SEMCO field notes
waterproofing guides.
Prep, application and troubleshooting for basements, roofs, showers, pools and more, written by the team that makes SEMCO.
54 articles
basementBasement Waterproofing Before Winter: A 7-Point Freeze-Thaw Checklist
A 7-point freeze-thaw checklist for basement waterproofing before winter: grading, cracks, reinforcement and a flexible membrane before the ground freezes.
Read the article
concreteHow to Waterproof a Concrete or Flat Roof Before Winter Rain
Concrete, built-up, and torch-down roofs leak differently than pitched roofs. Here's how to prep, seal seams, and coat a flat roof before...
Read the article
Is Drywall Actually Waterproof? The Myths DIYers Get Wrong
Green board, cement board, and paint don't make drywall waterproof. Here's what actually stops water, and how to seal it yourself.
Read the article
roofMetal Roof Leaking? How to Find and Seal It Before Winter Rain
Metal roof leaking when it rains hard? Here's how to find the real leak point and seal it yourself with a flexible...
Read the article
comparisonLiquid Rubber Alternatives: A Longer-Lasting Way to Waterproof
A flexible, water-based liquid waterproofing membrane is the best liquid rubber alternative. See how it compares to rubber, masonry, silicone and sheet...
Read the article
fabric reinforcementWhat Is SEMCO Fabric Reinforcement and When Do You Actually Need It?
SEMCO Fabric Reinforcement adds tensile strength at floor-to-wall joints, corners, coves, and cracks over 1/4 inch, the spots a waterproofing coating fails...
Read the article
bathroomWhat Does It Cost to Waterproof a Shower Before Tiling? 2026 DIY vs Pro Breakdown
Professional shower waterproofing runs $450 to $2,500 depending on scope. A DIY liquid membrane and fabric reinforcement costs about $150 to $200...
Read the article
basementWater-Based Membrane vs Rubber-Based Coating for Basement Walls: Which One Actually Stops Water
Comparing water-based liquid membrane and rubber-based coatings for basement waterproofing: odor, UV exposure, cure time, and which one belongs on an exposed...
Read the article
deckWood Deck Waterproofing Membrane: The Complete Guide Before Fall Rains
Sealers and stains don't stop deck rot at the ledger board and joints. Here's how a liquid waterproofing membrane actually keeps a...
Read the article
bathroomShower Waterproofing Membrane: What Actually Stops Leaks Behind the Tile
Grout isn't what stops a shower leak. See the 3 spots where showers actually fail, and how to waterproof them with a...
Read the article
basementIs Black Mold on Concrete Basement Walls Actually Dangerous? What to Check Before You Waterproof
Dark staining on a basement wall isn't always toxic black mold. Here's what CDC and EPA guidance actually says, how to check...
Read the article
troubleshootingWhy Some Waterproofing Membranes Smell So Strong (and How to Tell If It's Actually a Problem)
A strong tar or kerosene smell after waterproofing usually means an asphalt-based or rubberized coating was used. Here's what causes it, whether...
Read the articleNeed a hand?
Not sure what your project needs?
Pick your project and get the full kit: prep, membrane, reinforcement and topcoat, sized to your area.