I'm reorganising and adding to my kitchen floor cabinets. The "off the shelf" plinth height these days seems to be 150mm. However, my old units have legs that will only go down to 160mm. I'm replacing these legs with new B&Q ones so will have the same 150mm legs on all the units. When I set the hieght of the units fro the floor, should a leave exactly a 150mm gap or should I allow a few mm spare?