Precast concrete walls save time and money and result in dry basements that meet the government’s IRC building codes.
By Bridget McCrea
When looking for a new home, nearly everyone’s first concern is how much square footage they can get for their buck. One good way to make the space stretch with little additional cost is with a finished basement. The problem is that, among home buyers, the word “basement” usually conjures up images of damp, dark spaces that hardly rank as good living and playing spaces.
But the good news is that precast concrete foundation systems, designed for use in residential and commercial construction, can eliminate those concerns. For the architects, engineers and contractors at Savannah Green, a large residential development in Normal, Ill., precast concrete basement walls were a natural choice.
The neighborhood combines affordability with high quality and comprises 369 single- and multi-family homes on a 76-acre infill site. “We know the first thing people will ask is how much home they’re getting, and how much more they can get by finishing the basement,” says Rick Allender, vice president at CDG-Architects, Engineers and Planners in Springfield, Ill.
Allender points to the precast basement walls – which don’t crack or leak like some of their cast-in-place counterparts – as an easy solution. “Homeowners can turn a 1,200-square foot starter home into 2,400 square feet of living space without having to worry about basement cracks or leakage,” says Allender.
The project’s builders also benefit because the basement walls meet the new International Residential Codes (IRC) for energy efficiency and include a 15-year warranty against manufacturing defects and sidewall water penetration. CDG, which handles individual site plans and engineering for about 500 homes a year, specifies precast concrete systems on every home it designs, according to Allender.
“We’ve even incorporated them into commercial projects and custom homes,” he says, adding that the biggest advantage over a poured foundation is that precast walls don’t shrink after being installed in the ground. “If you were to pour a continuous foundation, you’d end up with shrinkage cracks – and that means leaks,” says Allender. “The precast walls are provided in custom panel sizes up to 16 feet long. The panels shrink while they’re in their forms at the plant, in a controlled environment. That means no cracks and no leaks.”
Precast concrete basement walls can be insulated and pre-studded for easy finishing, which is yet another benefit. The joints are also sealed with specialized concrete sealer, says Allender, and require just one day or less to install, compared to the several days or weeks that a cast-in-place basement requires. Combined, those advantages result in significant cost savings on each house built. “When you factor everything in – and take into consideration the cost of waterproofing the outside of a traditional foundation, which is unnecessary with most precast products – the savings really add up,” says Allender. “I’d say we come out a couple of thousand dollars ahead on each home.”
Five years ago, Nick Capranica, president and COO of Construx of Illinois Inc. in Springfield, Ill., was staring at a stack of contracts for 50 new homes that his company couldn’t deliver fast enough, thanks to inclement weather.
“It was cold and raining, so we couldn’t get the foundations poured,” recalls Capranica, who is both the builder and developer on the Savannah Green project. Capranica solved the problem by switching from cast-in-place basements to precast concrete basements – a move that he calls “one of the best things to ever happen” to his company.
“We went from building 50 homes a year to building more than 400 last year,” Capranica explains. “We use them on our apartments, all of our multi-family units, single-family homes and light commercial projects.” When it came time to develop the Savannah Green community, Capranica says there was little doubt in his mind that precast basement walls would be his substrate of choice for the homes.
Within the development, lots range from 40 to 50 feet wide, which puts the homes in close proximity to one another and makes pouring in place a real chore. “It’s congested in there with a home every 50 feet on center,” he explains. “Because we’re using precast walls, we can just dig one after another and set two houses per day with no problem at all.” Capranica, who has been using wall systems manufactured by Superior Walls of Central Illinois for the last five years, says the raw costs are comparative to cast-in-place foundations, with one major exception: Factor in soft costs like time spent on the project, the customer service callbacks that come when the basements leak, and the ease of being able to add an egress window or walk-out basement, and there is no comparison. “Our callbacks have been cut by 90 percent because of our switch,” says Capranica. “Plus, we have the added flexibility of being able to make a change when we pre-sell a home before the walls are fabricated. They’re very versatile and have performed very well for us.”
Allender calls that flexibility and versatility the most significant advantage of using precast concrete walls on a project like Savannah Green. The walls prove especially useful in areas where the soil is bad and in need of digging and replacement. They also came in handy recently when a slight elevation error was made on the project.
“One foundation was put in at an elevation that just wouldn’t work with the grades around it,” Allender explains. “We were able to pull the walls out, set them off to the side, (dig some more) and set those walls back in place. With a cast-in-place system, that would have been impossible.”
From the builder’s standpoint, another great advantage of a precast concrete foundation is that carpenter crews can immediately start framing once the foundation walls are set – no curing time for the concrete is needed. An essential note Capranica emphasizes is that the basement floor must be poured – and the first floor deck must be installed or the precast walls be braced – prior to backfilling the foundation. As long as this is planned for, it does not affect the schedule.
