Phase 2 Construction Week 2: Concrete Preparation
We are here Phase 2 Construction Week 2: Concrete Preparation! This is a big week with a push to get ready for concrete. We are here to walk you through each step in this process on DIY concrete preparation.
There is so much you can do to prepare for your concrete slab to be poured! Trevor & I want to show you each step we have (well more Trevor since I am 36 weeks pregnant and bending over is rough for me now) he is doing most of the work at this point. I am just documenting it all :) .
How to prepare for DIY Concrete Slab
After removing the porch and laying out our addition, we began to prepare our concrete slab. Batter boards were put up to hold the string-lines used to square the building and paint the excavation lines. Once the building was square and painted out, we brought in an excavator and dug the footings as per the structural engineering plans. The footings are one foot by one foot below the slab, but vary in size by county and region. Once the footings were dug, the string-lines went back up on the same batter boards and form boards were put up, using the string-lines as a guide.
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After this, we prepared the under-slab. Locally, we are required to pour four inches of concrete over two inches of sand over a ten mil vapor barrier over four inches of crushed rock on grade, but again, these requirements vary regionally. After the under-slab is prepared, the ‘steel mat’ was tied. Again, local engineering and county code called for a two by two grid of #3 bars. (Pro tip: Rebar is sized by number, the number is how many eighths of an inch the rebar is i.e. #3 is 3/8’, #5 is 5/8”) Also, two #4 bars lengthwise in all of the footings. Two inch dobies are placed under the steel mat to hold the steel in the center of the four inch slab. Next, we have to dowel into the existing slab and epoxy #4 rebar into it to tie the slabs together. Using a roto-hammer and a ½” bit we drill holes 2’ on center and tie them to the steel mat with 2’ of overlap. The final step is to ‘hang the hardware’, or hold downs.
The engineering plan calls out the number and size of all hold downs required. Ours called for 5/8” anchor bolts spaced at 48” around the perimeter with 7” minimum embedment in the concrete. Also, there are four shear panels (required because of the very large window openings in each bedroom) which required eight specifically placed Simpson SDHD10 hold downs. After the hardware is hung, we are ready to pour our slab!
This is Week 2 of our Phase 2 Construction journey updates. Remember to watch the youtube video & subscribe to our channel. you will be notified when they next video is uploaded. The concrete pour is pushed off until next week since there was half a week we did not have power here in California was PG& E power shut offs. That is ok it gave us more time to prepare for next week! We are excited to pour our concrete slab and show you all how it turns out!