Where water actually gets in
On a roof, it is almost never the field of shingles. It is the valleys, the flashing around a chimney or a wall, and the membrane under the eaves where extra protection matters even in a climate that rarely sees ice, because that same membrane handles wind-driven rain. On a foundation or a crawl space, it is grading that slopes toward the house instead of away from it, and gutters that dump water right against the footing instead of carrying it off.
We treat waterproofing as tracing where water wants to go and giving it a path that is not through your building.
Roof-level waterproofing
Every valley and every eave on a roof we work on gets a self-adhering waterproof membrane before the underlayment goes down, because those are the two places water concentrates fastest in a heavy Mississippi downpour. Flashing at chimneys, walls, and skylights is bent and installed so water sheds over each layer rather than getting trapped behind it.
On a flat or low-slope section, which shows up on some commercial buildings and additions around Jackson, a membrane roof system replaces shingles entirely, since standard shingles are not built for a pitch that shallow.
Below the roofline
Foundation waterproofing starts with grading and gutters before it gets to any coating or membrane on the wall itself, because no waterproof coating outperforms water that is being directed straight at the foundation by a downspout with no extension. Once drainage is corrected, cracks get sealed and, where needed, a membrane or coating goes on the exterior wall below grade.
Crawl spaces in older Jackson homes often have no vapor barrier over the dirt, which pushes humidity straight up into the floor framing. A proper vapor barrier is one of the cheapest waterproofing fixes available and one of the most overlooked.
Humidity as its own problem
Mississippi humidity does damage even without a storm involved. Poorly ventilated attics can drip condensation onto roof decking from the inside during the hottest, most humid stretch of summer, which looks exactly like a roof leak but has nothing to do with the shingles. Fixing that means correcting ventilation, not chasing a leak that does not exist on the outside of the roof.