Water in a foundation does not stay put — it wicks through concrete, rots fixings and ruins finishes. Goliath Coatings delivers below-ground foundation waterproofing across Auckland, sealing foundations and footings against ground water so the structure stays dry and sound for the long term.
How foundation waterproofing protects the structure
Below ground, concrete is under constant hydrostatic pressure from surrounding soil. Foundation waterproofing creates a continuous barrier — applied to the positive (outside) face where possible, or as a negative-side tanking system internally — that stops water migrating through the slab and walls. Get it right at build or remediation stage and you avoid damp, efflorescence and the slow damage that follows.
The systems we use
We use the right approach for the site: liquid-applied membranes that form a seamless seal around complex footings, sheet membranes for larger faces, cementitious tanking slurries for internal negative-side protection, and cavity drainage where water needs managing rather than blocking. Detailing at construction joints, penetrations and cold joints is where foundations leak, so that is where we concentrate.
New build and remediation
We waterproof new foundations before backfill and remediate existing foundations that have started to let water in. Either way we assess the water source and pressure first, then specify a system rated for the conditions — there is no single product that suits every foundation, and we will not pretend otherwise.
The products and systems we use
Foundation waterproofing is only as good as the system chosen for the conditions. On new builds we protect the structure from the positive (soil) side before backfill, using blind-side and self-adhesive sheet membranes such as Bituthene 3000 and Preprufe, Sika SikaProof A and Sika BlackSeal, with torch-on bituminous membranes over footings where a tougher layer is needed. Where we can only work from inside an existing foundation, we switch to negative-side cementitious systems like Mapei Mapelastic Foundation and penetrating crystalline waterproofing such as Xypex and Markham Aquron, which seal the concrete itself against rising damp and hydrostatic pressure. Every joint, penetration and slab edge is detailed individually.
Why choose Goliath Coatings
Below-ground waterproofing and tanking are a core specialty. On new builds we protect the structure from the soil side before backfill; on existing homes we remediate from the inside where the outside is no longer reachable — matched to the ground conditions and water table on your site. Free on-site assessment, one-business-day response, and 5-star Auckland reviews behind every job.
Foundation waterproofing FAQs
Q: Can you waterproof an existing foundation?
A: Yes — where we cannot reach the outside face we use internal negative-side tanking and cavity drainage systems to keep the space dry.
Q: What causes a foundation to leak?
A: Usually failed or missing waterproofing at joints, penetrations or cold joints, combined with ground-water pressure. We trace the source before specifying a fix.
Q: Is this different from damp-proofing?
A: Yes — damp-proofing slows moisture, waterproofing holds back liquid water under pressure. Below-ground foundations need true waterproofing.
Q: What products do you use to waterproof a foundation?
A: Typically Bituthene 3000 and Preprufe or SikaProof for new below-grade work, and Mapelastic Foundation or crystalline systems like Xypex and Aquron when an existing foundation can only be treated from the inside.
Q: What determines the cost?
A: The extent of the water ingress, whether the fix is internal or external tanking, and whether drainage needs upgrading. We diagnose the source on site — free — then quote the right system, not the most expensive one.
Q: Is the work guaranteed?
A: Yes — our workmanship is guaranteed and we install proven systems from leading suppliers. Goliath Coatings is fully insured, Tōtika accredited and Site Safe certified.