Basement waterproofing is probably the toughest issue ICF contractors face.
Below-grade construction presents a long list of challenges: The interlocking edges of the blocks are points where water can penetrate. The surface of the ICF is extremely difficult to adhere to, especially with the construction dust that is usually present. The blocks are often damaged during shipping or erection and must be patched prior to waterproofing. Also, the waterproofing can easily be damaged by the backfill.
Lastly, the ICF wall often includes cold joints, voids in the concrete, and shrinkage of the concrete away from the ICF, all of which offer channels that water can migrate into and through. This is especially true if the water is driven into the wall by hydrostatic pressure.
These factors make it very difficult to identify the source of a leak—and usually, they make the repair of the leaks even more difficult. The point is that with ICF construction, it is extremely important to use a quality waterproofing system and install it properly the first time.
So what exactly constitutes a quality waterproofing system?
A seamless, flexible waterproofing membrane with good adhesion on ICFs.
Detailing materials for cold joints, transitions, and penetrations.
A protection course that resists chemicals, protects from backfill, and guards against root penetration.
A drainage board that relieves hydrostatic pressure.
A footing drain system that effectively directs water to a sump pump or a daylight outlet.
An underslab moisture/vapor barrier that prevents moisture driven through the slab.
Architects, contractors, and building owners should understand that perfectly waterproof ICF foundations and basement are feasible. It simply requires an understanding of the potential problem areas, use of quality materials, good jobsite preparation, and careful application.
Over the last eight years, dimpled sheet waterproofing membranes have been growing in popularity with residential homebuilders.
These “air gap” membranes provide a path for rainwater to be directed to the footing drains at the base of the foundation, instead of being forced into the basement. By providing a drainage path, these sheets diffuse the hydrostatic pressure that affects conventional dampproofing and waterproofing systems.
DELTA MS Clear is a translucent (clear) dimpled waterproofing sheet membrane made specifically for the ICF industry. One main advantage is that the installer can easily see through the membrane to locate the attachment points on the ICF block. Delta MS is approved by the NRC and ICC as a wall waterproofing.
Platon Foundation Protector, manufactured by Armtec, is another popular dimpled sheet. With carbon black as the UV inhibitor, and the patented Speedclip / Speedstrip fastening system, Platon is strong enough to require fastening only along the top edge of the membrane. Its unique double dimple design provides a smooth soil side surface ensuring low drag on the membrane as the back-filled soil settles. Mechanical fastening allows the wall to shift, crack and settle without affecting the membrane or its performance.
Dimpled membranes can be used as protection board for both peel-and-stick or spray-on waterproofing giving “triple protection” to the foundation. The dimpled membrane provides the first line of defense, the air gap drainage plane is the second line, and the peel-and-stick or spray, the final defense.
It is almost impossible to find a leak in an ICF foundation without destroying the foam, so it is critical that the right materials are selected and applied. » Subscribe Now For the Full Story!
Installing Peel-and-Stick Systems
When consistency is important, like it is on below-grade ICF projects, peel-and-stick waterproofing systems are an excellent choice. These flexible waterproofing systems—more accurately called self-adhering, rubberized asphalt sheet membranes—provide a more consistent layer of protection than spray-applied systems, where consistency depends more on the applicator than on the product.
Sheet waterproofing membranes are applied to the form after the concrete cures. If the forms are clean and dry, there is no need to prime the forms before application of the waterproofing membrane. Long exposure to sunlight can create a chalky layer of material on the form surface, which can interfere with adhesion. If this occurs, or if the surface of the form is dirty, excess dirt and dust can be brushed off, and then a water-based primer can be applied. It is important not to use primers—or any other products—containing solvents, as those solvents are extremely aggressive and can dissolve the foam.
Install the membrane by positioning the sheet in place and peeling off the release film. Use heavy hand pressure or a suitable roller to press the membrane firmly against the wall. Install an acrylic sealant and termination bar (wood or metal) at the top of the waterproofing. Protection board should be used as a part of these waterproofing systems, and the area should be back filled as soon as possible.
