ᐅ New Construction with Basement | Waterproof Concrete plus Perimeter Drainage

Hello knowledgeable people,

We are planning to build a new house with a basement. According to the soil survey, the ground up to a depth of about 5 meters (16 feet) consists of impermeable glacial till. Below that is permeable sand. There is no problem with rising groundwater here. However, due to the soil, surface water can be directed towards the basement wall.

The expert says the basement could be constructed either with masonry and drainage boards on the walls or with waterproof concrete. For masonry, a perimeter drain with a sump pit should be considered. If waterproof concrete is used, the expert states that no drainage is necessary.

The construction company recommends a masonry basement with waterproofing against hydrostatic pressure and perimeter insulation boards. Additionally, a perimeter drain and a sump pit should be installed. Alternatively, they suggest using waterproof concrete with open water management. However, they generally still recommend a perimeter drain with a sump pit for waterproof concrete to avoid long-term problems.

These measures/recommendations would increase the cost of a masonry basement by about €17,000 and for waterproof concrete by €7,000 with open water management or €16,000 with perimeter drainage and sump pit.

Basically, we would lean towards using waterproof concrete, but the recommendation to still install drainage seems a bit like a double safety net to us. The construction company justifies this because of the hydrostatic pressure and the expected higher humidity in the basement due to capillary action.

Since we are building the house with a central ventilation system, connecting the basement rooms to it would be straightforward.

We now have to decide what to do and are a bit unsure. What is your opinion? Does anyone have experience with waterproof concrete and glacial till soil? Is moisture an issue here?

Thank you very much for your input.