The preparation for the slabs was extensive and included ripping the entire front wall out from the house and supporting the roof with a temporary wall. Other construction work was done as well on another permit and of course I had to attend to my full time job as an electrical engineer.
But now we were ready for the pour. For the concrete, we choose fiber mesh 4000 psi type I/II concrete. The fibers that were put in the concrete meant that there was no need for the wire mesh that I had encountered in the demolition of the patio.
To deliver the concrete we found a company that mixes the concrete on site and then pumps it into the forms. The great thing about this method is that the charge is only for the concrete that you use. This is in contrast to the companies that bring the concrete premixed to your site. If there is any extra concrete and there always is if you want to be on the safe side you are charged for it.
It does cost extra to get the concrete pumped, but we felt we needed the extra time to finish off the concrete because my experience with finishing concrete was watching youtube videos, dad hadn't finished a slab in about 30 years and we had both read that finishing concrete with fibers was more challenging.
Luckily dad had kept his concrete tools and we had at our disposal a magnesium bull float, fresno and smaller hand trowels. We made some small plywood boards to use for standing and kneeling on the cement for finishing as well. With everything ready we ordered the concrete.
On Saturday the truck arrived and it was go time. It took about 30 minutes for the pump guy to fill the garage forms with about 10 yards. Not only did he pump the cement in, he smoked a cigarette and screeded the cement at the same time. As I dabbled with the hand trowels, Dad worked his magic and finished off the cement. Finally, I put caution tape around the slab to prevent anyone from walking on it.
The cement guys mentioned they knew some block guys that could give us an estimate for doing the walls. We were interested in speeding up the project so we asked that they stop by.
It had only been an hour since dad had put the finishing touches on the concrete, when the block guys showed up. As we were talking and the block guys were coming up with an estimate, one of the block guys decided he had to get a closer look at something and ducked under the caution tape and stepped onto the slab. I immediately panicked and yelled, "Get off the slab! Its fresh!" The guy stepped off and I looked down at the green concrete where he had stepped to asses the damage.
I was completely amazed. Not believing my eyes I looked again where he had stepped. The concrete surface looked as if he had never stepped on it. The block guy said "oh it was poured today. I see why you were concerned"
The block guy jumped back on the concrete and walked over to what he wanted to look at. With each step he took I looked to see if there was an imprint. Absolutely nothing!
After they left, dad and I sat in a couple of lawn chairs and watched Green concrete bake in the Florida heat.
The next weekend the cedar porch slab was poured and finished which is shown below. Note the small lizard basking in the sun.
After the pour we kept the pads wet because it turns out that the finished concrete will be stronger if it is kept wet for 30 days. (Search on GRAPH: STRENGTH OF CONCRETE AFTER DAYS OF MOIST-CURING in this Link)
If a contractor had done this it would have obviously been faster. But would it have been cheaper? Based on contractor estimates for doing demolition and building two concrete slabs using http://homewyse.com/ I get the following results.
Service Contractor Owner Builder
Demolition / Excavation 153 hours $6885 $1830
Build 735 Sq Ft Slab (20 Yards Concrete ) $5100 $5966
Grand Total $11985 $7796
From the above results it is apparent the I saved a bundle from doing the demolition work. However, the contractor appears to be cheaper for the actual concrete work. Based on the contents of this blog you probably have guessed why this is. Does piano ring a bell? haha Also, perhaps the contractor knows how to get his materials cheaper and use them more efficiently. For demolition it is mostly labor cost and their is little material cost involved so that is where I saved.
Despite being a green builder dad and I ended up having successfully built two concrete slabs without having caused the house to fall down after pulling the front wall out or having to break out the jack hammer and to fix a serious mistake.
A whopping $4189 or 35% was saved. Cue the cash register sound.
Happy Building!
The Dr
Love the detail and photos and cost breakdown. Very nice.
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