Our home exits through double doors onto a concrete deck beneath the deck above. The concrete slab is about 21' wide by 9' deep. The pad has settled so it pulls away from the side of the house about 3/4" and has sunk about 2" at the side 9' from the house. There are cracks in the slab radiating from the concrete pillars which support the posts for the upper deck (where we can see the slab has sunk at least 2"). At the house the concrete is about an inch below the vinyl siding and the doors sill sits about 2 1/2" above the concrete. We have a water tap at the (weather protected) corner of this wall.
We would like to build a plank deck with either vinyl planking, cedar, or treated lumber to replace this concrete, extending the deck 4' or 5' into the yard.. I need to know if I should remove the concrete and tamp in a gravel base beneath the deck, or can I build the deck directly over the existing slab. Would it be wise to pour a new concrete slab beneath the deck. Can the deck surface be above the bottom of the vinyl siding? Could/should a gap be left between the decking and the wall? How would I attach the deck to concrete if the slab is left in place?
Hi Barrie, I can't think of any way to attach decking to an existing pad when you only have 2 1/2" of clearance under the door. You definitely don't want any wood (even pressure treated) to be in contact with the concrete.
It sounds like the base for the pad was not properly prepared and / or compacted. That is why it is sinking and pulling away from the house. If it is cracking around the support posts for the upper deck, there are probably proper footings in place for the posts and the pad is collapsing around them.
The best bet may be to take out the concrete (carefully around the columns!) and start whatever you want from scratch. If you go with a wood deck, you will be able to keep it up off the ground and allow air circulation - very important to let the wood dry out to stop rotting.
If you are serious about this, you should put your requirements in the "post your projects" section so you can get some local contractors to come and have a look and offer suggestions.
Good Luck with it!
Kettleby Handyman Services
I agree with Jim.
I think if you leave the concrete in place you will have more problems to deal with then if you removed it and started new. We all know of someone who covered something up because they thought it would be easier.
When you do decide to make a change starting with a nice clean area is always easier!
Search the TrustedPros directory and discover the best contractors in your area.Find your home service pro