I added a 4 x 18 deck to an existing screened porch that's been attached to my house for many years. I used three 16x16x10 cement blocks in the corners and center on which the new double 2x6 sill plate now rides, then attached decking board "extensions" to the new deck and attached the "new deck" to the existing porch plate, making one larger area. The new roof section will be covered with polycarbonate rather then continuing the roof shingles that cover the porch.
The cement blocks are pounded into dirt, there's no gravel under them. My question is, I live in the northeast...should I expect the blocks to shift much in winter despite their weight?
Thanks very much, Ken