Slab-on-grade is a common construction technique in areas with a high water table (so basements are not feasible). The house is basically built on top of a flat concrete slab with footings around the edge.
In new construction, threaded rods are cast into the concrete footings to secure the sill plates, but in older construction sometimes only a few nails are used and the house is essentially held in place by friction.
This instructable describes a process of retrofitting anchor bolts to the sill plates, with minimal disruption to the household
- Circular saw
- Claw Hammer
- Nail gun (optional)
- Nail Puller
- Hammer Drill
- Wood bits
- Wood Auger
- Concrete bits
- Levers or crowbar, blunt chisel
- Ear defenders
- Safety glasses
I used a consumer grade hammer drill. I tried several models and returned them to the store for various problems. On one, the motor brushes wore out after drilling a few holes. Another overheated. On a third, the electronic speed control failed; I suspect the vibration sheared off a component lead. It may have been better to rent or buy a professional grade tool. However, I don't consider that drilling a total of maybe 50 holes over a period of many weeks should overtax a consumer quality tool.
Notes on Masonry Bits
I used hammer grade twist drills with a spade-shaped carbide tip. After a period of use, the carbide tip wore down and became rounded over at the edge. I was able to refinish the edge using a diamond cutting wheel as a grinder.
It is possible that using a cutting lubricant such as flowing water would have extended the life, however I wished to use resin and did not want to saturate the concrete with water.
The bits become hot while working. It is important not to allow them to become too hot which will affect the temper of the steel. I cooled them occasionally by dipping them in a pot of water
- Expanding concrete bolts
- Threaded steel rod, washers, nuts
- Steel brackets
- Epoxy resin
- Tuck tape
For example, a code may specify 1/2" bolts every 4 feet extending 6" into the foundations, using either expanding anchors or chemical fastening (epoxy)