I am designing a small home, in such I will using some below grade space as living space. I have decided to go with large (4'x4') windows 18" from ceiling (or below I-Joist). So I need to be at least 6' down. These will be used for needed natural light, egress, and fresh air.

At my local lumbar yard I have found a system called Well-Craft (I believe). They are 18" high 4 foot wide half circles made of plastic with molded in stairs. I cannot seem to find other competitors of this product, much less other ideas besides pouring concrete or using landscape retainers.

Anyone have any ideas or other manufaturers' names? I wish I was made of money, but I am not. I also will be building my home by myself... so though labor is cheap, if I could save time so I could work on other projects that would be great too!