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So the wedge shaped concrete pad thats right up against the house; April 17th, we're having air conditioning installed before it gets to hot out. According to the installer, the unit will fit on the pad, about 1 foot away from the water supply and electrical box.

He's ok with that (a professional Lennox dealer) and I want it on this side of the house as well because we have plans for a patio off of the back of the house. But, to give myself some peace of mind, can I square off the wedge shaped concrete with more concrete?

I'd like to build a form (make the wedge into a rectangle), go and score some quikcrete from Home Depot and pour it myself. 5-10 bags? Then they can put the unit closer to the left side of the window (and farther from the water / electric meter)

Do I need to tie it into the existing driveway / wedge? Wire mesh re-bar inside of the concrete or no?

The only load it'll have is the AC unit. Maybe I build a shed type enclosure over it and keep recycling inside of it (we keep our recycling outside)

Any suggestions? I have 2 weekends to accomplish this; and its hovering around 45 - 55 degrees right now. Not the optimal temperature to pour concrete, but its so little.

  • Related - diy.stackexchange.com/questions/5991/extending-concrete-slab
    – ChrisF
    Mar 26, 2012 at 21:51
  • Also related - diy.stackexchange.com/questions/12942/…
    – ChrisF
    Mar 26, 2012 at 21:53
  • Instead of all the concrete, what if you have the installer bolt down some angle iron first, then mount the AC on that. That way it could cantilever out a bit...and save you all the hassle of pouring concrete.
    – DA01
    Mar 27, 2012 at 0:40
  • I've seen on newer homes such as my brothers that was built just a few years ago, they put it on a platform and bolt the platform into the house, about 2 feet off of the ground. I had originally suggested doing this but hes concerned with vibration; which I agree. The only problem with using angle iron off of the main pad is there not being enough surface area to attach to. The wedge gets pretty narrow where I want to put it (under the left side of the window or even closer to the back of the house)
    – lsiunsuex
    Mar 27, 2012 at 15:43

1 Answer 1


Assuming both existing concrete pads are stable, I see no problem adding whatever bit of a pad you need for an AC unit. Do you ever see them move independently during the spring thaw? Just leave an 1/8 to 1/4 inch expansion joint between the new concrete and the pad you are trying to match level with. Simply frame up a form with plywood cut to proper height, support the sides with a few blocks so they will stay straight, pour some sacrete and screed it smooth. Float it after it starts to set up if you want a smoother finish. I'm quite sure you will be fine.

  • 1
    Through the 3 winters we've been here I haven't seen any shifting. Everything appears to be pretty stable. Thank you for the suggestions. Weekend project!
    – lsiunsuex
    Mar 26, 2012 at 23:12

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