Plants growing through foundations

I clearcut an area to build my base, part on land, part over water. No matter how many time I chop down the grass and clover, they regrow, blocking my front door and my ability to walk around my base. I've tried using pebblet foundations, bouyant foundations, and grass floors, but no matter what I place down, all the plants regrow. The clover is especially bad, as it regrows VERY fast. Nothing I do stops it from coming back.