Hammer drills

[EWAYota]

The foundation is most likely not pre stressed concrete. As already mentioned it requires a lot of work at the time of pouring and is really expensive, you also don't have problems with tension in house foundations. I believe most prestressed pieces are also pre cast pieces, like the new Bay Bridge. Most of that deck and bent caps are pre-cast and pre-stressed (not in that order) in Stockton. They're floated out there on a barge and installed. Now you could still run into rebar or welded wire mesh in your foundation. I don't think this will be a problem for the drill but you'll know when you hit it. I don't think it'll cause a problem with future cracking (although I am not an expert and it's been a while since I took my concrete design and pre-stressed classes).

Mike

I was just going to say that, well not quite but close. Pre-stressed concrete are pre-cast pieces, ie: bridge girders. Strands of cable are ran from one end of the form to another then stressed to a tension strength. Rebar and foam blocks can also be included, for strength and weight issue (foam).

You could encounter rebar or mesh, as that is used not only to help with shape but with strength as well. I don't see that being much of a problem for what you will be doing.

[BruceTS]

One other way the pre-stress foundations is by using cables, I've seen this done in a few areas, where steel cables are placed in the forms criss crossing the entire foundation, then tensioned before the pour begins....

[Vermejo]

Cordless drills with the hammer drill function when used heavily seem to fail at the clutch with time. These drills are made multifunctional for convince as being able to drill masonry occasionally while carrying lighter functions for the most part. I've killed a few drills on the hammer function including DeWalt and Milwaukee.

I got this Bulldog Extreme from Bosch last week, replacing a lower model. Bit capacity 1" solid bit, 2-5/8" thin wall core bit.



The size of hole to be drilled will relate to the size of hammer drill needed. Note: many masonry bits don't require hammer impact, just consistent water cooling.