Building a 14×24 Pier/Beam small house: My piers are in concrete!…
I’m building a 14×24 pier and beam. I have 2 beams that are held up by 12 4×4 posts, 6 on each beam. I made
the mistake of improperly creating a bearing surface. Instead, I dug deep holes (3 feet deep), put about 4″ of
gravel in the bottom of the hole, then put the treated 4×4 post on top of the gravel, and then I poured concrete
for about another 6 inches or so and then I put one of those 12″ diameter Quik Form Tubes on top of that and filled
the tube to the top. My piers are only 4 feet from each other so I tend to have a lot of piers and that’s good. The main
problem (if it is a problem) is that I don’t have much bearing surface at the bottom of each 4×4 (gravel then dirt). I’m hoping
that the adhesion of the concrete to the sides of the post is helping also. I have a few links where you can check out a diagram
I drew and also an actual picture of my ‘situation’. Mainly, is this ok or do you think I need to redo some things or even create
new piers? Here’s the links:
Replies
Have you calculated the bearing force of each post, and the weight of the structure which must be supported?
Fine
I think you are fine but for peace of mind you could nail a 2x4 on each side of the 4x4 to sit on the concrete. Next time just raise the 4x4 8"s and pour that or leave the 4x4 out and use a Simpson connector embedded in the 'crete.
KK
By pouring concrete around them you effectively turned your 4" X 4" posts into 12" posts. I wouldn't worry about it, you have plenty of bearing.
HI AJ,
As far as bearing, I would think you are ok. Hopefully the bottom of the hole was tamped well, crushed stone added and tamped too, then the post. I would be more worried about rot than the bearing conditions with a post buried in concrete (treated or not). To help keep rot at bay I would make sure the concrete around the post is domed to shed water quickly away from the post. If not poured that way, then I would spend some time with an angle grinder sloping the pier tops. The preferred method is to pour the piers a few inches above finish grade and then use a post base with a standoff that keeps the post's end grain away from the ground.
I'm a little curious as to what possessed you to do it the way you did.