A client asked me to re pour the caissons under their flagstone patio. The patio is supporting the posts for a large deck with screen room. They want us to temp brace the deck, tear out the flagstone, re-pour the caissons and re build the patio.
I'm completely unfamiliar with caissons (besides the googling I did yesterday) and am tying to get a feel for whether I can handle this project.
Is it even possible to re-pour a caisson??
Have you had similar projects??
What is the basic function of the caisson in this situation?? (to support the flagstone, which supports the posts??)
Caissons are essentially cylindrical shafts of concrete that go down to a bedrock or similar substrate to provide bearing. Most often used in places where expansive soils are present. Caissons are sometimes referred to as piers and I'm sure others.
Typical caissons are fairly deep, like I said, to get down to the bedrock. They can be formed with sonotube or drilled right into the soil.
If they are not very deep you could dig them up and repour them using sonotube. I would imagine for a patio that they wouldn't be very deep - 4' max most likely. I wouldn't imagine that the caissons are supporting the flagstone - only the posts.
And yes I have put in many caissons.. 200+ just finished the other day for a house - all 12". An office building had about 150 with some as large as 5' in diameter.
I would suggest placing them on top of something besides the flagstone. I would probably place the posts and then butt the flagstone to them. Otherwise I think you'll probably run into troubles down the road.
I assume the columns are wood? You could use a simpson galvanized post base and wrap the bottom with trim to hide it.
I was thinking about attaching them to new concrete footings and then hiding the footings with moss rock or something like that. We could also set the footings below the flagstone and like you said, do some trim work around the base of the posts to give them the appearance of sitting on the stone.
The customer also wants some 2x10's added to the beams supporting the deck to essentially make the beams thicker.This, adding new footings, temp bracing the large deck and finishing the trim and other misc woodwork, how much should I expect to pay to sub this out??
Could you suggest anyone in the Boulder-Denver area??
I haven't worked with many residential contractors in Colorado.. mostly commercial.
The framing / trim would be fairly minimal - largest expense will probably be the footings - maybe $500 as a guestimate.
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