Wood decay, insect damage, and the structural problems that follow are common concerns for homeowners in Spokane and the surrounding area. The semi-arid climate here, with hot dry summers, cold snowy winters, and real freeze-thaw cycles, creates conditions that invite moisture into wood framing, siding, and decks, even though we do not experience the constant rain of coastal regions. This guide explains what rot and insect damage actually are, how to recognize them before they advance, what they do to a home's structure, and how to decide between repair and replacement. It is written for homeowners who want to understand the problem clearly and make informed decisions with their carpenter.
The pages that follow cover the difference between dry rot and wet rot, how insect damage differs from fungal decay, the signs to watch for, what happens to a floor or deck as wood loses strength, and the honest criteria for deciding whether a member can be repaired or must be replaced. We have also outlined the separate roles of the pest control operator, the carpenter, the structural engineer, and the building department, because knowing who does what is your best protection against incomplete or unnecessary work.
Dry Rot and Wet Rot: Not the Same Problem
Dry rot and wet rot are both fungal decay, but they behave differently and require different moisture conditions. Dry rot is caused by a fungus that needs sustained moisture in the wood, not standing water, but persistent dampness from capillary rise, condensation, or slow seepage. Once established, dry rot can spread through sound wood and even travel across masonry to reach new timber. Wet rot, by contrast, needs a direct and ongoing water source and remains localized to that source. In Spokane's climate, where freeze-thaw cycles crack paint and caulk, and where roof and gutter failures allow water to reach framing, dry rot is the more common problem in older homes. It appears as cubical cracking in the wood grain, with a dry, crumbly texture and a color that ranges from light tan to dark brown. The wood becomes lighter and loses its density as the fungus consumes the cellulose.
Wet rot produces a different appearance: the wood darkens, becomes spongy or soft to the touch, and may feel almost rubbery when fresh. The distinction matters because the repair strategy differs. Both conditions are hidden by paint and caulk, which can look perfectly sound even when the wood beneath has lost significant section. A paint film that blisters, holds water, or peels repeatedly often signals moisture movement in the wood below, even if the surface appears intact. This is why visual inspection alone is not enough to measure the extent of decay. A screwdriver or awl, carefully applied, will penetrate sound wood only with real pressure, but will sink easily into decayed wood. Probing is how a carpenter determines what is there and what must come out.
Termite and Beetle Damage, and How It Differs from Rot
Termites and wood-boring beetles cause damage that looks and behaves differently from fungal rot. Termites hollow a wood member from the inside, typically along the grain, often leaving a thin shell of sound wood on the surface that can look deceptively intact. They may also leave mud tubes on masonry as they travel. Wood-boring beetles create exit holes (often round and clean-edged) and leave behind a fine powder called frass. Because termites are rare in the Spokane area, the wood-damaging insect most commonly encountered in the Inland Northwest is the carpenter ant, which tunnels through moisture-softened wood, particularly near rooflines, in deck ledgers, and around foundation sills. Carpenter ants do not eat the wood as termites do; they hollow it out to create galleries for nesting. The damage resembles wet rot in appearance, the wood becomes soft and loses integrity, but the tunneling pattern and the presence of sawdust or frass, along with live ants, distinguish it from fungal decay.
Insect damage and fungal decay frequently occur together because the same moisture that invites rot also attracts insects. A member that has been wet long enough to support fungal growth has often become soft enough to attract carpenter ants or beetles. Identifying and treating insect infestations is the work of a licensed or registered pest control operator in your state, not a carpenter. Once you have a pest inspection report that documents the damage, a carpenter can remove the affected wood and rebuild the member or replace it entirely. The carpenter's role is to repair the structure from that report. We do not treat insects, apply pesticides, or claim that an infestation has been eliminated. That is the pest operator's responsibility, and it is a separate trade with its own licensing and regulations.
Reading the Signs Before You Open Anything Up
A homeowner does not need specialized tools to spot potential decay and insect damage. Begin with a visual walk-around, both inside and out. Look for paint that blisters, peels, or holds moisture at window sills, door thresholds, and the base of exterior trim. Check trim boards and fascia by pressing them firmly with your thumb; sound wood resists, while decayed wood gives way. A screwdriver pressed sideways into fascia or a sill should require real force; if it sinks in easily, moisture and decay are likely present. Inside, watch for doors and windows that no longer close smoothly, or that have shifted in their frames, because this often signals movement in the framing or sill beneath. A soft or springy patch of floor, particularly in bathrooms, kitchens, or near exterior walls, deserves attention. Deck boards that flex more than they should, or a ledger board that moves when you push on it, are warning signs. A musty or moldy smell in a basement, crawlspace, or enclosed porch points to moisture that may be supporting decay.
None of these signs is an emergency, but all of them are worth investigating promptly. The important thing to understand is that surface appearance almost always understates the extent of decay. Paint can hide rot, and a wood member can lose significant internal section while its surface still looks sound. This is why probing with a screwdriver or awl is the standard first step. A carpenter will use these simple tools to determine how deep the decay goes, how much sound section remains, and whether the damage is localized or widespread. Probing takes time and care, but it is the only way to move from guessing to knowing. If you have noticed any of these signs, a free estimate begins with this kind of careful inspection.
What Decay Does to a Floor, a Deck and a Wall
To understand what decay does to a structure, it helps to think about how loads move through a home. A floor begins with the subfloor (the layer of boards or plywood nailed to the joists), which distributes the weight of furniture and people across the floor joists beneath. Those joists rest on the rim joist (the board around the perimeter of the floor frame) and on the sill plate (the board bolted to the top of the foundation wall). Outside the house, a deck ledger board connects the deck frame to the rim joist or band board of the house. Each of these members carries a specific load. When wood decays and loses section, it loses the ability to carry that load. The progression is gradual and measurable. The first thing a homeowner notices is usually a loss of stiffness: the floor feels bouncy or springy underfoot, or a deck board flexes more than it should. This happens because the member has lost enough section that it bends more easily under load. This is not a structural failure yet, but it is a clear signal that the wood is compromised and that the problem will advance if the moisture source is not closed.
As decay continues, the loss of section becomes more severe. A joist that has lost half its depth may still carry its design load, but it has much less margin for error and much less ability to handle impacts or concentrated loads. The ledger connection where a deck meets the house is particularly important to monitor, because if the ledger pulls away from the rim joist due to decay, the entire deck can separate from the house. A soft or rotted sill plate allows the rim joist and floor frame to settle unevenly, which is why doors and windows begin to bind. The key point is that decay is a progressive loss of strength and stiffness, not a sudden failure. A floor that feels soft today will not collapse tomorrow, but if the water source is not addressed, the decay will continue, and the cost to repair will rise. This is why prompt inspection and closure of the water path, whether that means fixing a roof leak, improving drainage, or repairing flashing, is the most cost-effective step a homeowner can take.
Repair or Replace: The Actual Criteria
The decision to repair or replace a decayed member depends on four practical criteria: how much sound section remains, where the decay is located, whether the water source can actually be closed, and how the two costs compare once you account for access and labor. A member that has lost only 10 to 20 percent of its section to decay, with the sound wood concentrated at the bearing points where it carries load, can often be repaired. The simplest repair is sistering: bolting or nailing a new joist, beam, or other member alongside the damaged one, so that the two share the load. Sistering is effective because it restores stiffness and strength without requiring removal of the decayed member, which saves access and demolition costs. It works best for joists and beams that are not severely compromised and where the bearing points are still sound.
When decay is concentrated at a bearing point (where the joist or beam rests on the sill or rim), or when the member has lost more than 30 to 40 percent of its section, replacement is usually the honest answer. Removing and replacing a floor joist or a rim joist requires careful work, but it is straightforward carpentry. Replacement also gives you a chance to close the water path: you can install new flashing, improve drainage, or repair the roof or gutter that allowed water in. Epoxy consolidants and wood fillers have a real but narrow use. They can stabilize non-structural profiled trim (crown molding, casing, or baseboard) that is worth saving for its appearance or historical value. They are not a repair for structural members. Filler over rot in a joist or beam is not a repair; it is a delay.
A good contractor will quote both options where both are real, and will explain the trade-offs clearly. Repair is less expensive upfront but leaves the original member in place and may require periodic monitoring. Replacement costs more but gives you new wood with decades of life ahead and a chance to address the moisture problem that caused the decay. The choice depends on the extent of the damage, the cost difference, and your comfort with the result. For detailed information about specific repair scenarios, see our pages on Wood Rot & Dry Rot Repair, Floor Joist & Subfloor Repair, and Deck & Porch Repair.
Who Does What: Carpenter, Pest Operator, Engineer
Wood decay and insect damage involve several different trades, and understanding who does what will protect you from incomplete work and unnecessary expense. A licensed or registered pest control operator identifies insects, treats infestations, and documents the damage. A carpenter removes decayed or damaged wood and rebuilds the structure. A licensed structural engineer designs repairs, specifies beam sizes, and certifies that load-bearing alterations are safe. The local building department (in this case, the City of Spokane or the county, depending on your location) issues permits for structural work and inspects it to ensure it meets code. Each of these professionals has a specific scope and responsibility.
Spokane Carpentry is the carpenter. We are fully insured and a WA L&I Registered Contractor. We remove decayed wood, repair or replace damaged members, sister joists, install new beams, close water paths, and rebuild decks, siding, trim, and framing. We work from your pest inspection report if insects are involved, but we do not treat insects or apply pesticides. If your repair involves removing or altering a load-bearing wall, replacing a beam, or significantly changing the structure, the work commonly requires a licensed structural engineer to size the new member and specify the repair, as well as a permit from the building department. We can help you understand whether a permit is needed and can work closely with an engineer if your project requires one. We can also help document damage for an insurance claim. The division of labor exists because each trade requires specific knowledge and licensing. When each professional stays in their lane and does their job well, you get a repair that is safe, complete, and built to last.