Replies

1. 
   frenchy | Sep 24, 2008 05:25pm | #1

   woodandiron.

     first if the slab is built properly it won't break during an earth quake.. Any earth quake severe enough and close enough  to destroy a  properly wire reinforced concrete slab will also do enough damage to the rest of the house to require replacement anyway!

    Don't forget in addition to the wire mesh holding everything together you can get those fiberglass threads in the mix.

     Second even if cracked there is a probablity the plastic tubing won't rupture..

     The "plastic" tubing is made of crossed linked poly and extremely tough and durable.

     If only once crack does spring a leak it's relatively simple to air hammer the concrete away and make a repair followed by patching of the concrete..

      Don't forget you normally have to put a mat of sand down followed by 2 inches of foam  those will isolate the pad from damage which might occur otherwise.  Then the tubing is attached to the wire mesh  so we're not talking about a sidewalk here..

   
   

   ---

   Edited 9/24/2008 10:28 am ET by frenchy

2. 
   shelternerd | Sep 24, 2008 06:49pm | #2

   I've broken into and patched tubing damaged in slabs a couple of times, it's not that big a deal actually we just snip and sleeve the break with dishwasher tubing and band clamp it on the exterior and replace the concrete. you can get away with a pretty surgical incision. We also back up our 6x6 slab mesh with #3 rebar 30" OC each way which is cheap insurance and helps keep the mesh flat and in the middle of the pour.

   ------------------

   "You cannot work hard enough to make up for a sloppy estimate."

3. 
   sungod | Sep 24, 2008 07:10pm | #3

   Frenchy is mostly right. The slab should not crack. When slabs do crack, it does crack by how it is poured. Look at a slab that is cracked down the middle, they poured one side, then waited for the next truckload. The two different sides are curing as two separate sections.
   On the subject of earthquake damage. Your house is subjected to more damage if the ground is more "looser" filled ground. The San Fernando Valley, SF Bay areas, Mexico City and parts of Japan/Taiwan have a lot of loose ground. When a big bus or truck goes past your house and it rattles the dishes, your on loose ground.