Hello,
I am going to make a foundation for a greenhouse and plan to screw and glue beams with 45X145 NTR/A.
The frame should be 306 X 406 cm and I am thinking of 7 beams that are crisscrossed/overlapped at the corners.
Is it sufficient to place this on 6 cement blocks or will it sag?
Is it better to place it in a "trench" with some crushed stone at the bottom?
I assume the construction will be heavy enough so that the greenhouse made of channel plastic/aluminum won't blow away..
