FOCUS ON CONSTRUCTION: Construction Basics: Codes and Foundation Types

In the world of pest management, we must deal daily with varied construction techniques and quality. Unfortunately, whether we are performing termite or pest control work, we frequently cannot see important building components. These components might be hidden behind walls, below the floor or buried in the ground. This challenge forces pest control operators to “visualize” the hidden areas in order to solve pest challenges.

Anyone who works in the field must know various construction characteristics. Construction education is an ongoing process that cannot be ignored. Most pests require food, water and harborage. As an industry, we have placed great emphasis on the food and water controls but have largely ignored harborage, perhaps believing that this part of the triad is too complicated or that styles vary too greatly. Here’s a look at construction that will help pest management professionals understand how it affects harborage.

TRANSLATING BUILDING CODES. Building codes are the specialists’ specialty. Nothing in the realm of pest management is more complicated and confusing. One building code expert who now works for a building materials association recently noted, “Dealing with building code development is the most complex task that we face as engineers. It takes a special skill to follow the codes.” A little background information is helpful in understanding these building codes.

Building codes are undergoing a major transition (see related story below). Code bodies develop model codes and test products for acceptability in construction. Previously, there were four code bodies: the Southern Building Code Congress International (SBCCI) in the South; Building Officials and Code Administrators (BOCA) in the Midwest; the International Conference of Building Officials (ICBO) in the West; and the Council of American Building Officials (CABO) in the North. Each group historically had developed model codes in their regions. Local governments would use the model code to develop local building codes.

While some autonomy remains, the four major model code bodies are in the process of merging into the International Code Council (ICC). The ICC will administer the International Building Code and the International Residential Code. Codes can be confusing and are easily misinterpreted. Codes also call for clearance between exposed soil and the building, both outside and inside crawls and basements. Any WDI inspector will tell you that what is in the code and what is actually on the structure can be dramatically different. The main objective of building codes with respect to sections that affect the pest management industry is life safety.

The pest management industry historically has not had much to do with codes. Recent events, however, forced the industry to work with codes to obtain severe restrictions on foamboard below grade in areas of heavy termite infestations. Participating on this massive effort, which ultimately led to success, was the Association of Pest Control Regulatory Officials (ASPCRO); the National Pest Management Association (NPMA); researchers and manufacturers of building materials and other interested parties.

Francis Bacon (1561-1626) said, “Houses are built to live in and not to look on: therefore let use be preferred before uniformity.” Bacon never lived among building code inspectors.

BASICS OF CONSTRUCTION. Engineers describe three types of foundation construction design covering most single-family housing and even commercial buildings nationwide. These types can be classified as concrete slab, T-foundation and pier. Slabs can be above grade, on grade and below grade. The pest control industry frequently defines building types as slab, crawl or basement, but those terms define access relative to the surrounding grade rather than foundations. Note that construction terms and design vary throughout the country and local building practices must be considered by the PCO.

Concrete Slabs. There are generally three types of concrete slabs: monolithic, floating and supported. Understanding the different types is required in order to perform proper inspections and control work, regardless of pest. Slabs are suited for level grade building lots and are the least expensive type of foundation. At any pest control meeting, we hear of discussions about slabs and it seems that understanding slabs should be considered basic. Slab types and design, however, are often misjudged by the PCO, leading to inadequate pest management attempts.

Monolithic. Monolithic slabs are poured concrete slabs with attached footers (see diagram on page 94). The advantage of a monolithic slab is that it is poured in one step and is designed so that the load-bearing portions are strategically placed on the perimeter. Monolithic slabs are suited for soils that are expansive, in that there is the attached footer for stability.

Supported. Supported slabs are poured slabs that rest on other building components built or poured independently of the slab (see diagram on page 94). Commonly supported slabs are basement floor slabs that rest on the poured footer (T-foundation). Supported slabs are separated from other components of the foundation by expansion joints.