Concrete basement walls go beyond staying dry and creating more space for homeowners. The walls also meet stringent new building codes set forth by the government. During the October 2002 Code Conference in Fort Worth, Texas, for example, a joint resolution was reached to consolidate the three model building codes (BOCA, SBCCI and ICBO) under the International Code Council.
According to Aaron Schoeneberger, marketing director for Superior Walls in New Holland, Pa., the emphasis in the recently published IRC is energy efficiency. So far, 43 states have adopted all or a portion of the 2003 code, which requires that basements be insulated during the construction of the home. The “R-value” required for each home is calculated based on the EPA’s climatic zones.
“Our walls are provided with R-5 insulation and equipped with built-in stud cavities and furring strips for adding more insulation,” says Schoeneberger. “This means that a Superior Walls basement may easily be finished up to R-24 with no additional framing.”
This year, Superior Walls introduced a new wall system, Superior Walls Xi, which meets the Energy Conservation Code requirements (IECC, IRC Chapter 11), with no additional insulation. Schoeneberger says the cornerstone of Superior Walls’ products is not simply the precast concrete, but the manufacturing process that the company uses regarding insulation.
“Our products come pre-insulated, and that insulation is bonded to the concrete,” says Schoeneberger. “It’s also the speed with which our walls are manufactured in a factory-controlled environment, thus ensuring there are no cracks before they’re panelized and bolted together. The panel joints are sealed with a specialized sealer and ready to be installed in a much shorter time period than a cast-in-place basement.”
The walls are also environmentally friendly, or “green,” says Kale Walker, president of Superior Walls of Central Illinois. While the typical poured foundation requires about 60 yards of concrete, a precast basement uses only about 18 yards, thus conserving materials and reducing the mess and waste on the job site. Spillage can be kept to a minimum because the walls arrive preassembled and ready for installation, he adds.
Because it’s insulated, the wall system itself is also energy efficient, unlike a typical concrete foundation, which “has no insulation in it and no insulating value,” says Walker, adding that Superior Walls’ products include 1 inch of built-in Styrofoam, which gives them an R-5 energy value and also acts as a thermal break. “Where normally in a basement you might get a lot of dampness and moisture because of condensation, with the built-in insulation in the wall you don’t have condensation problems, thanks to the thermal break.”
When Rich and Bert Hurst sat down three years ago to build a new home for their family that would one day be converted into a bed and breakfast establishment, one of the first choices they made was precast concrete for their basement structure.
Well-versed in the home building process, the Hursts co-own Hurst Brothers Development Co. in Ephrata, Pa., and say the precast walls were a shoo-in for their new abode.
“We’ve always found that the precast walls produce the driest basement you can find,” says Bert Hurst. “Choosing them for our new home was an easy choice.” Weaver Precast of Ephrata, Pa., manufactured, delivered and installed the walls.
Rick Miller, vice president of sales and marketing for the precaster, says the size of the home presented a few design challenges, mainly because it required a cutup, detailed foundation that encompassed 229 lineal feet of 10-foot-high walls. “They wanted additional space in the basement, so they went with the higher wall height,” says Miller.
The home’s basement included 20 corners and 27 panels that took the precaster one day plus two hours the following day to complete. A cast-in-place basement would have taken at least five days to finish, says Miller. Along with the time savings, the Hursts’ choice of precast walls also puts their new home in compliance with the new IRC codes – a factor that Weaver says has increased customers’ interest in precast concrete foundation systems.
“Demand for the walls is increasing every year,” says Miller, who estimates that sales of the walls have grown 15 percent to 20 percent over the last five years. He adds that a lot of code changes are eing implemented that make precast concrete a much more favorable choice over cast-in-place.
The Hursts, who have lived in their home for about three years now, say they’re just pleased that the basement has remained dry and that the installation met their expectations. “The basement is just immaculate,” says Hurst. “It worked out very well, and we’re pleased with our choice.”
Kenneth Bond says
We are looking at the use of insulated precast basement construction for a small residential unit that will use the space under a domestic driveway? The finished space will need to be highly insulated, as close to passive his standard as we can. We are looking for examples/ details we can use?
Mason Nichols says
Thank you for the message! Your best bet for this project would be to contact a local precaster to assist you. You can use our website’s Find feature to locate a precast manufacturer in your area. Simply click the link, then select “Precaster.” You can then search by state or mile radius for the specific product(s) you are interested in.
Arthur Morrison says
I had never really thought about precast concrete walls as an option for basement foundation, but you’re making some pretty good points in the article. It is especially interesting to learn that they don’t crack or leak like walls that we cast-in-place. I assume that that has something to do with the fact that they were made in a factory and then shipped to the site before being placed in the ground.
Helen Martin says
Thank you so much, NPCA. An inspector from Prompt Building Inspections has suggested me to search related information on foundation choices for a better understanding. I am very happy to know about the basement foundation system.