How to split the surface with rectangle?

I want to split the surface with rectangle!
The surface is flat! I know the length and width of the rectangle!
The distance of each rectangle is 7mm!
After dividing the surface ,the rectangle has a gird every 3.5-4m!
The gird width is 20mm!
The final result looks like this picture!

I uploaded my DWG file and GH battery! Can anyone help me! Thanks!
split (12.7 KB)
roof.dwg (52.5 KB)