Foundation support posts... adequate number ???

[BFA]

I am building a fairly small cottage... about 800 sq ft under heat... 1200 total under roof (porches, etc).  The plans called for a perimeter foundation and "brick" piers.  It is 30' X 36' with porches at front and part of back back i.e. a core area 24' deep and 30' wide.  The piers are about 10 feet apart.

My building location is on bedrock (granite) and therefore I have no need for a perimeter foundation but have poured footings on the bedrock to ensure a flat surface for the posts or piers.  The land is quite sloped towards the river and the posts at the back are from zero (i.e. rest on beadrock) to 24" in height.  The posts at the front are from 6' to 8' tall.... yeah, quite a slope.

While I have not changed the placement of the posts or piers, I have changed the materials.  The plan shows 8" X 16" brick piers.  I have used 6" X 6" pressure treated posts with 45 degree angle bracing of 4" X 4" pressure treated from the posts to the beams as well as having the laminated beams resting on the posts.

I have finished the ground floor platform and am about ready to start wall framing in the spring of 2007.  

What I cannot judge is whether the 6" X 6" posts and braces are adequate for support or whether I need to intersperse additional posts between the 10' centered posts ?  I know that more would be better but are they necessary or not i.e. what is the support strength of the 6" X 6" 's ?   Any advice would be appreciated.  Bruce

[optionguru]

How are your 6x6's attached to the concrete?  Did you drill into the granite and put in some rebar through the concrete?

Welcome to the site.

[PEG688]

What size are the beams ? The 6x6 is plenty big enough , the beam size is needed to know what the On Center ( OC)  spacing should be. If they are 4 x8 or larger you'll be fine, on a small cabin like that.

What size are the pier pads (concrete pads) ? Any rebar in then ? Site poured?  And as option dude asked how are the post attached to said concrete?

Up lift may not be a issue , but side to side / sliding / shifting might be . I generally drill in a short piece , or pour in a piece of rebar in the center then drill a hole up into the bottom of the post , so a pin effect ,post can't move / be knocked / slide sideways.

 Are your 4x4 's  bolted to the beam and post? Or just nailed?

Welcome aboard the board   G/L PEG    

[BFA]

All of the posts are placed in steel saddles that have about 8" of rebar encased in the footings.  As to the footing on the bedrock.  In all cases except two the footings are poured on v-grooves in the bedrock i.e. they cannot "slip" down the hill.  In two cases where this was not possible, holes were drilled into the bedrock and rebar was hammered into the holes with a sledge before being encased in concrete.  Also, no water or ice can build up on the uphill side of the footings thus, hopefully, avoiding them being displaced.  I am fairly confident that the footings are adequate.  It is really the number and size of the posts that concern me most...

[BFA]

The beams are two 2 X 10's, glued, overlapped, and nailed.  The riverside load bearing beam is 3 2 X 10's.

The pads vary in size but in general are about 18" X 18" and at least 8" deep.... some because of the slope of the rock are about 24" deep to allow the rebar on the saddle to be verticle.  I did not mention in the other reply to optiondude, the bottoms of the posts in the saddles are screwed and lagged to the saddles.  The tops of the posts at the beams are attached with galvanized ties or brackets by 3" screws.

By the way... thanks for the welcome's and I appreciate the quick responses....   Bruce

[glenn kangiser]

I had a similar question and one of our engineer members, Ryan B. posted some useful information -off the record as no one gets paid here for this stuff--

http://www.countryplans.com/cgi-bin/yabb2/YaBB.pl?num=1105331237/2#2

6x6 8' 24000 lbs