How To Remedy Subfloor Water Damage in Your Home’s Basement

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The American Society of Home Inspectors estimates that 60 percent of US homes have wet basements caused by everything from rain runoff to leaky pipes.

This issue is more than a simple nuisance because it can ruin everything in your finished basement or damage the subfloor of the level above. You don’t need a large leak to get enough moisture to buckle flooring or spawn mold, and even if you’re careful about cleaning up quickly, you can end up with some serious subfloor water damage.

When you have a burst pipe or storm flooding, it can take days to recover. Even then, there might be undetected issues below the flooring where you can’t see water collecting.

Remedying the situation is a big project that should be taken on as quickly as possible. The longer that water sits there, the more likely there is to be damage and the more extensive it will be. The wetness in the subflooring can wick up the framing and walls to cause even more damage.

Let’s take a look at the signs you have damage, how to make subflooring repairs, and how to prevent issues in the future.

Basement Subflooring

Your basement subflooring serves to provide a flat level surface for the floor and to keep moisture at bay. It’s the structural bit that spans floor joists and is hidden beneath finished flooring material. It’s usually made from softwood boards, plywood, and oriented strand board.

Because wood is naturally porous and absorbs moisture, it is often installed over mini-joists in the basement that allows it to sit above the concrete pad. You can also install a vapor barrier to protect the flooring from damp, usually a sheet of plastic taped over the concrete pad.

Subflooring should last as long as the house itself, but if it is damaged or defective, that lifespan is severely shortened. The water that damages it usually comes from misdirected rainwater and leaking plumbing.

Detecting Damage

If your floor looks just fine, how can you tell if there are water-damaged sub-floors underneath? Musty odors, stains or wet spots, and peeling paint are just a few signs you’ve got water damage in your basement.

When you walk across the floor, you might notice it feels spongy underfoot or bounces, a sure sign the subfloor is holding water or starting to rot. Cupping boards, mold growth, and discoloration can also be the flooring telling you there’s a problem underneath.

How to Repair

Taking steps immediately can keep the problem from becoming a disaster. Your first step is to stop the water causing the issue. You need to find the source and fix it before you start work on the floor.

Your next big step is to dry the floor out as soon as you can. You can use a dehumidifier to get water out of the air, and place fans around to circulate the air in the space. The faster you can dry the floor out, the sooner you’ll be able to determine how to proceed with the repair.

Once you get started with demoing the floor, you need to follow the path of water destruction until you uncover the whole thing. Water can travel quite a distance and even damage other surfaces in contact with the floor like the wall framing and sheetrock.

After you’ve uncovered the damaged material, you’ll remove it by cutting it out, going beyond the damage until you get to solid structural framing. Venting the area after removing the damage allows every nook and cranny to dry thoroughly before you install replacement material.

You’ll need to check the support framing as well to add or replace pieces there as needed. You want a solid base for the new subfloor. Measure and cut your plywood or OSB, leaving a gap between the new and old pieces for expansion, then fasten it down to the floor framing.

Does It Need to Be Replaced?

Not all water damage automatically requires replacing the subfloor. If you can start drying the space out immediately after the water gets in, you might be able to avoid replacement. The problems start when the wood sits soaked long enough that it develops mold and rot.

Once you remove moisture from the subfloor, you’ll be able to tell if the material has been severely damaged or if it’s salvageable. Mold and rot call for replacement, and that can be the most time and cost-effective way to deal with the situation.

Preventing Damage

The most common causes of a wet basement are rainfall and melting snow, but rising groundwater is also a culprit. These are less easy to identify than obvious plumbing emergencies like burst frozen pipes or leaking drain lines.

With a chronic issue, you need to figure out when of the three most common moisture issues you have – condensation, runoff, or subsurface seepage.

Condensation shows up as wet spots or puddles on the basement floor and walls. It happens when moist warm air hits the cool foundation walls or uninsulated pipes. You can install a dehumidifier to keep the space dryer, turn up the heat in colder months, or even add a waterproof coating to the walls.

Runoff is when rain or melting snow aren’t routed away from the house and foundation, a common cause of damp under the house or in the basement. If you notice the moisture right after a storm, this is the most likely cause of your issue. You want to ensure the ground outside slopes away from the house, and the downspouts aren’t pooling water near the foundation.

With subsurface water, you see the same kinds of issues as with rain runoff, but it happens all the time and not just after a storm. This type of issue likely needs a professional to deal with it. A sump and sump pump are common solutions deployed, along with exterior drains running alongside the foundation outside.

Deal With Subfloor Water Damage Immediately

Spongy floors and musty odors are sure signs there’s water damage underfoot in your basement. Subfloor water damage creates an unhealthy atmosphere and is guaranteed to ruin any type of flooring you put in the space. Replacing water-damaged subflooring and correcting the source of the moisture can save you money and hassle and maintain your home’s value.

If you’re concerned about the state of your basement or a possible rotted subfloor, contact us to schedule an assessment for a specialized waterproofing solution. Our expert team can give you peace of mind knowing your basement is secure and dry.