About this guide

Long Island Dry Basement Guide is an independent, hand-verified directory of basement waterproofing companies serving Long Island, New York. It was built from a Phase 2 research file dated 2026-11-03, company by company, from each company's own website, and the 20 companies were approved one by one in review on 2026-11-03.

How listings were verified

• A company's own website beats directories whenever they conflict. Directory phone numbers, addresses and license numbers were deliberately not used where they differed from the company's own site.
• License numbers appear only where the company's own website publishes one. Only 4 of the 20 companies in this guide publish a license number on their own website. The rest publish only a claim of being licensed and insured, without a number, or publish no license mention at all. A directory award is not a license, and a mold-remediation license is not a waterproofing license.
• Ratings appear only where the research file records one from the company's own site, with source and count where given. Only 4 of the 20 companies in this guide publish a rating with a review count on their own website.
• Prices appear only where a company publishes one on its own website. No company in this guide publishes a fixed waterproofing price. Ranges and discounts found on company sites are quoted in the cost guide, labeled as such, never as fixed prices for every home.
• Companies that publish no street address on their own site are marked as such. No address was invented for them. 4 of the 20 companies in this guide are service-area companies.
• Company types are labeled. Some companies in this guide are waterproofing specialists on their own site; others are foundation-repair firms, general remodelers, masonry companies, or a residential brand of a larger technical services company, and the profile states that plainly. One company is listed with a verified limitation on the systems attributed to it.
• Waterproofing is described in this guide only as water control, dryness and structural protection. No profile presents waterproofing as a benefit to personal well-being.

Featured listings

Featured listings are currently off for every company in this guide. No company paid for placement, and no company is marked as featured in the data. If a featured listing ever appears in future, it will be clearly labeled as a paid placement and will not change the verified facts in the profile. A featured label is never a quality endorsement.

Service-area companies

A service-area company serves Long Island but publishes no street address on its own site. Those companies are marked as service-area companies in this guide.

Corrections

If a fact in a profile is wrong, write to listings@longislanddrybasement.com with the correction and a link to the page on your own website that shows it. We correct verified facts against the company's own website.

Photos on this site are illustrative and do not depict any listed company's own installations.