Expert: Bruce E. Johnson - 5/24/2010

Question
Hi Bruce,
  I have been demolishing my grandfather's house by hand.  My Parish(County) started giving us grief about the house even though it wasn't so bad. So knowing I had limited funds..and the slab would require money, I have been dismantling it.  I gave away most of the bricks which saved me haul off. I peeled off the roof rafters yesterday so I am just about down to the base frame of the house.  I have a project(the frame of a new pitched roof of my 4 plex) that I can probably use some of the wood for and I suspect I can sell the rest.  Once that is out of the way, I will be left with the slab to remove.  

I estimate that the slab is about 2200 Ft..and the real problem..its 18"-24" thick.  So I figure its at least 500k pounds on the low end.  I suspect that my best bet there will be hire a dump truck to do the haul off.  He can pick up so river sand for back fill on the return trip which should allow him to charge me a little less since he is making money coming and going.  I haven't nailed this down but I suspect thats the best way to go as it would take dozens of dumpsters.
 The real problem I am facing is..HOW do I break up that slab.. I know for most..you can use a bobcat with a breaker attachment and that will handle it...Or a back hoe possibly..but I am dubious as to what will actually work on a slab as thick as what I have.  My funds are severely limited and the parish has little patience.  I know an excavator will do the trick but that is 500/day 1500/week.
I was hoping I could possibly do it with a back hoe which runs about 250/day and 750/week. I am however dubious if this can handle the job.  I intend to get some bids from some people as with their greater skill they can do it quickly..and maybe for not much more than I can doing it myself..I like to have all my options..I doubt I can come up with much more than 2500 bucks to get it done with the backfill figured in..I am thinking i am screwed..the parish won't even let me leave the slab for any appreciable length of time..Sorry if this was a little bit of a ramble...but..I do that when I am trying to figure something out...
Any suggestions,guidance or advice would be appreciated.  Sorry if I sound like a dumb ass wanting the impossible..but when someone puts you between a rock and a concrete slab..what can you do?

Answer
Hi Daniel, that's a lot of concrete.  Are you sure that the slab is that thick?  Normally the slab will be only 4-6" thick except where the footings are located.  I think you will find that the majority of the slab is not that thick.  Anyway if you are going to do the work and someone is going to haul it away then the best one man tool would be a back-hoe with a jackhammer attachment.  The jackhammer is on the articulating arm side of the hoe.  You jackhammer out a bunch of slab in advance and then scoop it up with the bucket to put in the dump truck.  Keep jackhammering while the truck is making a round trip.  Whether or not that will be cheaper than just hiring a demolition contractor and having them remove the slab would depend on a lot of factors.  How close the dump site is for the concrete will determine how many trips the truck can make in one day.  A typical dump truck holds about 18 cubic yards.  If the slab is two feet thick you are looking at 4400 cubic feet of concrete or 162 cubic yards.  This will expand another 30% in size and kick that up to around 200 cubic yards of rubble that will need to be hauled.  Provided you can fill the truck to capacity each time you are looking at 12 or so trips to the dump site.  I would say that a single backhoe with attachments can demolish and load about 4 trucks a day.  Figure out all your rental costs and hauling costs and you will find that it is probably cheaper in the long run to have a demolition contractor bring in a track hoe and his own trucks and do the work in a day.   I hope this information helps, feel free to write again regarding this or other matter, sincerely bruce e johnson.