DRIFTFORM

Reference

Waterproofing approaches compared.

Three comparisons that come up in every quote. Each one answers the question directly, then sets out the differences — so you can read a recommendation and know why it was made.

Comparison 01

Polyurethane injection vs. excavation — which is right for a leaking basement?

Polyurethane injection seals a leaking basement from the inside without excavation; excavation replaces the external membrane from the outside but requires access, cost, and disruption. Injection is the first option when the leak is through cracks or joints and the building is occupied.

InjectionExcavation / Replacement
AccessInternal — no excavation requiredExternal — requires digging to the foundation
DisruptionMinimal — work is done inside, building stays occupiedSignificant — excavation equipment, noise, dust, access restrictions
CostLower — targeted repair of specific cracks and jointsHigher — full membrane replacement plus site restoration
Best forActive leaks through cracks, joints, and penetrations in occupied buildingsBroad membrane failure where the external system has degraded entirely
LimitationAddresses specific failure points, not a failed membrane systemRequires external access — not possible on boundary walls or shared structures
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Comparison 02

Negative-side vs. positive-side waterproofing — what's the difference?

Positive-side waterproofing is applied to the exterior face of a wall or slab — the side directly exposed to water. Negative-side waterproofing is applied to the interior face — the side opposite the water. Negative-side is used when external access is not possible, such as basements, lift pits, and retaining walls on boundaries.

InjectionExcavation / Replacement
Application faceInterior (negative) — opposite the water sourceExterior (positive) — directly facing the water
When to useNo external access — boundary walls, shared structures, below-grade basementsExternal access available — new construction, full renovation
How it worksSeals the interior face against water pressure pushing through the substrateStops water before it enters the substrate
LimitationSubject to hydrostatic pressure — the membrane must bond to a sound substrateRequires excavation and access to the exterior face
Best forLift pits, basements, retaining walls, planter boxesNew builds, full external remediation
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Comparison 03

Membrane replacement vs. polyurethane injection — when is each appropriate?

Polyurethane injection targets specific failure points — cracks, joints, and penetrations — without removing the existing membrane. Membrane replacement removes and reinstates the full waterproofing system. Injection is appropriate when the failure is localised; replacement is necessary when the membrane has failed broadly.

InjectionExcavation / Replacement
ScopeTargeted — seals specific cracks, joints, and penetrationsFull — removes and reinstates the entire membrane system
When appropriateLocalised leaks through identifiable failure pointsBroad membrane failure, delamination, or systemic degradation
DisruptionLow — no demolition of finishes or tilesHigh — tiles, screed, and membrane removed and reinstated
CostLower — targeted repairHigher — full system replacement plus finishes
LifespanSeals the failure point for the life of the surrounding structureNew membrane system with full warranty lifespan
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Not sure which approach applies?

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