If installed in the manner described here, sheet membranes provide superior protection while maintaining consistency and control during the application process.
Good concrete consolidation is essential for strong, energy-efficient ICF walls. Ironically, corners and lintels—the areas that need the most strength—are the areas where poor consolidation is most likely to occur.
How much vibration does a wall need, and what is the best way to do it? Every contractor has his preferred option. Several years ago, the Portland Cement Association (PCA) conducted an in-depth study of concrete consolidation and ICFs. The conclusion? Low slump walls had poor consolidation, regardless of the technique used.
On the medium slump panels, external vibration was marginally adequate; internal vibration was best. “Internal vibration was found to provide adequate consolidation for concrete with a slump of 6 inches or greater…As an alternative to internal vibration, adequate consolidation also was achieved through the use of a flowable, high-slump concrete,” states the report.
For the complete report, titled Concrete Consolidation and the Potential for Voids in ICF Walls, click here.
The vibrator should be inserted vertically into the mix, then slowly withdrawn. If the wall is poured in multiple lifts, the vibrator tip should go deep enough to penetrate 3 to 6 in. into the previous layer. The tip should not be withdrawn faster than the air can move upward, about 3 inches per second.
Good concrete consolidation is not complicated. Exact specifications will vary from job to job, but by observing a few general rules, you’ll be able to achieve a strong, well-consolidated wall every time. First, use a concrete mix with a slump of at least 6 inches. Second, brace corners and lintels well and vibrate them thoroughly. Lastly, A trained operator should use a vibrator to consolidate the mix as recommended by your form manufacturer. » Read the Complete Story Here
Taking ICFs to the Max
From rooftops to walk-out basements, Insulating Concrete Forms are being used in uncommon residential applications.
In North Texas, two separate homeowner-builders are demonstrating the versatility of ICFs, using them to construct features that are usually built with other materials. These homebuilders represent a growing number of residential construction experts who are blazing trails with unusual ICF treatments.
Larry Smith’s new, single-story house features 3,000-square feet of living space and an attached 1,000 sq. ft. garage. The Smiths enjoy the outdoors, so the home has three attached porches and a 4,000 sq.ft. deck on top of the house.
The ICF walls extend two feet above the roof to create parapet walls. Foam decking was also used to support the concrete deck surface. Because the exterior of the home has 22 corners, this large rooftop space has an interesting shape. Smith used ICFs on a long interior wall to help support the roof, but its mass will also help regulate interior temperatures. Smith chuckles that this ICF wall is conveniently situated between the master bedroom area and the large “grandkids” retreat, an added soundproofing bonus.
The entire pour—walls and roof—was completed in a single day; 17 trucks poured a total of 170 cubic yards.
Just five miles to the west in Fort Worth, Gary Ivy home has a huge, 3,000 sq. ft. walk-out basement. It houses a 15-foot by 35-foot swimming pool, a wet bar, shuffle-board area and pool table. A wine cellar, surrounded by 12-inch ICF walls, will serve as a safe room during tornado warnings.
Ivy, who constructed the ICF walls with three workers, says, “the ICF part of this project was the easiest part.” Just like Smith, Ivy has become something of a spokesperson for ICF construction. “Everyone who drives by wants to come inside,” he says.
By showcasing interesting treatments in their own homes, builders such as Smith and Ivy are living testimonials to the versatility of ICF technology for use in residential construction.
Building exterior walls using Insulating Concrete Forms (ICFs) can save hundreds of dollars annually in heating and cooling expenses. But constructing an energy-efficient thermal envelope doesn’t always guarantee rock-bottom utility costs. To maximize your energy savings, it is important to ensure the HVAC system is “right-sized” for the home.
A properly sized HVAC system will not only heat and cool efficiently, but also maintain comfortable humidity levels in the home and contribute to a healthier living environment.
Because concrete homes are so inherently energy efficient, owners often can get by with smaller-capacity equipment. But many HVAC contractors are unfamiliar with the superior performance of foam homes and end up installing oversized equipment that not only carries a higher price tag, but also costs more to operate. » Subscribe Now For the Full Story!