Bricks, Masonry, Asphalt and Concrete - Concrete sonotubes on bedrock (cottage)

I am building a 1 story cottage 2 hours North of Toronto. The entire site consists of bedrock under the soil, ranging from 6" to 2' or 3' of soil. I will be speaking with my local BI, but just wondering if anyone out there has done this (or knows what to do)? here was my plan. Dig until I hit the bedrock wherever I plan a peir, then insert 10" dia. sonotubes directly onto the bedrock with one 1/2 peice of rebar right down the middle (not touching the bottom) and to within 2" or 3" of the finished grade of the peirs, which will be as high as 4' in the lower lying area's. I need this space to accomodate a remote composting unit, and to just have space underneath for general repairs. the cottage will be 790 sq/ft, the whole cottage will 12' wide and 66' ft long (facing the lake ofcourse) 32' ft straight front wall (front measurement) and then both sides will angle 45 D inwards another 12' (again front measurement), so the longest joist span will be 12'
Does this sound O.K.?
should I be drilling into the bedrock and inserting rebar to tie in the concrete?
should I be using more rebar, larger tubes?
how far apart should the tubes be 6', 8' ,10'?
I mentioned the rebar not touching the bottom, the reason I mention this is because I have read this, why is this?
I thank all, who may respond! EH!

Without knowing the type of bedrock, your seismic zone, and other concerns, it is not within the scope of this board to answer your questions.

A few concerns regarding your plan come to mind, however.

One, is that considering the shallow depth of some of your posts, pinning the pillars to the existing bedrock is almost a surety.

Second, the height of pillars and the number of reinforcements is directly related to their height and diameter, and overall building loads...and these issues can only be adequately addressed by your local building code administrators and structural engineers.

It is desirous to keep rebar encased completely within concrete to retard rusting which will cause rebar to swell and eventually crack the concrete.

Thanks for your reply, I will definately have the plans stamped by a architect or enginer (code may dictate, and to be safe!!). Basically when I said 6" of soil at some places, I meant then you would hit solid rock thats been there for thousands of years or more, well in that situation couldn't I pour it and pin it. the downward pressure on solid "Canadian Shield" shouid be fine (i will have to make sure ofcourse), and as far as lateral movement goes, once the laminated beams, joists, walls, and rafters (not to mention plywood) are completed, I can't see it going anywhere. I mean, I have never heard of someone having to boar through rock to pour concrete, sounds a little foolish - no?
Maybe we got our wires crossed, let me know what you think
thanks

Nope.
No wires crossed.
Simply because you hit 'bedrock' does not mean that your 'bedrock' is an acceptable rock upon which to build or pin a structure.

Each kind of rock or mineral has its own weight bearing characteristics, compressive strengths, shear and sliding characteristics and there is no one magic method for dealing with them all.

Couple that with the requirements of your seismic zone, and you are just playing a kind of novice builder's 'spin the tail on the donkey' where you get blindfolded, spun around, completely disoriented and hope to get the tail 'spot on'.

Technically, a 'bedrock' of gypsum will have the same criteria as having been there for millions of years as perhaps granite 'bedrock', but that does not mean that gypsum is an acceptable base upon which to build a home anymore than might be oil shale or slate or other types of 'bedrock'.

If you are REALLY interested in the vast variances in the geology of the even vaster region called the 'Canadian Shield' read on:
http://www.thecanadianencyclopedia.com/index.cfm?PgNm=TCE&TCE_Version=A&SectionId=638906&mState=1

You may find given your soil and seismic conditions the only way to construct an approved structurally sound building is to set piles down several strata before hitting a layer of 'bedrock' that can bear the load of your house.

It is NEVER as simple as just pinning to the existing exposed rock, and it is apparant that you don't understand all the structural, seismic, load, soil and even rock bearing elements involved and I mean no offense by saying so.

Better to hire a professional because you are in over WAY your head at this point. :eek:

I appreciate your post, thank you. But up in these neck of the woods most of the cottages are just built on concrete blocks, right on top of the rock. (by the way, I am pretty sure the rock is granite). I just thought it would look more finished. Assuming that the rock is able to withstand bearing the load of a cottage, would you recommend just using blocks instead?
Thanks for your help!