Concrete Blocks Crumbled on 8 x 17 porch: New Deck Over Top?
My 8 x 17 concrete back porch (2 ft. to 4 feet high) has about 4" concrete slab supported by concrete blocks. Gradually over the last 20 years several of the blocks under the top slab have crumbled all the way through.
I want to cost effectively fix the problem or rebuild. The slab has not collapsed yet but has a few hairline cracks. About 4 linear feet of concrete block has crumbled to nothing, just the top level of block by the steps, and in another area 2 linear feet of block, top level, by the taller steps, plus lots of hairline cracks tracing along the block seams on the side walls. The porch was built about the time of the addition, according to previous owner this would be around 29 years ago.
Here is the big question -- I want to permanently fix the problem, but don't want the expense of a complete new porch of this large size.
(1) Can this level of concrete damage be repaired? Temporarily or permanently? Relative cost versus doing a deck over it?
(2) Can I just build a deck over the top and ignore the deterioration of concrete without problems later when it falls apart? Note that the concrete slab is only about 6 inches below the slider of my family room, possibly not enough height room to install a joist for a deck anchored to the house. I don't think I should use the porch itself to support the deck over it because the main problem is the porch itself could collapse at some point in the next 3 to 5 years.
(3) Can I just demolish the concrete slab over the top of the porch and knock down the top layer of side concrete blocks, letting all the debris rest in the center of the hole. Then I can build a deck over and around the old sidewalls, using standard wood deck construction, and anchor the deck to the house?
(4) None of the above - any other suggestions?
There is not a water problem at the moment, but I have a cape cod house. It is possible the steep roof in conjunction with my gutter guards have allowed more water to roll over the top of the gutters and onto the porch over the years (solve one problem, create another). It is also possible that using salt on icy days in the winter on the porch also caused problems over the years.