(206) 949-5683, Top Rated Plumber, Seattle
Results 1 to 10 of 10

Thread: Questions on pouring concrete around new rough-in

  1. #1

    Default Questions on pouring concrete around new rough-in

    I moved my rough-in in my basement about 10 feet. I've already rerun the new pvc and I'm about to pour the new concrete back into the trench I dug. Are there any things I should consider before pouring? I'm going to use cardboard around the toilet drain to create the space needed for the flange to fit. Can the concrete be poured right around the new drains? Do I need to replace the vapor barrier? Should I put gravel back into the holes here the drain isnt? should I replaced the wire that I cut out ( the trench is about 12 in wide)? Is there a specific type of concrete I should use? And finally,should the concrete be poured all at once?

  2. #2
    Master Plumber Redwood's Avatar
    Join Date
    Dec 2007
    Location
    Connecticut
    Posts
    7,463

    Default

    Have you had it inspected yet?

  3. #3

    Default

    yes, its been inspected.

  4. #4
    Geologist sjsmithjr's Avatar
    Join Date
    Dec 2005
    Location
    Knoxville, Tennessee
    Posts
    295

    Default Concrete

    Are you planning on bag mixing or having it delivered? Did you saw cut the existing slab? Where are you located (state would be close enough)?
    Last edited by sjsmithjr; 08-28-2008 at 11:30 AM.
    -Sam Smith
    Licensed Professional Geologist - AL, TN, KY

  5. #5
    Master Plumber Redwood's Avatar
    Join Date
    Dec 2007
    Location
    Connecticut
    Posts
    7,463

    Default

    Also you have refilled the hole...
    How have you compacted the earth?

  6. #6

    Default

    I live in Maryland. I was going to mix bags. It's an area of about 12 feet long and 1 feet wide. Honestly, not a lot of dirt came out of the hole. It was about 4-5 inches of concrete and another 5-6 inches of gravel. I used a saw for some, but mostly a jack hammer.

  7. #7
    Geologist sjsmithjr's Avatar
    Join Date
    Dec 2005
    Location
    Knoxville, Tennessee
    Posts
    295

    Default

    You started out with approx. 4 inches of gravel, a vapor barrier to prevent water vapor and radon migration, and wire mesh to make the 3000 psi slab resistant to cracking.

    I would but the soil back in excavation, compact (hand tamper), put the gravel back in, compact, put the vapor barrier back in, and use 5000 psi high early strength bag mix. If the sand is dry, you may need to wet it a bit to get good compaction. You want the grains to stick to each other; you can make a golf ball sized clump by hand to check. Use the 5000 psi bag mix because when you mix concrete in a wheelbarrow, you rarely achieve the rated strength. Try to resist the temptation to get the concrete too wet.

    Unless you can tie the new wire to the old, I don't think your trench is wide enough to require replacement. If the existing concrete is sufficiently rough (like you'd get from using a demo hammer), the new concrete will key in and won't settle. If you have sections that are slick from top to bottom, consider roughing it up. I don't think it will be necessary to use rebar dowels, but I haven't seen it and I don't know how well the underlying fill will be compacted.

    Someone is bound to come along and say this is overkill, but this is how I would do it.
    Last edited by sjsmithjr; 08-28-2008 at 03:52 PM.
    -Sam Smith
    Licensed Professional Geologist - AL, TN, KY

  8. #8
    Master Plumber Redwood's Avatar
    Join Date
    Dec 2007
    Location
    Connecticut
    Posts
    7,463

    Default

    Overkill is a good thing!

    For compaction of earth I like to use water.
    I soak until there is a puddle then poke it with a broomstick until the water disappears, repeat and repeat until its not soaking in anymore.
    Then let is sit overnight and it is then about as compact as it can get.

    Where the new concrete is meeting the old I use a concrete bonding agent.
    http://www.google.com/search?hl=en&q...+bonding+agent

  9. #9

    Default

    Thanks guys, edge is pretty jagged, so the new concrete should "key" into the old pretty well. I don't think I need new mesh because the tench is only 11 inches wide. I'll put the dirt and gravel back in and compact it. Is there a certain type of tape that I should use to replace the new plastic to old?

  10. #10
    Geologist sjsmithjr's Avatar
    Join Date
    Dec 2005
    Location
    Knoxville, Tennessee
    Posts
    295

    Default

    Quote Originally Posted by Vinniejt76 View Post
    Is there a certain type of tape that I should use to replace the new plastic to old?
    At the local hardware look around the weatherstriping supplies for something like Frost King Polyethylene Tape.
    -Sam Smith
    Licensed Professional Geologist - AL, TN, KY

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •