After The Storms: How This Winter’s Heavy Rain Affects Termite Risk Under Your Home

This winter’s storms and king tides soaked Bay Area homes. Learn how heavy rain affects crawlspaces, slabs, and termite risk, and what Good Sense Termite checks during post storm inspections.

The Storms Are Gone, The Moisture Is Not

This winter brought heavy rain, king tides, and flooding to parts of the Bay Area, especially low lying and coastal areas in Marin, Sonoma, Alameda, San Mateo, and San Francisco. Some roads flooded, creeks spilled over, and water pushed into places that usually stay dry.

Now the sky looks calmer. The headlines have moved on. But under many homes, the water left a mark.

Even a few days of:

• Standing water in a crawlspace

• Saturated soil around a foundation

• Overflowing planters and raised beds

can shift conditions enough to matter for termites and fungus.

This post explains what heavy rain does to the areas you rarely see, what to watch in the next few months, and how a post storm termite inspection helps you sort “normal drying” from “real problem.”

What Heavy Rain Does Under A Raised Foundation

If you have a crawlspace, winter storms do more than make the soil damp.

1. Standing Water And Long Term Damp Soil

After big storms, we often see:

• Puddles or full pooling under parts of the house

• Soil that stays wet for weeks instead of days

• Piers and posts with dark water lines partway up

Why this matters:

• Subterranean termites love moist soil and sheltered routes

• Wood that stays damp is at higher risk for fungus and decay

• The combination of soft wood and termite activity is where repair costs grow

A brief wet spell that dries quickly is one thing. A crawlspace that holds water or never dries out on one side is another.

2. Moisture Wicking Into Wood

When water sits near:

• Sill plates

• Joist ends

• Posts that contact or sit close to soil

it can wick into the wood. Over time, that creates:

• Dark staining and surface fungus

• Soft or friable wood

• Easier entry points for termites

The damage may not show on your floors yet. It often starts where you would only see it from the crawlspace.

3. Blocked Or Overwhelmed Vents

Heavy rain often comes with:

• Wind blown debris

• Shifting soil

• Makeshift flood barriers

Crawlspace vents can end up:

• Blocked by mud, leaves, or plastic

• Partially buried by soil or bark

• Trapped behind temporary barriers that never get removed

Less ventilation means slower drying. Slow drying means more time in the “perfect for termites and fungus” range.

What Heavy Rain Does Around Slabs And Foundations

Even if you have a slab, storms change the way water and soil interact with your structure.

1. Raised Soil And Landscaping Creep

Big storms move material. You may end up with:

• Soil washed against siding or stucco

• Mulch that used to be neat now pressed up to the wall

• Planter beds that quietly raised their grade after you added more soil

Why it matters:

• The visible gap between soil and wood disappears

• Subterranean termites have a shorter path from ground to structure

• Moisture can reach areas that used to stay dry

2. New Cracks And Gaps

Storms can:

• Erode soil near patios and walkways

• Open small gaps where slabs meet foundation walls

• Shift small retaining features you never think about

These changes can become:

• Hidden termite highways

• New spots where water rests against concrete, then framing

You might only notice them as a slightly different line or a hairline crack. To termites, it is an access point.

Short Term: What Homeowners Can Check Right Now

You do not need special tools to do a basic post storm check.

Outside Around The House

Walk the perimeter and look for:

1. Soil against siding or stucco

   • Can you still see foundation or stem wall

   • Has soil, bark, or gravel climbed higher since the storms

2. Planter boxes and raised beds

   • Is soil now level with or above the weep screed

   • Are boxes pressing directly against the wall

3. Downspouts and drainage

   • Are downspouts flowing away from the house, or into a puddle by the foundation

   • Did storm drainage carve channels that now send water toward the structure

4. Concrete and walkways

   • Any new cracks at the edge where slab meets wall

   • Any spots where water still pools days after rain

If something looks different on the storm facing side of the house, make a note. That side often tells the story first.

