I want to do a monolithic pour for an addition the crawl space is 40" there will be an 8"deep by 24" wide footer and poured with a 4" slab this is all below frost there will be 6 courses of block on the footer and then addition on top. Is monolithic ok for this situation?Answer:
Yes, the description you provide is absolutely perfect for monolithic pour. Make sure to add rebars for your footers, at least 2#4 bars on each direction.
Also make sure to add dowls for your block, this will tie your block to the footings. The dowls are rebars with 90 degree bent leg of about 6 inches long. They are about 2 feet long total. The six inch leg is buried into footer and the remaining will be used to reinforce the block thus connecting the footers to the block.
I am assuming the block will form piers where the beam or column for the new addition will be rested. Since this element will be carrying the new addition, they will have to be grouted solid.
Another thing to remember is to add anchor bolts or Simpson's column base at top of blocks to receive the beam or column you're adding.
City and county building inspectors will be checking these stuff if applied in your situation. If no building inspector involved, it is a good idea to take photos while doing all these work. Someday the city may notice the change or if you sell the house, it always good to have these home improvement projects documented.
I ran into these proper documentation issue several times before and the best defense always comes back to documentation, particularly photos of before and after the pour. You can never go wrong with proper documenting what you’re doing.