The basement has made it clear: it’s not going to cooperate without a fight. Right now the score feels like Basement: 3, John and Sherry: 1. Fortunately we love a challenge. Here’s an update on our major underground overhaul and how we plan to turn a damp, spider-filled storage dungeon into a useful, organized space.
Many readers asked for more detailed, behind-the-scenes information — not just a source list and budget breakdown, but our actual decision-making process: how we prioritized functions, sketched a workable layout, and handled the obstacles that popped up. We’ll share every step of the conversion from cobwebby cellar to finished, functional storage room where we can safely keep extra furniture, bikes, seasonal decor, and anything else we don’t want covered in mold.
First, some context: the basement sits directly under the sunroom off the back of the house and is accessed by a small brick staircase. At roughly 19′ x 13′ it’s one of the largest rooms in the house, but that’s where the positives mostly end. This space has multiple problems: periodic flooding (we’ve seen inch-deep puddles after heavy storms), an overwhelming spider/web situation, and pervasive mildew on walls, floors, and stored items. We also have an awkwardly placed water heater, a radon mitigation pipe, a small trap door leading to a crawl space, and only two tiny windows that let in very little light. Not an ideal starting point.
Because the room has its own exterior entry, it will likely remain a non-living, utilitarian space. Our goal is to turn it into highly functional, attractive storage — more of a built-in look than a jumble of wire shelves and bowed boards. Before we could finalize layout and storage systems, we had to solve the biggest issues that made the room unusable: moisture and mildew. Both problems stem from trapped moisture in the underground space.
After researching the issue, we identified three essential steps to correct the water and mildew problems:
- Eliminate existing mildew completely.
- Seal the cinder-block walls and concrete floor so the raw stone can’t absorb water during storms.
- Install a reliable energy-efficient dehumidifier to stabilize humidity and prevent mildew recurrence.
The most recommended sealing product we found was Drylok, a heavy-duty masonry sealer that goes on thick and, after two coats, prevents moisture from passing through concrete and cinder block for many years. It’s not inexpensive, but it’s one of the few solutions that promises long-term protection against seepage.
We were fortunate to have a DIY budget that helped cover materials. To seal this basement properly we needed nine gallons of Drylok at roughly $25 per gallon — a meaningful expense, but doing the work ourselves saved a significant amount compared to hiring professionals to caulk and apply the product. By filling visible cracks with exterior caulk and concrete filler and rolling two coats of Drylok ourselves, we likely saved well over a thousand dollars.
Preparation required clearing the room and removing fixtures that interfered with a clean seal. We took down an extra light fixture, a quirky metal tool organizer, and old shelving brackets so we could Drylok behind them and create a seamless finish. Then we patched cracks and moved on to the messy but necessary sealing work.
We learned a few important things about Drylok along the way. It comes in latex-based and oil-based formulations. The latex version is available only in white and has a lower odor than the oil-based variety, which comes in several colors and is much stronger-smelling. Because we were cautious about fumes, we used the latex-based product for the first coat and invested in high-quality respirators for protection. That was a wise choice; even the lower-odor formula is potent when applied in an enclosed space.
Shortly after our first coat went on, mildew began showing through as small tan spots. Even after spraying walls with a bleach-and-water solution and scrubbing, the mildew reappeared beneath the Drylok. It became clear that while the latex coat helps block external water, mildew already embedded in the surface can push through or reactivate.
To address this, we chose an oil-based Drylok tinted beige for the second coat. This option offers better hiding power, eliminates the starkness of bright white in a windowless room, and—according to experienced suppliers—may provide an even stronger barrier against future moisture and mildew when used alongside proper humidity control. We also considered long-term maintenance: painting over Drylok can prevent future reapplication of the product, so choosing a tinted sealer that both protects and looks finished felt like the right compromise.
We plan to paint the ceiling the same beige for a cohesive look and finish the floor with a chocolate-colored floor paint we have on hand for definition and durability. Once the final coats dry and the space is fully sealed, the last step will be installing an Energy Star-rated dehumidifier to maintain stable humidity and prevent mildew from returning.
If you’ve dealt with basement moisture, flooding, or persistent mildew, we’d love to hear what worked for you. Any tips or experiences with sealing, mildew removal, or dehumidification are welcome as we move forward. Fingers crossed we can even the score with this basement soon.
