Expert: Bruce E. Johnson - 6/21/2009

Question
my garden is about 20ft x16ft and is all lawn can i put decking straight on top if so how far do the spars need to be apart or can i lay flag stones to support the frame

Answer
Hi steven, I don't know what is available in your area but here in the States we can get precast footing blocks made specifically for supporting decks.  They are 16"x16" with a socket cast into them for inserting 4x4 posts.  But yes you can use a flag stone if it is thick enough, at least 4" and at least 12'x12".  Or you can dig a square hole six inches deep and at least 12"x 12" and pour a concrete base block in place using bagged concrete mix. I would spray the area with a grass and weed killer and then cover with a black plastic prior to building the deck.  This will keep the grass from growing back up through, but clear the spot where your pads are going down to dirt for a good foundation.  I hope this information helps feel free to write again regarding this or other matters, sincerely bruce e johnson..bejohnsonconsulting.com