ᐅ Installation of window wells for concrete basements, basement insulation, bituminous waterproofing membrane

Hello.

I am currently trying to figure out the best way to install light wells in the basement, or rather, how it is usually done.

We are handling the waterproofing (against ground moisture / non-stagnant seepage water in combination with drainage) and basement insulation ourselves.

Right now, I have two different recommendations:

1. The manufacturer of the liquid waterproofing membrane (LWM) says:

- Mark the positions for the light wells and drill holes
- Apply primer up to the light well area
- Apply two layers of single-component LWM with reinforcing fleece up to the light well
- Set and screw the light well into the still-fresh LWM
- Apply waterproofing again around the light well using LWM
- Extend 100mm (4 inches) perimeter insulation up to the light well
- Coat the inside of the light well with sealing slurry

2. Acquaintances told me (and this sounds "better"):

- Mark the positions for the light wells and drill holes
- Apply primer completely
- Apply two layers of single-component LWM with reinforcing fleece completely
- Install 100mm (4 inches) perimeter insulation completely
- Only then screw the light well onto the insulation (using the appropriate mounting set)

What would you recommend? Have we missed anything fundamental?

Is there perhaps some kind of "manual" similar to the "Bautenschutzguide" from WeberTec?

I still prefer option 2.
Or is there any reason against it?

Unfortunately, I can’t answer your question as I am also an amateur, but I have a question regarding the installation of a light well.

In our case, it was screwed onto the insulation, but we have now heard that it would be better to screw the light well directly onto the concrete wall and then finish the insulation at the light well?

This week, we received our basement, and I talked with the basement contractors.
Nowadays, they always focus on the insulation.

Please do not screw the light wells onto the 100mm (4 inch) insulation. Usually, the outer edge of the basement tank (if there is one) and the outer edge of the cladding or external thermal insulation composite system (ETICS) are aligned, resulting in about a 10 cm (4 inch) wide gap between the light well grate and the house edge. This looks odd and does not make sense.

We have always used option 1, but omitted the waterproof slurry. This is unnecessary if I have already insulated up to the window with either single-component or two-component insulation. I consider it much more important to apply a silicone fillet along the inside edge of the box on uneven tanks to protect it from water and dirt.

Personally, I have concerns that fastening the light well through 100mm (4 inch) insulation may allow too much movement due to weight load, potentially causing damage to the mounting sets, the tank, and/or the insulation.

I hope I was able to provide some helpful insights!

In this case, the spacing is correct if the shaft is installed flush with the top edge of the basement floor. Since we are building with a timber frame, we have to position it about 30 cm (12 inches) below ground level anyway. Therefore, the gap would not occur.