If You Have A Crawlspace

Only go under the house if it is safe and you are comfortable. If you do, a few things to check:

• Any standing water, even shallow

• Mud lines on piers or posts that show previous water level

• Wood that looks dark, fuzzy, or soft near the bottom

• Vents that are blocked or buried from the outside

If there is more than light dampness, or if you see both water signs and old damage, it is a good time to call for an inspection.

Medium Term: Signs To Watch Over The Next Few Months

Storm related moisture does not always show itself right away. In the next season or two, keep an eye out for:

• New soft spots in floors, especially above low crawlspace areas or close to the edge of the slab

• Fresh cracking at baseboards or door frames on the storm facing side of the house

• Doors or windows that start sticking in one part of the home but nowhere else

• Musty smell in certain rooms, closets, or under stair storage after rain

• Swarmers or wings inside a few months after heavy rain, especially near sliding doors, baseboards, or window sills

None of these prove termites by themselves. Together with known moisture issues, they are strong reasons to bring a licensed inspector in.

How Termites Respond To Wet Winters

Heavy rain does not “create” termites, but it changes the game.

• Subterranean termites often become more active in moist soil

• Wet wood and soil can support expansion of existing colonies

• Saturated ground can cause termites to shift routes, sometimes closer to structures

After storms, we often find:

• New or expanded mud tubes on foundation walls and piers

• Activity in areas that had been dry or quiet in earlier years

• Hidden damage where long term moisture and termites have worked together

This is why a wet winter, especially following a period of drier weather, is a good time to reset your understanding of what is going on under the house, not just assume last year’s report still holds.

How A Post Storm Termite Inspection Helps

A good inspection after heavy rain does more than check for insects. It connects moisture, soil, and structure.

At Good Sense Termite, post storm inspections focus on:

• Crawlspaces

  • Signs of standing water or long term dampness

  • New mud tubes, especially on piers and lower framing

  • Ventilation issues and earth to wood contact

• Perimeter and grading

  • Soil levels around the structure

  • Planters, decks, and steps that changed function during storms

  • Cracks and joints that might be new access paths

• Interior clues

  • Areas where soft floors, cracks, or staining match what we saw outside or underneath

  • Repeat rooms that have had “dry rot” or repairs in the past

We then explain:

• What is normal for a wet season

• What looks like a developing risk

• What is active termite or fungus damage that needs attention now

For Bay Area homes that are not in active escrow, we provide inspections at no cost.For homes in escrow, we offer fee based inspections that meet real estate standards.

FAQ: Storms, Moisture, And Termite Risk

Q: Is one big storm enough to cause termite problems?

One storm rarely causes a full infestation by itself, but it can set the stage. If water sits under or around the house or soil levels change, existing colonies may expand or shift.

Q: My crawlspace had standing water but it dried. Do I still need an inspection?

If water was brief and there is no history of damage, you may be fine. If water sat for a while, or if you already have a history of “dry rot” or floor issues, an inspection is a smart step.

Q: Can I just add more dirt or bark to cover muddy areas by the foundation?

That often makes things worse. Raising soil against siding or stucco can create an easy bridge for termites. It is better to adjust drainage and keep soil below the foundation line.

Q: I saw swarmers inside after the storms. Does that mean I have major damage?Not automatically, but it does mean termites are present. The important step is to find out which type they are and where they are coming from. That is what an inspection is for.

Final Thoughts: The Storms Pass, The Structure Stays

Storms move through in a few days. The effects on soil, crawlspaces, and framing can last much longer.

You do not need to panic every time it rains, but after a winter of heavy downpours and flooding, it makes sense to ask:

• Where did the water actually go

• How long did it stay

• What did it touch on the way

If you want real answers about how this winter treated the hidden parts of your home, we are ready to look.

Schedule an inspection with Good Sense Termite. We will check the places storms like to test first, then explain what it means for your home in clear language.

It's just Good Sense.