Bricks, Masonry, Asphalt and Concrete - How to pour slab higher than allowable fill height?

I put an addition on and wanted to extend the concrete covered porch. I have an 8 inch poured foundation with max unbalanced fill of 7 ft. that would place the max fill outside at about 3 "bricks" below the bottom of siding--the concrete is made to look like brick. But as the photo shows, the top of existing slab is way above that and in fact is about 5inches above the top of foundation. I am not sure what they did in the past as my house is 108 years old and I don't know when porch added. I had heard that the 7 ft backfill applies to dirt and that I could put 7 ft of dirt and then put gravel and the slab. I talked to the inspector when he was here and he wasn't quite sure but seemed OK with that. He asked about flashing and I said I would flash over the bottom course of siding. Since the bottom of slab may be above the seal plate, I think I would make slab thicker at foundation so that I have concrete to concrete-prevent any termites from getting in through a seal plate exposed to gravel.

sorry photo may not be clear--the bottom of siding is visible just above the black pipe. the starter strip is placed on the seal plate for a reference. If this should be posted somewhere else, such as decks section, please let me know. thanks

http://i42.photobucket.com/albums/e311/hammerash/c430963e.jpg

I think you would want to pour a monolithic slab, or turn-down slab. Let the fill be higher in the middle but allow the concrete to be thicker where it meets the existing concrete. I would also think you would want to remove the siding and flash over the sill plate with a membrane product then flash over the new concrete before the siding begins. I would also contact a good finisher and run it by him.

by "thicker where it meets existing concrete", do you mean the existing foundation for the addition-seen in the photo right below siding? that is what I meant when I said make it thicker so that you have concrete to concrete.

yes I meant that I would remove the bottom course of siding. I should call siding guy to see how to handle this cause If I remove the entire bottom course then the second course becomes the first but doesn't have a starter strip and is not really attached. Maybe you could cut first course just above slab level and then unhook bottom of second course from it. Remove the shortened first course shove flashing up under the second course and then renail the top of first course and rehook the second course. all the holes would be above slab height.

what membrane product are you thinking about? I would like to do so research on it

"flash over new concrete before siding begins"? is what I described above what you mean? do you thinkthe flashing should extend down into the fill? if you do that then you don't have concrete barrier to prevent termites. I would think that there would always be space between that existing poured foundation for the addtion and the flashing. maybe the membrane you mentioned would take care of this concern.

thanks

I don't think you need to flash into the fill, just past the sill plate so you don't have fresh concrete touching the plate. It seems as tho you are wanting to use the existing wall as your form. Protect that wall with a membrane like ice & rain or other peel and stick products. Yor might even use a brush-on product where the sillplate is attached. And I would not just stick some flashing up under the siding. I would take off 16"-18" and secure the membrane to the wall, pour the slab then put a bead of elastomeric caulk at your seam of new concrete and membrane, your flashing about 12"-16" up the wall with a drip edge that is 3/4' above the new concrete and my starter 1/2" above that. That may seem like overkill, but it's your house....

An important fact that I didn't mention is that this is going to be covered. The edge of slab away from house will have footer to support the posts that will be located there. Sorry, I guess I should have mentioned this before. Would this change the suggestion for how to flash? you said to put caulk at membrane slab joint but if I flash down past the seal plate, the membrane would not be visible. the flashing would be over top of it? I thought the flashing would go down between foundation and new slab since I am not really worried about rain water coming between this area-more concerned with moisture wicking from below and termites. so I hadn't planned on drip edge. maybe put two layers of flashing, one down between sealplate/foundation and new slab and then over top of that one that has drip edge-since not sure when roof will get put on maybe best to have a drip edge as you suggest. maybe overkill, but not that much extra work really. So something like weatherwatch (from GAF-roofing paper that is used at eaves and rakes-also known in my parts as ice dam) is what you would suggest for the membrane? I may have some of that leftover somewhere. what are some of the spray on membrane names?

You're right.........The fact that it will be covered makes it seem a little overkill. The point of the elastomeric caulk at the membrane and new concrete is for pests and moisture. It will also be helpful when you wash off the porch and water has a chance to go where it shouldn't. How are you going to transition the roof next to the siding when that time comes. You will probably want to flash at that intersection as well. You might as well take all the siding off the area, tie in your porch cover, flash everything, then side your area fresh............

I'm still confused on what you are suggesting. I understand the membrane. How low would you flash? You said to seal plate but it seems to me that if you do that then the membrane would not be visible after slab poured. Then you mention to put caulk between concrete and membrane?? Wouldn't you be more concerned about pests coming from below the slab at seal plate- essentially undetectable. the only thing.

Oh, you mentioned monolithic slab. That is what guy that I got bid from said on his message today. I didn't get a chance to speak with him. What exactly does that mean? by your first email, I didn't know if it was same as turn down slab and both mean to have higher fill in middle so slab thicker at edge. He said he would pour the footer away from house first and then pour the slab next day.

yes I would flash at top of roof. I actually just had the siding put on. It's a long story but I had contractor go bankrupt then got new one but couldn't afford to pay him to do whole job. I am now taking over. So the siding got done as part of my contract. I have to look to see what best way to handle siding would be. The covered porch will continue around side of house also, but will be trex deck (not concrete. I don't really want to remove all that siding. Was hoping to just remove where my ledgers have to go (3 of them-one at top of roof, one at porch ceiling and one at deck surface) and flash where needed.