How to Prevent Termites in New Construction Projects

Published on October 3, 2023 by Nate Bortz

Because stick-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. Using these construction practices will ensure the insecticide treatments work as intended. 

This article focuses on building practices and materials that contractors can use to help prevent termites before and during construction. But we’ll also briefly discuss the traditional and newer pesticide pre-treatment options to help you set your budget and plan your bid.

Use this outline to quickly jump to any topic:

• Termite-Deterring Construction Practices
  
  
• Termite-Resistant Building Materials
  
  
• Pest Control Pretreatment Methods
  

Termite-Deterring Construction Practices

There are three major termite-deterring construction practices, according to MSUE, that all home builders should follow:

1. Do not leave wood or other cellulose-based debris underneath or near the finished house.
   
   
2. Avoid direct contact between soil and all types of wood in the finished building.
   
   
3. 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.

Summary

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.  

Taking the time to understand and consider the termite prevention methods available to you will make sure you choose the best one for your team and will give your clients confidence in your work.

Sources

Lawrence, R. (2019, July 16). How Home Builders Can Protect Their Properties from Termites. Retrieved from https://www.builderonline.com/building/structure-durability/how-home-builders-can-protect-their-properties-from-termites_o 

Layton, B. (2021, March). What Homebuilders Need to Know About Termites. Retrieved from http://extension.msstate.edu/publications/what-homebuilders-need-know-about-termites 

Livingston, M. (2021, March 01). What Options Do I Have for Pre-Construction Termite Treatment? Retrieved from https://remedypest.com/what-options-do-i-have-for-pre-construction-termite-treatment/ 

National Concrete Masonry Association. (n.d.). TEK 03-09A: Strategies for Termite Resistance. Retrieved from https://ncma.org/resource/strategies-for-termite-resistance/ 

NC State Extension. (2023, February 24). Termite Prevention – Approaches for New Construction. Retrieved from https://content.ces.ncsu.edu/termite-prevention-approaches-for-new-construction 

North Carolina Department of Agricultural & Consumer Services. (n.d.) Pre-Construction Subterranean Termite Control. Retrieved from https://www.ncagr.gov/SPCAP/structural/pubs/preconstruction.htm 

Office of Energy Efficiency and Renewable Energy. (2022, December 04). Termite-Resistant Foundations and Walls. Retrieved from https://basc.pnnl.gov/resource-guides/termite-resistant-foundations-and-walls 

Orkin. (n.d.). Preconstruction Termite Control. Retrieved from https://www.orkin.com/pests/termites/real-estate/preconstruction-termite-control 

Orkin. (n.d.). Termite Baits. Retrieved from https://www.orkin.com/pests/termites/termite-baits 

Perma-Chink Systems, Inc. (2023, May 11). How Borates Protect Wood. Retrieved from https://www.permachink.com/resources/how-borates-protect-wood 

U.S. Census Bureau. (2023, September 19). Monthly New Residential Construction, August 2023. Retrieved From https://www.census.gov/construction/nrc/pdf/newresconst.pdf 

U.S. Department of Housing and Urban Development. (2021, November 03). Termite Treatment Exception Areas. Retrieved from https://www.hud.gov/sites/dfiles/SFH/documents/SFH_POLI_TERMITE.pdf 

Webb, D. (2023, January 17). How to Help Prevent Termites when Building a House. Retrieved from https://www.terminix.com/termites/termite-new-construction/