Floating. Floating slabs are poured slabs that are supported by fill or soil and not by other foundation components (see diagram on page 94). Floating slabs are commonly found between T-foundation walls resting on filled soil. The term “floating” is derived from the fact that the slab is confined by foundation walls but is not supported by the walls. While the term “floating” might give the impression that there is significant movement of the unanchored slab, little movement occurs. Floating slabs are frequently used with T-foundations.

Determining Different Slab Types. Determining whether a slab is a monolithic slab can be successfully done by probing soil and looking for the absence of expansion joints inside. Also, with a monolithic slab, slab thickness will vary with a characteristic monolithic slab having “poured in” footers. Determining whether a slab is floating or supported can be difficult. If there is no way to tell the depth of the stem wall or T-wall foundation, it is impossible to tell whether the slab rests on the footer or on soil.

T-Wall Foundations and Piers. Terminology varies throughout the country, but the basic T-wall foundation is found in most regions. In a T-wall foundation, a footer is poured anywhere from just below grade to below basement floor level, depending on whether the final construction will be slab, crawl or basement. In all cases, the footer will be below the lowest level of the living space. After the footer is poured, concrete can be formed to pour the foundation or block, brick or hollow tile can be used for the foundation wall. Even insulating concrete forms (see below) can be used as foundation on top of the footer to form. Frequently, after a T-wall is built, a slab or pier type of foundation is added between the walls. If it is a pier foundation, a crawlspace or basement type of finished space can be expected (see diagram below).

Pest Management Hazards of Concrete and Masonry Foundations. Regardless of the type of concrete or masonry foundation, there are inherent cracks that may occur in mortar, joints or in slabs. PCOs in the termite business can relay countless stories about subterranean termite infiltration through pinhole failures in even mortar, where it appears that the termites just appear midway in a block wall. Building codes make a half-hearted attempt to reduce termite infiltration by requiring a physical barrier such as a termite shield, which was never supposed to keep termites away, just force their activity into the open for observation and control. Solid block or mortar filled block is sometimes required between the foundation and the sill, but over a period of years, the mortar breaks and it is common to have gaps from on top of the sill to the footer. Termites have a knack for finding these gaps.

NEW TECHNOLOGIES. There are several new technologies in building foundations that are important to note.
1. Foam blocks (also called insulated concrete forms) are blocks or walls of foam that rest on the foundation. Concrete is poured into the foam, which acts as a form board. The pest control industry has a history of opposing such construction in areas of heavy infestation and while the ICC does not permit the forms in those areas, local code officials sometimes preempt the ICC code and permit construction due to the energy savings.
2. Wood foundations/pressure treated wood foundations are considered a new technology. The wood is placed on the soil or on the footer and is considered termite and decay proof. Recently EPA announced an agreement with the manufacturers of pressure-treated lumber (with chromated copper arsenate) to phase out most uses of that product in 2003 (see related story at www.pctonline.com/lumber). There will be substitute lumber products, so we can expect to see wood foundations.
3. Straw bale houses are gaining popularity as a “green” construction method. Straw bale is similar to “sod” houses on the prairies. Straw bale houses have finished interior and exterior so that it might not be apparent that the house is made of straw bales. According to proponents, cities such as Austin, Texas, permit the use of straw bale houses under their modified code. Other areas in the Southwest are experimenting with straw bale houses.

FOUNDATIONS UNLIMITED. Foundation technology will continue to change and improve. For the foreseeable future, traditional foundations will continue to be the foundation of choice, but we can expect to see new technologies develop in the interest of energy efficiency and cost reduction. PCOs must be prepared to:
1. Include construction basics in technician training programs.
2. Keep informed as to building codes in their jurisdiction.
3. Get involved in shaping building codes.
4. Teach technicians to “visualize” construction when they cannot see what is actually below grade. This will help in solving pest problems and also will help with more effective termite control.
5. Keep informed on these issues. Understanding pest management by understanding the components of the structure means more effective pest management. More effective pest management means it will be IPM friendly.

The author is president of Pro-Tech Pest Management, Raleigh, N.C. He can be reached at gbaumann@pctonline.com.