When snow melts and the ground is still wet or frozen, meltwater can run toward a foundation and find low entry points. A basement that takes in water during a thaw needs its walls, floor and entry points checked, and the moisture measured before anything is closed up. Ankeny Water Damage Restoration takes water damage calls at any hour in Ankeny and the surrounding area.
Key takeaways
- Meltwater runs over ground that cannot absorb it, and it can reach a basement through the same low entries as rain.
- Soil that stays saturated after a thaw keeps moisture moving into the foundation, even when the surface looks dry.
- The first check is outside: the grade, the downspouts, the window wells and any walkout door on the low side.
- Inside, a moisture reading on the wall base and the floor shows what a dry surface cannot.
- A thaw that leaves water in the basement is still a water loss, so it should be measured and recorded like any other.
Why does a thaw bring water into a basement?
Snow and ice hold water in one place and release it all at once. When the ground is still frozen or already saturated, meltwater cannot soak in, so it runs across the surface toward the lowest point. That point is often the foundation of a house, and the water finds the first opening it can reach.
A thaw is a different event from a steady rain. The water arrives over a shorter period on ground that may already hold moisture from earlier weather. The result can be runoff that pools against a foundation, rather than soaking gradually into the soil.
The basement is not always the first place the water shows. Water can stand outside the house for a while before it finds an entry, and the surface around the foundation can stay saturated for longer than the thaw itself. A house can take in water after the first day, once the ground has nowhere left to drain.
Where does meltwater usually get in?
Meltwater enters at the lowest openings: a walkout door, a window well, a floor drain, a crack or a joint in the foundation, and a sump that cannot keep up. Each leaves a different pattern on the floor and walls, and the crew uses those patterns to find the route.
Window wells collect snow and meltwater, and a well that is full of ice or silt cannot drain. Water then runs over the top of the well or through the window into the basement. A cover or a drain at the bottom of the well keeps the opening clear and reduces this risk.
A walkout door set low on the slope takes water at the threshold, and a floor drain can back up when the outside system is full. Foundation cracks and wall joints can let water through when the soil against the wall stays wet for a long time.
- Window wells packed with snow, ice or silt
- Walkout doors set at or below the level of the yard
- Floor drains that back up when the outside system is full
- Cracks and joints where the wall meets the floor
- A sump pit that cannot keep up with the water arriving
What should I check outside after a thaw?
Clear the snow and ice from window wells and away from the foundation if it can be done safely. Check the grade beside the house, the downspouts and the walkout door. Note where the water is pooling and where it is running toward the house. Photograph all of it before you change anything.
Look at the grade first. Snow piled against the foundation can hold water against the wall, and a low spot beside the house can collect runoff. A downspout that ends at the wall, or that is blocked with ice, can send roof water straight into the soil at the foundation.
Do not dig trenches or change the grade during a thaw without a plan. Grading and drainage repairs are for a qualified contractor, and work done in soaked ground can make the problem worse. Note what you see and keep the photographs for that contractor.
What should I check inside the basement?
Look for water on the floor, a damp line on the walls, a musty smell, soft drywall at the bottom of the wall and a sump pit that is running more than usual. Check the floor drain and the stairs for silt or wet debris. A moisture reading is the reliable check for what the eye cannot see.
Start at the lowest point and work upward. A damp patch at the wall-to-floor joint, a stain or a white mineral bloom on the concrete, or a line of silt on the wall all mark the route the water took. Note the height of each mark.
Press gently on the bottom edge of drywall and paneling. Soft board has taken on water and will not dry back to shape. Do not poke holes in the wall to test it, because a hole can let moisture in and hide the damage from the crew.
| Area | Sign to look for | Action |
|---|---|---|
| Walkout door | Water at the threshold or a wet line on the sill | Photograph it and note the height of the water |
| Window well | Ice, silt or water standing in the well | Clear it safely and photograph the well before and after |
| Lower wall | A damp band near the floor or a stain at the baseboard | Take a reading at the baseboard and a little higher |
| Floor and drain | Water pooling, silt or a drain that holds water | Keep the power off in wet areas and call for help |
| Sump pit | Running longer than usual, or water at the rim | Confirm the pump is working and the discharge is clear |
| Stored items | Water marks on the bottoms of boxes and shelves | Move items to a dry room and list each one |
When is a thaw leak serious enough to call for help?
Call when there is standing water, when the water is still rising, when the sump cannot keep up or when there is a smell of mustiness that does not clear. Call also if the walls feel soft or the floor feels spongy, because that is a sign of moisture inside the structure.
A small damp spot that dries on its own within a day is a different case from water that keeps returning after each thaw. A recurring leak points to an entry that has not been fixed, and it needs the entry found and the moisture measured.
The water damage line is answered at any hour. Explain where you see water, whether it is rising and whether the sump is running. The crew decides on the visit from that information, and it does not promise an arrival time on this page.
How is the moisture measured in a thaw loss?
A moisture meter is used on the wall base, the floor, the framing and the subfloor, and each reading is recorded with its location and its material. The first reading becomes the baseline, and each later reading shows whether the basement is drying or still taking in water.
A reading tells you more than the look of the wall. A wall can appear dry while the cavity holds moisture, and a floor can look fine while the subfloor beneath it is wet. The meter finds those moisture pockets.
Readings should be repeated at the same points on each visit. A reading that falls shows the drying is working. A reading that stays flat or rises tells the crew that water is still arriving, and it returns to find the entry.
What should I do to prevent the next thaw leak?
Keep window wells clear, check the grade beside the foundation, extend downspouts well away from the house and make sure the sump and its discharge line are working before the next thaw. A qualified contractor can look at the grade, the drains and any repair to the foundation.
Covers and drains for window wells keep the opening clear when snow and meltwater arrive. A downspout that drains onto a lawn sloping toward the house can send water back to the foundation, so the route of each downspout should be checked.
Check the sump pump and the discharge line before the thaw, and test the pump by pouring water into the pit. Make sure the discharge ends where the water will not flow back toward the house.
Plan a check of the basement a day or two after each thaw, not only once a year. A basement that looks dry on the first check can still take in water on a later day, when the ground has finished releasing what it held. Write down the readings and the dates, so a pattern shows up if one does.
Frequently asked questions
Is a thaw always a basement water problem?
No, but it can be. Meltwater can enter a basement through the same low openings as rain. Whether it does depends on the grade, the drains and the condition of the foundation, and a check after the thaw shows which applies.
Should I shovel snow away from the foundation?
Clearing snow from window wells and from the area just outside a door is a reasonable step if it can be done safely. Avoid heaping snow against the wall, and keep clear of ice. Be careful on slippery surfaces.
Can I run the sump pump continuously during a thaw?
A sump runs when water reaches its pit. If it runs constantly, check that it is working, that the discharge is clear and that the check valve is not stuck. If water still reaches the floor, call.
What if I find a damp spot that comes back after each thaw?
A spot that returns is pointing to an entry that has not been fixed. Photograph it, measure it and call. The crew can trace the route, and a qualified contractor can plan the repair.
How long should a basement stay closed after a thaw leak?
Keep it closed until the readings show the wall base, floor and framing are dry at the set level. Closing a room too soon can trap moisture behind finishes, and the crew explains when the room is ready.
Will the insurer pay for thaw damage?
That depends on the policy and on the cause of the water. Many policies treat ground water and runoff differently from sudden sources. The insurer decides the claim, and the photographs and readings from the crew are the facts it will ask for.
This guide is general information for Polk County homeowners, not a substitute for an on-site inspection. Prices are estimates. See our disclaimer.