CSU Extension advises three prevention steps for subterranean termites: keep wood off soil, remove waste wood from around the building, and seal foundation and plumbing cracks. This checklist turns those steps into a room-by-room and outside-in list a homeowner can work through in a weekend.
Key takeaways
- Keep wood off soil: lift steps, posts and fence boards that touch the ground.
- Remove waste wood: firewood, offcuts and pallets should not sit against the foundation.
- Seal cracks in the foundation and where pipes and cables enter.
- Manage water: extend downspouts, keep mulch below the siding and check grading.
- Clear the crawl space vents and check for standing water.
- Check again after heavy rain, a freeze or any change to the grade.
Step 1: Walk the outside and mark wood on soil
Start at the front and walk around the house, marking each piece of wood that touches soil, including steps, posts, fence attachments and decking close to the ground.
A wood step that sits directly on soil is a direct route for subterranean termites, which need soil or moisture to move between the ground and the wood. Mark each one with a stake or a strip of tape, and note its position on a simple sketch of the house. A sketch makes the next walk faster and gives the technician a clear picture.
A fence attached to the wall is easy to miss because it looks like part of the yard. Check where the fence meets the house, whether the posts are in soil and whether the boards sit close to the ground. Those contacts are the same risk as a step, and they are fixed the same way.
Step 2: Clear the waste wood
Remove firewood, scrap lumber, pallets and stored boxes from against the foundation. CSU lists waste wood as something to remove, because it gives termites food and shelter close to the building.
Firewood is the most common item. Move it to a rack away from the house, raised off the ground, and keep the space between the pile and the wall clear. A pile against a garage or a house wall is protected from the weather and kept damp by the soil beneath it.
Scrap lumber, pallets and cardboard boxes are the same kind of item on a smaller scale. Check the crawl space and the basement for stored boxes and move them off the floor and away from the walls. A clear space is also easier for the inspector to reach.
Step 3: Seal the cracks
Seal the foundation cracks and the gaps around pipes and cables that enter the house. CSU names those cracks as access routes for termites and moisture.
A hairline crack in a concrete foundation can be sealed with a flexible product suited to the surface. A wider crack that runs through the wall may need a repair that a technician should assess. Mark each crack on the sketch and note whether it is a surface crack or one that goes through the wall.
Gaps around plumbing and cable penetrations are sealed with a material that suits the joint. A foam product should be trimmed and covered where it is exposed to sun, because foam breaks down under ultraviolet light.
Step 4: Manage the water
Extend the downspouts away from the wall, check the grade so it slopes away from the house, and keep planting beds and mulch below the lowest course of siding.
A downspout that empties at the foundation keeps the soil damp against the wall. Extend it several feet, or fit a drain line that carries the water away. Check the grade on each side of the house and note any low spot where water collects.
Mulch and planting beds against the wall hold moisture. Keep the mulch below the siding, leave a small gap between the bed and the foundation where possible, and water away from the wall. A garden bed that is watered on a timer should be checked so it does not keep the soil wet at the wall.
Step 5: Check the crawl space
Check the crawl space or basement for standing water, damp wood, clear vents and any soil built up against the foundation inside.
Standing water in a crawl space is a sign that the drainage or the grade needs work. Note where the water sits and whether it has a clear source, such as a leak or a gutter that overflows near the wall.
Crawl space vents should be clear of snow, soil and debris. A vent blocked by a pile of soil or snow lets moisture build up in the space. Keep the vents clear, and check after heavy snow.
Step 6: Keep the list and check again
Write down what was done and when, and check the list after heavy rain, a freeze or any change to the grade. A prevention plan decays if the mulch is piled back up or the downspout is pushed against the wall.
A short written list and a set of photos make the next check quick. Note the date and the condition of each item. A homeowner who keeps the list can see which items keep coming back and which need a permanent fix.
