ᐅ Light Wells and Basement Windows: Practical Dimensions, Materials, and Considerations

Hello,

we are building a small partial basement with a waterproof membrane ("black tank") as follows:

We will take care of the basement windows and light wells ourselves. Currently, I am researching what would be practical in our case regarding dimensions, material type, and finally specific products and manufacturers. Below is a brief summary of some basic conditions:

• Basement within the thermal envelope of a KfW55 energy-efficient house
• 12 cm (5 inches) insulation
• cast in place concrete
• waterproof membrane ("black tank")
• purely utility basement with
• Basement 1: workshop and storage
• Basement 2: utility room with equipment for air-to-water heat pump, photovoltaic system, electrical
• Basement 3: storage for food supplies
• no drainage inside the basement, so no connections for washing machine, sink, etc.
• The soil report indicates an infiltration rate of 10E-3 to 10E-4 m/s, so water drains well through the gravelly/sandy soil
• The backflow prevention level is above the window sill
• The pictures show an extension to an existing semi-detached house
• to the upper left a wall extends away, and directly to the left of the house there is a bicycle shed, so Basement 1 receives limited natural light

What is important to us:

• good ventilation option (a workbench will be installed in Basement 1, so good ventilation is necessary depending on the type of work)
• a reasonable amount of daylight, although it is clear that electric lighting will probably always be needed
• burglar resistance
• possibly an emergency exit option. I am not sure if this is necessary, but I thought it might be useful if someone is working in the basement and unaware in case of, for example, a fire affecting the upper floors and stairwell/hallway…
• installation should be possible for me as a layperson (with the help of instructions and support from more experienced people, etc.) and not too complicated
• affordable but not cheap

What I currently think:

• Due to KfW55 requirements, we need
• triple-glazed windows
• appropriate insulation boards for the light well
• fiberglass reinforced plastic (FRP) light well is easier to install
• because of the backflow prevention level, the light well probably needs to be connected watertight
• drainage of the light well should be sufficient by percolation into the gravel beneath given our soil conditions
• possibly a combined package of matching window, light well, insulation, and installation kit?
• window and light well size, not sure what is sensible here...
• So far, I have looked at manufacturers like ACO and MEA but I am still unsure what would be appropriate due to lack of knowledge…

I am grateful for any tips or advice regarding the points mentioned!