Hey everyone. I'll do my best to explain this.
BLUF:
I poured a small 3.5" deep pad, and 12" deep footer for some deck steps. I used expansion joint strip material between the new pad and the existing walkway, BUT the pad is flush against a few of the deck's 4x4 support posts on the opposite side, which are sunk in concrete in-ground. I am concerned about possible expansion of the new pad toward the deck, causing issues with the 4x4 posts. Also concerned about cracking elsewhere and learning how I could have done it better for next time.
Detailed background:
I have a floating deck with in-ground posts in concrete footings, built before we bought the house. The stringers from the deck's steps were previously sitting on bare ground and had sunk about 3-5" or so over the years. There is a pre-existing 3.5" thick sidewalk/landing in front of the steps. The rail posts (4x4's) of the deck steps were sunk in concrete, but had warped dramatically and I decided to pull them out to redo them while I was redoing other parts of the deck.
Prep:
Once the steps were removed, my plan was to pour a proper footing for them (12" thick x 12" deep x ~70" wide), and a 3.5" thick pad connected to the footing going back toward the deck, just to keep things tidy. We have dogs, and they tend to run behind the deck steps and dig, which is a nuisance, causes water pooling, etc. We could have just blocked off the steps, but figured if I was doing concrete anyway I might as well do the pad.
I've never done much concrete, so I spent some time googling and figured that other than the footing, this would mostly be cosmetic and not be a huge problem if I screwed it up (the steps would eventually cover 90% of it, anyway), and no matter what, it would hopefully be better than it was before, at least structurally.
I pulled the 4x4 posts with a farm jack, dug the trench for the footing, and excavated the area for the pad, flush up to the existing deck posts, and out a bit into the existing sidewalk to be able to tie it in a little more neatly. I added a compacted 4" base of gravel (ABC). I used wire mesh for the pad, and I used rebar in a way I figured made the most sense to me, based on some googling. I now understand rebar doesn't do much with regard to preventing cracks, so some of my work in this respect was likely misguided. I also added an expansion strip between the new pad and the old walkway.
Rebar:
Originally I had thought about pouring the pad completely around the deck posts, but was concerned with heaving/movement. After the fact, I've learned a better way of doing this, framing a "diamond" around the posts and filling it in after, but alas...
So this was all done in one pour, from deepest to shallowest:
Pictures can probably explain it better. I don't plan on redoing any of it unless there's a critical issue, but I am interested in learning what I could have done differently, and/or if there's anything I can do now after the fact to make things better, especially with regard to the butting surfaces between the new pad and the deck posts.
QUESTIONS:
BLUF:
I poured a small 3.5" deep pad, and 12" deep footer for some deck steps. I used expansion joint strip material between the new pad and the existing walkway, BUT the pad is flush against a few of the deck's 4x4 support posts on the opposite side, which are sunk in concrete in-ground. I am concerned about possible expansion of the new pad toward the deck, causing issues with the 4x4 posts. Also concerned about cracking elsewhere and learning how I could have done it better for next time.
Detailed background:
I have a floating deck with in-ground posts in concrete footings, built before we bought the house. The stringers from the deck's steps were previously sitting on bare ground and had sunk about 3-5" or so over the years. There is a pre-existing 3.5" thick sidewalk/landing in front of the steps. The rail posts (4x4's) of the deck steps were sunk in concrete, but had warped dramatically and I decided to pull them out to redo them while I was redoing other parts of the deck.
Prep:
Once the steps were removed, my plan was to pour a proper footing for them (12" thick x 12" deep x ~70" wide), and a 3.5" thick pad connected to the footing going back toward the deck, just to keep things tidy. We have dogs, and they tend to run behind the deck steps and dig, which is a nuisance, causes water pooling, etc. We could have just blocked off the steps, but figured if I was doing concrete anyway I might as well do the pad.
I've never done much concrete, so I spent some time googling and figured that other than the footing, this would mostly be cosmetic and not be a huge problem if I screwed it up (the steps would eventually cover 90% of it, anyway), and no matter what, it would hopefully be better than it was before, at least structurally.
I pulled the 4x4 posts with a farm jack, dug the trench for the footing, and excavated the area for the pad, flush up to the existing deck posts, and out a bit into the existing sidewalk to be able to tie it in a little more neatly. I added a compacted 4" base of gravel (ABC). I used wire mesh for the pad, and I used rebar in a way I figured made the most sense to me, based on some googling. I now understand rebar doesn't do much with regard to preventing cracks, so some of my work in this respect was likely misguided. I also added an expansion strip between the new pad and the old walkway.
Rebar:
- Two horizontal pieces at the bottom of the stringer footer
- 1 horizontal piece near the top of the stringer footer, bent @ 90 degrees down into the excavated post-hole
- 1 horizontal piece spanning from the back of the pad (near the deck) into the "outcrop" piece joining the new pad to the pre-existing walkway.
Originally I had thought about pouring the pad completely around the deck posts, but was concerned with heaving/movement. After the fact, I've learned a better way of doing this, framing a "diamond" around the posts and filling it in after, but alas...
So this was all done in one pour, from deepest to shallowest:
- Filled in post-hole from old post - approx 12"x12"x24" depth
- New Stringer footing, adjacent to post hole - approx 12"x70"x12" depth
- New Pad - approx 40"x70"x3.5" depth
- Small "outcrop" to cosmetically connect new pour to pre-existing walkway
Pictures can probably explain it better. I don't plan on redoing any of it unless there's a critical issue, but I am interested in learning what I could have done differently, and/or if there's anything I can do now after the fact to make things better, especially with regard to the butting surfaces between the new pad and the deck posts.
QUESTIONS:
- Any critical issues?
- What could I have done better? A different order of pour?
- Are the various depths a problem? i.e. having the deep post hole "connected" to the shallower footing, connected to the even shallower pad and "outcrop". Do these different pour depths create stresses that generally should be avoided? What would be the better way to do it?
- I have expansion material between the new pad and the old walkway, but not between the new pad and the pre-existing deck posts. There are 4 posts I am concerned about, totaling about 14" of total contact surface. Should I be concerned about this? If so, is there anything I can do after the fact to address this?
- I assume the skinny "outcrop" is ripe for cracking. I forgot to put a control joint running parallel to the expansion strip (see pic). Can I cut a control joint there after the concrete has cured (about 72 hour post-pour as of this writing)?
- Bonus question: The mix was too dry. I wasn't able to float/finish it very well at all. I'm not too concerned with the cosmetics since it will all be covered, but can I use a bonding primer and float a new finish on top later down the road if I were so inclined?
