ᐅ Basement window wet / water is leaking in underneath the window sill

Hello everyone,

We are currently still in the construction phase and have occasionally noticed that water has entered below the window sill of two basement windows. In some cases, there was so much water that it ran down the wall to the floor, or at least it was visibly wet directly beneath the window sill. The window well and windows are not designed to be watertight against pressure water.

We have not been able to identify the exact cause yet, but we suspect that water collects in the light well during rain, cannot drain away quickly enough, and therefore flows into the basement room at the window level. It is possible that water also enters the light well from the side...

We have addressed this issue with the construction supervisor several times, and he only said it would be resolved before handover. As a first step, the drainage of the light well was cleaned because it was apparently clogged with construction debris. Additionally, a glass pane will now be installed over the light wells to keep rainwater out from above. The groundwater stands about 30cm (12 inches) high near the basement.

The question is, of course, whether this is an appropriate solution or just treating the symptom? To simulate the situation, we plan to pour 1–2 buckets of water into the light well to see how quickly or slowly it drains away...

How much water should the light well be able to drain and within what time frame? Is the idea of installing a glass pane a proper solution?

Would it make sense to install a backflow valve in the light well, which would also filter debris?

Pictures 1 and 2 show the water flow quite well, picture 3 shows the well from the outside.

Thanks in advance for your feedback!

If you have groundwater standing against the basement, why wasn’t a waterproof design for the window wells chosen? That seems like a defect to me. The window wells can also be connected directly to the sewer system, which might be a solution. But of course, only with a backflow and odor trap.

Marvinius II schrieb:
If you have groundwater against the basement, why wasn’t a waterproof installation for the light wells chosen? That seems like a defect to me.

Hello,

the contractor decided not to use this because of the low groundwater level; hopefully it’s not a mistake that we didn’t insist on it. The window itself is installed at about 160 cm (63 inches) above the basement floor. The groundwater level is around 30 cm (12 inches), roughly up to the floor slab. The question is, what is the maximum level during heavy rain?

What is the distance from the bottom edge of the light well to the window in centimeters? It looks like 10–15cm (4–6 inches)?

Also, please clean the drainage of the light well.

tomtom79 schrieb:
What is the distance from the bottom edge of the light well to the window? It looks like 10–15cm (4–6 inches)?

Also, please clean the drain of the light well.

The drain has been cleaned; the photo is from before. Since then, at least, we haven’t noticed any visible wet spots inside below the window!

The distance is about 10cm (4 inches), which should be sufficient?

The construction should include drainage and gravel beneath the light well to allow water to drain away.

I would position the shaft 30-40cm (12-16 inches) deeper.