If you're dealing with a foundation wall that keeps failing interior patches because water is entering from outside, Arrow Tight Waterproofing's Exterior Waterproofing specialists are ready to diagnose it right and fix it for good — not just patch the symptom.
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We call in utility locates before any excavation begins, protecting buried gas, water, and electrical lines near your foundation.
Most exterior jobs are scheduled within one to two weeks of the initial inspection, weather permitting.
If footing depth turns out deeper than initially assessed once we dig, we stop and confirm any price adjustment with you in writing first.
Exterior footing drain tile is placed at the base, tied to daylight or a sump, completing a full envelope rather than a partial fix.
We diagnose before we quote, so the Exterior Waterproofing scope you approve is built around your property, not a generic package.
We excavate along the affected foundation wall down to the footing, exposing the full wall face so the existing damp-proofing or bare concrete can be properly treated rather than patched from the outside surface only.
Excavated soil is staged separately for clean backfill, and nearby landscaping is protected during the dig. That level of detail is what keeps an exterior membrane sealed for decades, not just a few seasons.
📞 Get a Free Quote →A minimum 60-mil rubberized asphalt or elastomeric membrane is applied directly to the cleaned foundation wall, with detailing at every penetration, tie-back hole, and form-tie point where water commonly finds a path.
This membrane is rated to resist liquid water under sustained hydrostatic pressure, unlike standard builder-grade damp-proofing. We treat this as core to the job, not an optional upgrade tacked onto the excavation.
📞 Get a Free Quote →A dimpled drainage board is installed over the cured membrane, creating an air gap that channels water down to the footing drain instead of pressing directly against the wall.
This layer significantly reduces the hydrostatic load the membrane itself has to resist over time. That level of detail is what keeps an exterior membrane sealed for decades, not just a few seasons.
📞 Get a Free Quote →New perforated drain tile is laid in a gravel bed at the footing level, routed either to a gravity daylight point or tied into your interior sump system, collecting groundwater before it can reach wall height.
This is the same footing drain specification required in new residential construction, retrofitted to an existing foundation. Cutting this corner is exactly how a foundation ends up back on a repair list five years later.
📞 Get a Free Quote →Backfill uses clean, well-draining fill rather than the original excavated soil where possible, and final grading slopes away from the foundation at the standard 6 inches over the first 10 feet.
Correct grading prevents the surface water problem that caused the original issue from simply recurring above the new waterproofing. That level of detail is what keeps an exterior membrane sealed for decades, not just a few seasons.
📞 Get a Free Quote →Call +1-866-476-1348. Exterior waterproofing is usually recommended after interior fixes haven't held, so let us know what's already been tried.
We schedule an on-site exterior assessment in Islip typically within a week, coordinated around dry-weather windows for accurate evaluation.
The technician measures affected wall footage and footing depth, checks existing damp-proofing condition, and quotes a fixed price for the full excavation scope.
Once approved, our crew excavates, applies membrane and drainage board, installs footing drain tile, and backfills — with a written warranty on the completed system.
"Had efflorescence staining getting worse every year and two different interior patches that didn't hold. Full exterior excavation with the rubber membrane finally solved it — three years now with zero staining returning.Finally addressed at the actual source."
"House was built in the 70s with what turned out to be basic damp-proofing, not real waterproofing. They excavated, applied the proper membrane and drainage board — completely different level of protection now.Finally addressed at the actual source."
"Water kept coming through the same section of foundation no matter what interior fix we tried. Turned out to be an exterior grading and membrane failure. Fixed at the source, hasn't come back since.Worth the excavation, no question."
"Excavation crew was careful around our landscaping and utility lines, which we appreciated given how much digging was involved. Backfill and grading looked better than before they started.Worth the excavation, no question."
Our Exterior Waterproofing coverage spans Islip, NY, with the same certified standard applied whether your property is in Islip or just outside it.