If a sign of termites appears after the work, book an inspection rather than assuming the prevention failed. The sources do not promise that prevention ends all risk, and an inspection is the way to know what is present.
How do I check the foundation from the outside?
Walk the perimeter and look for cracks, gaps around penetrations, soil piled against the wall and any wood in contact with the foundation or the soil. Use a flashlight on the lower courses of the siding and the sill.
Start at one corner and move around the house in a single direction, so nothing is missed. Note each crack by its length and direction. A crack that runs diagonally through a block wall may indicate movement, and that is a matter for a professional, not a sealing job.
Look for the places where a pipe, a cable or a gas line enters the foundation. The gap around each one should be sealed, and the seal should be checked for cracking in the spring.
What should a homeowner do after a heavy storm?
After heavy rain or snow, check the low corners of the lot, the downspouts, the crawl space vents and the soil at the foundation. Note any new standing water, washed soil or blocked vent.
Storms move soil and open water paths. A low corner that held water after the last storm may now have a channel running toward the wall. The fix is often a small regrade or a longer downspout extension, and it is worth doing before the next storm.
Blocked vents are easy to miss. After a heavy snow, a vent may be buried in a drift, and the crawl space can then hold moisture. Clear each vent once the snow melts and check the space for damp.
How do I keep the checklist up to date?
Put the checklist on a calendar with a set date each season, and update it when something changes, such as a new deck, a new fence or a renovation. A checklist that is not kept up loses its value quickly.
A seasonal date in spring and autumn is enough for most homes. Use the same order each time, so the walk is quick and nothing is missed. A new item, such as a shed or a raised bed, goes on the list the first time it appears.
The checklist can also be shared with a technician. A copy with the items marked and dated gives the inspector a clear starting point, and it shows which items were already done.
When should I stop doing it myself and call a professional?
Call a professional when a sign of termites is seen, when a repair involves structural wood, or when the crawl space has standing water that you cannot trace. The checklist does not replace the inspection.
A mud tube, hollow wood or swarmers are signs that need an inspector. The inspector is also the right person to decide whether a sill or a joist needs replacing, because that work affects the structure and should be done to a standard.
A crawl space with standing water that keeps returning needs a drainage assessment. The checklist can show where the water sits, but the fix may need a contractor or an engineer, and the report will say which.
Step 7: Record what the house needs next
Finish the walk by writing a short list of the items still open, in order of effect, with a date for each. The list is the homeowner’s own plan and it tells any technician what has already been dealt with.
Items that reduce access to the wood or the foundation come first: wood on soil, waste wood at the wall and cracks that run through the foundation. Items that only tidy the lot come last. A list in that order makes it clear where the time and money should go.
The list also helps a technician who visits later. An inspector who sees a dated list can check whether the items were done, and can focus the inspection on what has changed. A homeowner who keeps the list for each season builds a record that is worth more over the years than any single visit.
Frequently asked questions
Do I need a professional for prevention?
Most of the steps can be done by a homeowner. A technician is useful for the foundation survey and for any repair involving structural wood.
How often should I check?
A seasonal walk is a sensible default, with a check after heavy rain or a freeze. The first check after the work is the most important one.
Does prevention replace an inspection?
No. Prevention reduces the conditions termites need. An inspection finds what is already there, and it is the step to take when a sign appears.
Is mulch always a problem?
Not in itself. The concern is mulch piled above the siding line or held in a bed that keeps the foundation wet. Keeping mulch below the siding and away from the wall is the practical rule.
Should I use treated lumber for a repair?
A repair to wood close to the soil should use material suited to that exposure, and the technician or a builder can advise on the right grade. The checklist does not recommend a specific product.
What if the crawl space vent is in the snow?
Clear the vent once the snow allows and check the space for damp. A vent that stays blocked for a season can let moisture build up in the space.
Sources
This guide is general information for Boulder County homeowners, not a substitute for an on-site inspection. Prices are estimates. See our disclaimer.