We recently poured a safe room as a monolithic ICF wall/insulated concrete deck. The room was about 10' x 12'. Walls were poured at a typical 6" slump, then additional water added to mix for the deck (this was planned so redi-mix ensured strength was sufficient after water was added). Mistake we made was adding the water after the walls were filled - we didn't account for the +/- half yard of concrete in the pump. The first 1/4 of the slab were poured with a mix that was drier than ideal, although it all turned out great. Horizontal 2x4's were fastened about 1/2" above the top of the ICF and leveled, then 2x4 bracing was placed vertically below this horizontal 2x4 and down to the slab. Interior of the slab was supporting with adjustable bracing. FYI, the extra slump was needed, since we were not able to access the top of the slab for finishing and walls could only be externally vibrated. The safe room was poured inside the basement of a previously built home. Space from top of finished concrete deck to bottom of floor joists was about 14" and we could only access this during construction/concrete placement from 2 sides (other 2 sides were tied into existing basement walls). |