How should membrane waterproofing be estimated?

Estimating membrane waterproofing by square footage of walls and floors is the most logical approach because the material is applied over surface areas that need protection from water intrusion. This method takes into account the total area that will be covered by the waterproofing material. Measuring in square footage allows estimators to accurately determine the amount of membrane required for coverage, factoring in the dimensions and layout of the surfaces.

This method also provides a consistent basis for calculating material costs, as membranes are typically sold in square footage units. Additionally, it allows for more accurate evaluations of labor costs, as the time needed for installation can vary based on the total area being worked on.

While other options like measuring by linear feet or counting the number of rolls can be helpful for certain specific installations, they do not provide as comprehensive a measure for estimating the total volume of waterproofing required when dealing with flat surfaces like walls and floors. Focusing solely on labor cost overlooks the necessity of understanding material requirements, which is critical for an accurate estimate.