface where water can penetrate. Because cement boards are panels, it is impossible to press them together on a large wall without revealing the seams between the panels. You might find it difficult to recreate the texture of your original stucco with cement board panels, because only a few texture options are available.
  • Synthetic stucco. Synthetic stucco is known as an exterior insulation finishing system or EIFS. EIFS is essentially a foam insulation board attached to the wall and coated with one coat of a synthetic product to replicate the look of stucco. The foam board is attached to the wall with a fiberglass mesh embedded onto the insulation board. Water penetration behind the foam-based insulation board has been an issue with this product since its introduction. Because EIFS is vulnerable to moisture damage and cannot match the heavier textures common with many traditional stucco finishes, EIFS is not a good substitute to replace your traditional stucco.

Masonry Exteriors

Your original brick or stone exterior can last for several centuries if you maintain and repair it. You should only replace bricks and stones that have been structurally compromised. If your original masonry has a major failure, the most appropriate treatment would be to disassemble and reassemble the original masonry material.

If you need to replace any of your bricks or stones, you should choose replacement bricks or stones that match your originals. Replacement bricks should match the original in size, color, texture and strength. The replacement mortar is equally important. Have your original mortar tested so the new mortar matches its color, texture, composition and strength. If your replacement mortar is stronger than the original bricks, it could cause severe damage to the adjacent bricks. Replacement stones should match in color, size, shape and texture to the original stones. Stone is still being quarried and is readily available.

A variety of synthetic bricks and stones are available on the market today. Large panels of plastic siding with brick embossed onto the surface are available, but these synthetic reproductions will not match your historic house or building.