Crawl space waterproofing is about water you can see — standing water, mud, water running in after a storm — as distinct from encapsulation, which deals mainly with humidity. Most Birmingham crawl spaces with a water problem need both, but in a specific order: get the liquid water under control first, then seal and dehumidify.
Where the Water Comes From
Surface water is the most common source and the cheapest to fix. Downspouts that discharge at the corner of the house, ground that slopes back toward the foundation, patios and driveways pitched the wrong way, and mulch beds built up above the level of the siding all deliver rainfall straight to the foundation wall.
Subsurface water matters on Birmingham’s slopes. On a hillside lot, water moves through the soil downhill and arrives at the uphill wall of your crawl space. That is why one wall is often wet and the others are dry.
Plumbing leaks are worth ruling out before spending on drainage, particularly slow supply-line leaks that never show upstairs.
The Order of Work
Exterior first, because it is cheaper. Extending downspouts six to ten feet from the house, correcting the grade to fall away from the foundation for the first several feet, and clearing or installing a footing drain solve a meaningful proportion of crawl space water problems for a small fraction of what interior work costs.
Interior drainage where water is still arriving. A perforated pipe in a gravel trench around the interior perimeter, below the level of the crawl space floor, collecting water and carrying it to a sump.
A sump pump with a sealed lid and a discharge run well away from the house. Discharging a sump next to the foundation simply recirculates the problem.
A vapor barrier over the top once the space is drying, and dehumidification to hold it there.
What Not to Do
Do not add more vents. It is an intuitive response to a damp crawl space and in our climate it makes the humidity worse for most of the year.
Do not lay plastic over standing water and consider the job done. The water is still there and now it is invisible.
Do not run a sump discharge into a sanitary sewer. It is against code in most jurisdictions and can back up into the house.
Realistic Expectations
Waterproofing a crawl space does not mean water will never appear again in an extraordinary storm. It means the system is designed to collect and remove it before it sits. On a house with a genuine hillside water problem, expect the pump to run — that is it working, not failing.