“Stucco” finishes are probably the easiest and most popular method to finish exterior ICF walls. They are fast, cost-effective to apply, and are readily available in an amazing array of colors, textures, and patterns.
Most “stucco” finishes applied to ICF walls are more correctly described as Textured Acrylic Finish Systems (TAFS). PermaCrete, Degussa, Dryvit, and GrailCoat offer specially formulated products for ICFs.
Workers start by going over all the ICF walls with a large rasp. This may be the most time-intensive part of the process. The idea is to roughen the block and remove oxidation, dirt, and other small particles from the foam. Any large gouges or gaps should be filled with aerosol foam and trimmed flush. Exterior framing—such as roof gables and porch columns—need to be covered with rigid foam board. Trim, usually built up from strips of EPS foam, is fastened into place with drywall screws and large nylon washers.
Methods for applying the base coat vary from manufacturer to manufacturer. Most apply the basecoat first, then trowel the mesh into place, although a few recommend mechanically fastening fiberglass mesh to the wall. When the base coat is dry, inspect it for any imperfections. Sometimes, a second coat of base is required.
The trim color is usually applied, textured, and allowed to dry before the crew applies the main color coat. If the trim is a different color than the rest of the building, carefully mask the trim prior to applying the main color.
Finishes applied in the sun dry faster, and probably need to be textured only once, while walls worked in the shade may need two passes for consistent texturing. Don’t be fooled into thinking faster is better. The difference in dry times can affect the finish color, and shadows from scaffolding and planks have been known to leave permanent marks on walls worked in direct sun.
The creative uses of EIFS are not limited to a few simple textures or colors. When applied by trained contractors, they can look like limestone block, antique brick, or even granite. Fossilcrete has gone a step further and made it possible to create cobblestone, flagstone, and even rustic log finishes on ICF structures. The secret is a low slump mix that can be applied up to an inch and a half thick, and can then be stamped, stained, or even hand-carved to achieve the desired finish.
Exterior finishes are the most visible part of any building, residential or commercial. It’s only logical to choose a finish that will compliment the style, quality, and durability of your ICF project. » For the full version, subscribe today!
Nestled high in a mountain valley, this custom ICF home is as durable and unique as the landscape that surrounds it. Built with 12-inch high Greenblock forms, its numerous sweeping radius walls immediately catch your eye. Two of the largest anchor the corners of the structure, rising over 20 feet tall and providing architectural balance to the enormous triple picture windows that flank the front entryway.
Built just below the ridge of a gently sloping hillside, the lot overlooks a lush alpine valley sprinkled with spruce trees and accented by rugged cliffs that jut from the valley floor.
The first floor of the house doubles as a retaining wall for the hill behind it, with as much as 10 feet of the ICF wall below grade. Steel piles will assist in stabilizing the hillside.
ICFs offer an easy solution to many of the challenges of building in mountain regions, where heavy snow loads, extreme cold, and uneven lots present difficulties for traditional construction methods.
Waterproofing below-grade ICF walls is one of the toughest challenges a builder can face. The trick to getting a watertight structure is to use the right materials, applied by an experienced, knowledgeable contractor.
“To waterproof below-grade ICFs, I’d recommend a peel-and-stick membrane,” says Norman Williams, construction support at ICF Builder’s Network. Sheet goods are becoming more common on residential jobs. They offer precise millage and can be applied regardless of the weather. Sheet membranes offer better termite protection as well, and won’t check in the heat, as some spray-ons do.
Be careful of penetrations and seams, the biggest trouble spots with sheet goods. The best advice is to pick a qualified, factory-trained installer that has worked on ICFs before. Some of the most popular sheet membranes are actually drainage systems, and many in the field urge coupling these with a true waterproofing membrane to ensure an impermeable wall. “A dimpled membrane by itself is simply dampproofing,” says Williams.
Makers of dimpled membranes, however, strongly disagree. Dwight Walker, a tech representative at Cosella-Dorken, says, “Our Delta MS has been recognized by the ICC [the International Code Commission] as an approved waterproofing system.”
Walker admits that additional protection is needed for foundations that sit immersed in groundwater, “but in those situations, you’re basically building Noah’s Ark.”
Most residential jobs are waterproofed with spray-on products, despite the advantages sheet goods offer, primarily due to cost concerns. Spray-on coatings can usually be applied more quickly, and with less labor, than any other type of waterproofing. They create a single, seamless coating with no gaps at penetrations. Tie locations are irrelevant, and termination strips are not needed.
Solvent-based products, however, can’t be used. They will dissolve the polystrene on contact—similar to gasoline in a foam cup. Hot-applied systems are equally destructive.
E-Pro Services makes a latex product that solves both problems. It goes on cold, so it won’t melt the foam, and since it is water-based, it can be built up to the required thickness in a single application. It adheres even to oxidized foam.
The most important item to remember when waterproofing ICFs is to do it right the first time. Any voids in the concrete remains hidden behind the ICF blocks, and because of capillary action along block seams and micro-voids at the ties, tracing leaks is extremely invasive—and costly.
“Repairs are a headache,” affirms Williams. “Do it right the first time.”
Infill developments present unique challenges. The lots are usually narrow and the focus is often on affordability. The new homes should match the neighborhood, but prospective buyers will be expecting the amenities to match new construction.
Sunshine and Frederick Tartter, owners of JOY Enterprises, a Reward Walls ICF builder/dealer located in Wappingers Falls, New York, saw the solution in ICFs.
Step #1 was finding the right home design. Sunshine found the 3-bedroom, 2 ½-bath plan, the Ansley, in the Design Basics library of home plans. The home’s rectangular foundation and the fact that nearly all of the second floor walls were stacked over the main floor maximized the efficiency of building with ICFs.
Nine foot ceilings and an island kitchen with large pantry were easily accomodated. A planning center in the breakfast area and a real laundry room with sink were unexpected plusses. Another unexpected design amenity was a computer desk in the second floor hallway.
Using ICFs, the Tartters were able to propose homes offering unmatched performance and affordability. Stronger than conventional framing and with a 2 to 4 hour fire rating, ICFs promised a 15% reduction in homeowners’ insurance. Energy bills would be cut in half. Bothersome traffic noise would be greatly reduced.
As the Tartters have shown, ICF construction should be a top candidate for affordable housing. For their visionary approach to re-defining affordable infill housing, we salute Sunshine and Frederick Tartter.