While mold seems to get the majority of builder attention this time of year, one can never overlook another threat making its seasonal debut; termites. Because the majority of lumber-built homes are exposed to the elements for long periods of time, they can create the perfect conditions for potential termite infestation. Builders that don’t use termite-deterring construction practices or ignore new construction termite treatments are essentially putting a flashing open sign on their site for termites.
Thankfully, there are many new and time-tested methods that you can use to deter termites before and during the construction phase. The pest control experts at the Mississippi State University Extension (MSUE) say the main ways to prevent termite attacks include applying chemical treatments and using termite-deterring building practices and materials.
But one prevention method cannot stand on its own. A proper game plan of materials, vigilance, and maintenance can help avoid costly loss and damage to both builders and homeowners.
Termite-Deterring Construction Practices
There are three major termite-deterring construction practices, according to MSUE, that all home builders should follow:
- Do not leave wood or other cellulose-based debris underneath or near the finished house.
- Avoid direct contact between soil and all types of wood in the finished building.
- During all phases of construction, prevent moisture problems in, around, and under the finished house.
Termites crave food, moisture, and warmth. The specific practices explained below all support the mission to eliminate the source of these three things that termites crave. As a result, buildings will be less susceptible to termite attack.
Pre-Construction and Foundation Preparation
Termites usually invade homes through the foundation, making the following building practices critical.
Site Preparation
Before starting construction, make sure no stumps, logs, or wood debris are left under the building site. When it’s time to pour the foundation, remove any grade or bracing stakes that are made of wood so they’re not cast into the concrete. Leaving them can provide a direct path for termites through the concrete foundation and into the home, which MSUE says is a common cause of infestation. If the stakes need to stay, use metal or plastic ones instead.
Foundation Moisture Control
To help keep moisture from entering the slab or crawl space, backfill with a free draining soil, incorporate a subgrade drainage system, and install proper above-grade water drainage. Installing vapor/moisture barriers is also recommended. If the home has a crawl space, allow at least 24 inches of ground clearance to promote adequate ventilation and provide enough space for future termite inspections and treatments.
Basement Wall Crack Prevention
Homes with below-grade basements require different methods. Due to shifting temperatures throughout the year, concrete masonry foundations can expand and contract. The shrinkage caused by this process can cause cracks large enough for termites to enter. According to the National Concrete Masonry Association, there are multiple ways to minimize crack development in concrete basement walls.
Before construction, cure concrete blocks for a minimum of seven days and apply liberal amounts of topical curing compounds to reduce shrinkage. Keeping the concrete as dry as possible during construction can also help prevent shrinkage cracking. Storing blocks on pallets to keep them dry, laying only dry blocks, and keeping a reinforced weatherproof membrane over uncompleted walls at the end of the workday are all ways you can prevent future cracking. Waterproofing measures, like exterior membranes, also help keep termites out of the foundation.
A reinforced bond beam at or near the top of the wall works well and provides a cap that prevents termites from entering the home through the empty cores of ungrouted blocks. Enforcing the horizontal bed joints provides additional tensile strength that won’t completely prevent cracking. But it will ensure the cracks are too small for termites to get through. Liberal applications of topical curing compounds should decrease cracking.
During Construction
Even if the foundation is protected, termites can still invade from above the soil if you give them the means to do so.
Ground Clearance
While building the home, whether it’s part of your building code or not, make sure that all wood elements are as far from the soil as possible. Nonstructural wood elements need at least six inches of clearance, while structural elements (wood framing, sill plates, and sheathing) need at least eight inches. These minimum distances help prevent external termite entry.
Pre Dry-In Moisture Control Methods
Before a home reaches the dry-in stage, it’s necessary to make sure the house prevents excess moisture buildup near the foundation. Be sure outdoor window ledges, porches, patios, and walkways grade slope away from the building. Install gutters and downspouts to channel water away from the foundation wall. Properly installing the roof flashing — especially around chimneys — is another way to close a common termite entry point.
Post Dry-In Moisture Control
When applying the structural finishing touches, remember these tips. Prevent plumbing leaks or other water in the crawl space by draining condensation from air conditioners and other appliances outside of the house, not under the crawl space. Install vent access for clothes dryer exhaust so it goes outside and not under the crawl space.
Avoid landscaping too close to the foundation because too much digging can disturb the treated soil barrier (more on that later). Mulch is popular, but if you’re building the home in a termite-prevalent area, mulch’s moisture retention properties can act as a loud dinner bell for termites. They won’t be interested in the mulch itself, but it attracts them to the home. If the mulch touches any wood siding, doors, or window frames, you’ve given them a point of entry. Crushed stone or pea gravel is a comparable and safer alternative.
