Can Termites Eat Redwood? | The Uncomfortable Truth

If you built a redwood deck or fence specifically because someone told you termites “won’t touch the stuff,” you are not alone. Redwood has a well-earned reputation for natural beauty and durability. The catch is that “resistant” is not the same as “immune”—a distinction that can save you thousands of dollars in repairs.

This article separates the marketing from the biology. Redwood’s tannins and tight grain do make it a less preferred menu item for termites. But under the right—or rather, wrong—conditions, termites will absolutely eat it. Here is when that happens and what you can do about it.

Why Redwood Is Naturally Unappealing to Termites

Redwood’s defense comes down to two main factors: chemical weapons and structural density. The heartwood contains natural compounds called tannins that create a bitter taste and are slightly toxic to termites and decay fungi.

Redwood is also physically denser than softwoods like pine. This makes it harder for termites to tunnel through and build their colonies. It requires more energy to chew, which is why they prefer softer, more nutritious options.

This is why redwood and cedar are go-to choices for outdoor projects. They resist rot and insects better than most untreated lumber, providing a natural barrier that synthetic treatments try to mimic.

Why The “Resistant” Label Can Fool Homeowners

The word “resistant” is doing a lot of heavy lifting. Homeowners often hear it and think “termite-proof,” which stops them from thinking about prevention entirely. That assumption can be a costly mistake.

• Moisture Overrides Everything: Termites need moisture to survive. If redwood is constantly wet from sprinklers, ground contact, or rain, it becomes vulnerable. Rot softens the wood and lowers the tannin barrier.
• Weathering Removes Natural Defenses: Sun and rain break down redwood’s surface tannins over time. Weathered, gray redwood has significantly less natural protection than freshly milled heartwood.
• Species-Specific Tastes: Subterranean termites, the most common and destructive type in the US, are aggressive. Drywood termites are less picky. A hungry colony will test wood they normally avoid.
• No-Choice Scenarios Matter: The famous USDA study on termite feeding only proves redwood is less preferred. When termites have a choice, they avoid it. When their only food source is a redwood porch, they eat it.
• Existing Damage Attracts More Pests: Once termites breach the surface, they open the door for fungi and other insects, accelerating decay and making the wood even more edible.

Think of redwood’s resistance as a strong deterrent rather than a lethal poison. It makes redwood a bad first choice for termites, but a desperate or well-established colony will not starve waiting for something tastier.

What The USDA Study Actually Found

A USDA termite feeding study placed termites in a no-choice chamber with single wood varieties for six weeks. Redwood was one of six species that termites consumed less of, alongside Brazilian jatoba and Peruvian walnut.

This is the strongest evidence we have on the topic. It confirms redwood is a low-preference food, but it explicitly shows termites will still gnaw on it. The study design is critical: given no alternative, termites make do.

The table shows that while redwood is not immune, it performs significantly better than the softwoods typically used for framing. This makes it an excellent choice for decks, siding, and outdoor furniture—as long as the limitations are respected.

How to Protect Your Redwood Investment

Protecting redwood is mostly about smart installation and regular maintenance. While the wood offers a strong head start, it is not a set-it-and-forget-it solution. A few simple habits can dramatically extend its lifespan and keep termites from testing its limits.

1. Keep It Off the Ground: Use concrete piers or metal stands for redwood posts. Direct soil contact is the fastest way to invite termites, regardless of the wood species.
2. Divert Water Away: Ensure sprinklers do not constantly soak your redwood siding or deck. Redirect downspouts. Redwood stays resilient only when it stays dry.
3. Apply a Sealant or Stain: A high-quality penetrating oil or stain locks out moisture and UV rays. This preserves the tannins and keeps the wood hard.
4. Inspect Annually: Look for mud tubes climbing foundation walls or the underside of deck boards. Tap the redwood with a screwdriver. If it sounds hollow or sinks in, you have a problem.
5. Use a Termite Barrier: Liquid termiticides applied to the soil around your foundation create a chemical boundary. This protects your home’s structure regardless of the framing wood.

These steps are not complicated, but they require consistency. A weekend of inspection and a can of sealant every few years is a small price to avoid a costly infestation down the road.

Redwood vs. Other “Resistant” Woods

Redwood is often compared to cedar and pressure-treated pine when choosing outdoor lumber. Each material has trade-offs regarding cost, durability, and termite resistance that are worth understanding before you build.

Redwood’s natural resistance is largely due to its high concentration of tannins, which pest control experts say can make it less palatable — Rogall’s guide on redwood tannins and termite resistance explains the conditions under which this defense can break down over time.

Each wood has its place depending on your budget and local climate. Redwood offers the best balance of natural beauty and pest resistance, but it commands a premium price that may not be necessary if you are willing to maintain pressure-treated wood properly.

The Bottom Line

Can termites eat redwood? Yes. The word “resistant” means they will actively choose a different path if one is available. But if your home is in a high termite zone and your redwood is damp, weathered, or touching the ground, you cannot rely solely on the wood’s natural chemistry to protect your investment.

A licensed structural pest inspector or a local pest control professional can evaluate your specific property’s termite risk and recommend the right combination of wood choice, drainage improvements, and chemical barriers for your situation.