The replies that I have seen assume that the posts are for a railing; actually the original question was about 6X6 posts supporting a deck about 12' high above a concrete patio.
Editor's Comments
Bot the 4x4 and 6x6 post anchor have been tested in the lab for compression loading on 2500 psi concrete. The 6x6 on a three sample test had numbers around 25,000 lbs before the first sign of deflection was observed. The wood post blew up around 118,000 lbs and the other two samples the instrument shut down at 120,000 lbs.
So compression loads are a known quantity. However you should apply preservative on the end of the post before installing the anchor.
This is because the elevation of the base is 5/8" and less than 1".
Aug 02, 2009 Rating
Attaching Titan Anchor to Concrete by: Editor - Rich Bergman
When attaching the Titan anchor to concrete the typical concrete fasteners we recommend and sell - but are not the only kind you could use - are the GRK Caliburn Pan Head concrete screws.
These screws have a 1/4" shank diameter and are 2-1/4" long. In fully cured concrete these screws are rated to have over 2100 lbs of pull out strength. So if you use all eight that is "tons" literally) of strength.
Also these screws have a small enough shank diameter that they fit perfectly through the nylon spacers that are part of our gasket kit. The gasket kit is a good idea if you are connecting to concrete and you live in an area where there is freeze and thaw cycles.
Keeping water and moisture out of the screw holes in the concrete means less chance of the concrete splitting and cracking over the long term.
We also are going to be introducing a longer and bigger concrete screw called the GRK Caliburn XL concrete screw. It has over 3000 lbs of pull out force per screw but the shank is 19/64" and with the threads is a bit too big to fit through the nylon spacers so wont work with the gasket kit.
But you would only need to use 4 of them - one on each corner.
So the length of 2-1/4" is fine if you are going into concrete and they don't have to be 3-1/2" long.
I won an inflatable 6 person inter hot tub. I have a large deck. 12x 20 on both sides of the house. With a header to the house and the deck was built 6
I'm putting a swim spa into an inground concrete bunker and will build a deck around it. I have been advised to keep the deck joists a minimum of 6 inches