Wet area waterproofing after a tiling dispute
Six months after handover, a homeowner reports efflorescence and loose tiles on the shower recess floor of an upstairs bathroom. The builder's records show the waterproofing was applied by a subcontractor who held a current licence, and a waterproofing certificate was issued. However, the file contains no photographs of the membrane before tiling and no record of a flood test. The subcontractor has since ceased trading. The homeowner has obtained a report from an independent consultant stating that the membrane terminates short of the shower waste and that there is no upturn at the doorway. The builder's defect liability period is 12 months. The homeowner is demanding full retiling of the bathroom and replacement of the adjoining bedroom carpet, which has a water stain.
1. Assess the builder's liability and outline the correct rectification scope.
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The builder is liable. Even though a licensed subcontractor performed the work and issued a certificate, the builder contracted with the homeowner and remains responsible for the completed work. The absence of pre-cover photographs and a flood test record weakens any argument that the work was done correctly, and the consultant's findings - membrane short of the waste and no doorway upturn - are consistent with the reported symptoms.
The rectification scope should not be limited to replacing tiles. The defective membrane must be made good: remove floor tiles and screed as needed, strip back to the substrate, and reapply the membrane with correct termination at the waste and an upturn at the doorway and wall junctions, then flood test and photograph before retiling. Replacing tiles over a defective membrane simply repeats the failure.
The adjoining carpet stain is consequential loss flowing from the defect and should be assessed on its merits. The builder should also check whether the work is covered by home warranty insurance, which may allow recovery against the insurer for the insolvent subcontractor's portion, and should notify the insurer promptly.
2. What quality records should the builder have kept, and how should the file be managed going forward?
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The file should have contained: the waterproofing subcontractor's licence details and scope; the membrane product data sheet and batch; dated photographs of surface preparation, membrane application, terminations at the waste, doorway upturn and penetrations; a flood test record with duration and result; and the certificate cross-referenced to the specific wet area. A certificate alone does not prove the membrane was installed correctly.
Going forward, the builder should introduce a hold point: no tiling until the supervisor signs off photographs and the flood test. The checklist should be property-specific, not generic, and stored with the job file rather than in a subcontractor's phone. Subcontractor records should include current licence, insurance and a deed or clause preserving the builder's rights if the entity later becomes insolvent.
For this job, the builder should reconstruct the file with the consultant's report, the rectification scope, photographs of the rework and a new flood test. Retaining these records also supports any warranty insurance claim and demonstrates a reasonable response if the dispute escalates.