At EPRO, our main focus is commercial waterproofing and vapor intrusion solutions. However, sometimes we come across residential projects with interesting "water woes."

The following example has become a far-too-frequent occurrence in Canada, and was brought to our attention by one of our contractors. In this case, the right, properly installed waterproofing system could have saved a homeowner a great deal of time, money, and potential headaches.

Costly oversight at a Canadian Residence

During a multi-million dollar redevelopment of a historical property, a builder neglected to investigate the geotechnical conditions of the land and found that a proposed cost-saving measure was more expensive than they had bargained for.

A residential home builder chose to follow the minimum building code but neglected to consider the need for waterproofing and this has resulted in a loss to the homeowner exceeding $500,000.

While initial plans called for basic damp proofing and perimeter drainage, site inspections revealed minimal drainage and only a single layer of dimple board for drainage on the exterior. This cost-saving approach to building envelope protection left the homeowner high, but not dry, and with limited recourse against the water ingress.

(Typical OBC Residential Damproofing)

Was this situation inevitable?

There is a significant misunderstanding in Ontario between damproofing and waterproofing and unfortunately basic residential damproofing required by code does not address this situation nor is there any specific requirement on builders to investigate and confirm suitable geotechnical conditions.

According to our contractor a basic well drained waterproofing system could have been incorporated during construction for about $15,000 and a more comprehensive watertight solution for about $50,000.

This scenario underscores a common industry practice where builders try to minimize costs by discounting the importance of envelope protection. In this practice, builders will assume a “one-size-fits-all” approach and refer back to the Ontario code. Unfortunately, unless insisted upon by the homeowner, the builder will often do very little extra in these situations beyond installing sump systems which can be easily overloaded during heavy rain events. Additionally, due to climate change, many areas of Southern Ontario are seeing more frequent heavy storms and persistent precipitation. Buyers are often unaware of potential risks and regulatory authorities are slow to adapt.


This case serves as a reminder of the importance of thorough due diligence and proactive measures to mitigate risks due to surface and groundwater intrusion into residential construction projects. The issuance of a permit alone is no guarantee of quality, and most local authorities don’t even inspect for waterproofing, leaving this to the builder’s risk.

At EPRO, our staff of professionals regularly provide options to resolve potential issues related to both waterproofing and site environmental concerns. We collaborate and communicate with owners, engineers, architects and builders, and our advice is provided free of charge. Email or call us today, we're looking forward to working with you!