Termite-Resistant Building Materials
Using termite-deterring building practices is just one part of a comprehensive deterrent plan. Usually, additional resources like specific building materials are also helpful.
Here are some common building materials recommended by termite experts. But remember to always consult your local building code to confirm which of the listed materials are permitted for use.
Lumber
Using wood that is pressure-treated with chemicals is a common way to help mitigate termite spread. Many state building codes require that any wood that contacts soil must be pressure-treated. More expensive, resinous woods like cedar are also a good choice because of their natural insect-deterring properties. Termite-resistant lumber is helpful, but it is not a substitute for comprehensive prevention methods or routine maintenance.
Non-Wood Materials
Whenever possible, use termite-resistant framing materials like steel, brick, concrete, and stone. For termite-resistant sheathing and siding, consider aluminum, steel, rigid plastics, gypsum, wood-plastic composites, and fiber cement.
Foundation Barriers
Because termites usually enter a home through the foundation, there are many materials available to help seal and protect it.
Metal Shields and Mesh
Install metal termite shields between the top of the foundation wall and the sill plate, between support piers and beams, and in similar places. Before pouring the foundation’s concrete slab, install termite-proof collars on pipes, conduits, and other utilities that will penetrate the finished slab.
For homes with larger foundations, a metal mesh barrier can help. Mesh made from grade 304 or 316 wire with a minimum diameter of 0.01 inches (0.18 mm) and a maximum aperture size of 0.02 inches x 0.01 inches (0.66 mm x 0.45 mm) can be used as a perimeter barrier for masonry exterior walls. It can also serve as a continuous barrier under concrete slabs or as a barrier under joints and for utility penetrations.
Sand/Crushed Basalt Barriers
A newer foundation barrier solution involves sand or crushed basalt. Pouring a barrier of the material under or around the foundation can stop termites from accessing the foundation. When graded and shaped a certain way, according to ongoing research, the sand or basalt becomes too big for termites to move and creates spaces that are too small for them to burrow through. While sand/basalt is a chemical-free solution, it’s still not very common in the U.S. and not recommended for all regions.
Pest Control Pretreatment Methods
Even if your team applies all the appropriate construction practices and uses termite-deterring building materials, it’s often not enough to prevent future termite infestation. Nationally, the U.S. Department of Housing and Urban Development requires termite pretreatment for 34 states, and local requirements exist in most others.
The three most common types of termite treatments across the U.S. are soil treatment, wood treatment, and bait stations. Because insecticides can be dangerous if not handled or applied properly, these pretreatment methods often require professional pesticide applicators. Here’s a basic overview of the three treatment types to help you determine which one will work best for your project.
Soil Treatment
Soil treatment is when a professional pest control company applies insecticides directly to the soil underneath and next to the home’s foundation. This creates a horizontal barrier that stops subterranean termites from entering the foundation. From a contractor’s standpoint, this method requires the most amount of coordination and prep. The treatment is applied in multiple stages, including before the foundation is finished and again around the perimeter after construction, final grading, and landscaping is complete.
Wood Treatment
Borate-based wood treatment — commonly called Bora-Care — is a newer solution that is becoming more popular with contractors because it is simpler (and often cheaper) than soil treatment. Borate is a salt-like natural pest control material made from a chemical compound of oxygen and boron. It’s virtually harmless to humans but deadly if ingested by termites.
It’s possible to buy lumber that is pressure-treated with borate or apply it later as a liquid preservative. When applied as a preservative, a professional applicator will spray vulnerable areas like floor joists, studs, sill plates, and floor beams. If considering this option, check your state’s building codes. Some states, like Mississippi, still require a post-construction perimeter insecticide treatment along with borate-treated wood.
Bait Stations
Termite bait stations are a more recent innovation and have many advantages. They use a limited amount of insecticide in targeted locations, which makes them relatively eco-friendly. They can also be used in situations where liquid termiticides are prohibited, such as near water sources.
Bait stations are installed after the final grade and landscaping is completed, meaning there’s a lot less coordination during construction compared to the other two methods. But they can be expensive and require annual inspections and maintenance, so that’s worth considering when creating a proposal.
In most states, home builders are responsible for preventing termite infestations. There are effective steps you can take, like using specific construction methods or termite-deterring building materials. But some pretreatment methods are best left to the pest control professionals and require additional planning. TechWood innovative lumber treatments are all fully-warrantied against termites and wood-boring insects, providing both jobsite and post-construction protection for your materials.
