Leaks in a multi-story building would naturally be more problematic than leaks in a home due to the sheer number of tenants inside. Waterproofing a multi-story building is also trickier, as it has more openings that water can seep through.

A Guide to Waterproofing Multi-Story Building

Allied Construction Services, one of the top providers of general construction services in the state, lists the most vulnerable parts of a multi-level building and suggests some tips on preventing leaks.

Flat Roofs

Flat roofs are more prone to leaks and moisture damage than other types of roofs mainly because of its lack of elevation, which causes puddles of rainwater to form. Over time, water might seep through the flat roof’s outer layer, causing leaks and damaging the layer underneath.


Contractors specializing in building maintenance services recommend you waterproof any area that’s exposed to the elements. All it takes for rainwater to enter the building is a small crack.

Tiny drops of water may seem harmless at first, but if they’re allowed to accumulate, they can corrode the steel bars within the concrete and cause what contractors call concrete cancer.


There’s always a risk pelting rain can cause gaps in your windows and let the rainwater in. Make sure to have a window from a reputable brand properly installed.

Considering the serious problems that can stem from moisture damage, namely mold and concrete cancer, it’d be more cost-effective to take precautions to prevent leaks.

Periodic Roof Inspection

While particular attention must be given to the roof, given that is the most vulnerable to moisture damage, you can’t discount other vulnerable parts, like the windows, balconies and walls. Concrete is a porous material, so even without visible leaks or cracks, moisture might still be seeping through the wall.

Right Waterproofing System

Leaks might also happen if your building’s waterproofing system isn’t suitable for the climate. The waterproofing system for a building in a hot climate, for example, would need to be resistant to UV rays while the one for a building near a beach would need to be able to withstand the harsh salt air.

A qualified building contractor, like Allied Construction Services, will be able to help you pick the right kind of waterproofing system. To set up an appointment with us, call (925) 297-5788 or fill out this form. We serve homeowners in Oakland, CA.