Results 1 to 11 of 11
  1. #1
    Join Date
    Jul 2010
    Location
    NC
    Posts
    122

    Default Deck support post on retaining wall

    The rear deck and side deck meet near the retaining wall. Three 4 x 4's were utilized at this area for support. Movement has occurred, thus front post is not plumb. Seems to be improper for a deck post to rest on a retaining wall. The third picture shows buckled siding where it appears that settlement and/or movement of the retaining wall has applied pressure to the wood trim.

    This home was constructed in 2002 and the deck must have been an owner installation. 6 x 6 deck posts were utilized at the front deck and looked ok.

    Your thoughts are welcome.

    Similar Threads:
    ***IMPORTANT*** You Need To Register To View Images ***IMPORTANT*** You Need To Register To View Images
    Crawl Space Creeper

  2. #2
    Join Date
    Nov 2009
    Location
    St Paul, MN
    Posts
    1,630

    Default Re: Deck support post on retaining wall

    It looks like the retaining wall has tipped, causing the buckling of the siding and the out of plumb posts. The deck will most likely need to come off to fix the retaining wall.

    MinnesotaHomeInspectors.com
    Minnesota Home Inspectors LLC
    ASHI #242887 mnradontesting.com

  3. #3
    Join Date
    Nov 2010
    Location
    CO
    Posts
    48

    Default Re: Deck support post on retaining wall

    You could use the retaining wall as a support if done properly.
    1st the retaining wall must have been built to hold a structure. It doesn’t appear
    this is the case because hydraulic pressure has already made it move.
    2nd the posts used needed to be isolated and secured to the retaining wall, and
    be properly secure to the deck.


  4. #4
    Join Date
    Jul 2010
    Location
    NC
    Posts
    122

    Default Re: Deck support post on retaining wall

    Quote Originally Posted by Jeff Langhorn View Post
    You could use the retaining wall as a support if done properly.
    1st the retaining wall must have been built to hold a structure. It doesn’t appear
    this is the case because hydraulic pressure has already made it move.
    2nd the posts used needed to be isolated and secured to the retaining wall, and
    be properly secure to the deck.
    I am going to call for further evaluation by a PE. There were some fairly large cracks in the retaining wall and the horizontal cracks can indicate future failure.

    ***IMPORTANT*** You Need To Register To View Images ***IMPORTANT*** You Need To Register To View Images

  5. #5
    James Duffin's Avatar
    James Duffin Guest

    Default Re: Deck support post on retaining wall

    Here is what the NC IRC says about retaining wall design:


    R404.1.3 Design required. Concrete or masonry foundation

    walls shall be designed in accordance with accepted engineering practice when either of the following condi
    tions exists:
    1. Walls are subject to hydrostatic pressure from
    groundwater.
    2. Walls supporting more than 48 inches (1219 mm)
    of unbalanced backfill that do not have permanent
    lateral support at the top and bottom.
    Included are retaining walls located on residential
    sites and any retaining wall systems that cross
    oyer adjacent property lines regardless of yertical
    hcight.
    3. Retaining walls that support buildings and their
    accessory structures



  6. #6
    Join Date
    Mar 2007
    Location
    Succasunna NJ
    Posts
    577

    Default Re: Deck support post on retaining wall

    If the deck is secured to the house, it looks like the siding was never removed. That's another no no.

    Darren www.aboutthehouseinspections.com
    'Whizzing & pasting & pooting through the day (Ronnie helping Kenny helping burn his poots away!) (FZ)

  7. #7
    Join Date
    Jul 2008
    Location
    Snowbird (this means I'm retired and migrate between locations), FL/MI
    Posts
    4,086

    Default Re: Deck support post on retaining wall

    The deck area to the right of the retaining wall appears to have a higher elevation over finished grade - cannot tell from photo perpective the projection or if a cantiliever (depth of field?). I presume a walk out basement or similar is below, suggesting this deck has an elevation far more than 4' over the area below and more likely exceeds 8' (on the right of retaining wall).

    If finished grade below is substantial - it would require far more substantial support than mere 4x4 posts.

    I do not see a cap or plate to distribute point load to block wall or pier, nor a means to retain/restrain position or resist forces.

    Last edited by H.G. Watson, Sr.; 02-04-2011 at 06:36 AM.

  8. #8
    Join Date
    Jul 2010
    Location
    NC
    Posts
    122

    Default Re: Deck support post on retaining wall

    Quote Originally Posted by H.G. Watson, Sr. View Post
    The deck area to the right of the retaining wall appears to have a higher elevation over finished grade - cannot tell from photo perpective the projection or if a cantiliever (depth of field?). I presume a walk out basement or similar is below, suggesting this deck has an elevation far more than 4' over the area below and more likely exceeds 8' (on the right of retaining wall).

    If finished grade below is substantial - it would require far more substantial support than mere 4x4 posts.

    I do not see a cap or plate to distribute point load to block wall or pier, nor a means to retain/restrain position or resist forces.
    Good day Mr Watson,

    I have attached a side view of this deck and support posts. Main support posts were 6x6's with cross bracing (bolted), the 4x4's were only utilized at the retaining wall.

    ***IMPORTANT*** You Need To Register To View Images ***IMPORTANT*** You Need To Register To View Images

  9. #9
    Join Date
    Sep 2009
    Location
    Rolla, MO
    Posts
    136

    Default Re: Deck support post on retaining wall

    Sidney

    I agree with Jeff a retaining wall if designed properly could easily support the deck. The short 4x4s are improperly attached at the top and bottom, but the real issue is not the deck. The retaining wall looks to be the most critical issue in your photo. It has some serious issues that need to be addressed.

    Randy Mayo, P.E.
    Residential Engineering & Inspection Services
    http://www.rlmengineers.com

  10. #10
    Join Date
    Feb 2008
    Location
    Chicago IL
    Posts
    2,048

    Default Re: Deck support post on retaining wall

    The retaining wall looks to be 6'+ high. Without proper tie backs into the earth behind it, the wall will do what it is doing. There's too much ground load behind it to keep it standing indefinitely. I always recommend a water tight finish cap on top of block walls like that; aluminum or overlapping treated 2x, etc. Without a cap, water just seeps into the wall and contributes to wall erosion. That wall has seen better days. I would write the wall as a collapse hazard.
    Partially supporting the deck on the wall is not a problem when conditions are good.
    4x4 Posts are NOT attached to either the deck or wall from what I can see. Don't wishy-wash is some 'improperly attached BS'
    The main posts also look to be sitting at grade, not elevated and without brackets.
    A good carpenter can fix the porch in a couple days. The wall is a bigger issue.

    www.aic-chicago.com
    773/844-4AIC
    "The Code is not a ceiling to reach but a floor to work up from"

  11. #11
    Join Date
    Mar 2007
    Location
    Las Vegas, NV
    Posts
    222

    Default Re: Deck support post on retaining wall

    Don't forget, once a structure such as a deck is attached to a dwelling it becomes subject to the codes pertaining to the dwelling itself (in my area at least). Thus, if the deck rests on a retaining wall such as the one in question, the wall becomes subject to applicable residential building codes as well. This includes things like, but not limited to, proper footings, wall support for type and height (as if it were a basement wall), and so on.

    Beacon Inspection Services
    Proudly Serving the Greater Henderson and Las Vegas Valley Area in Southern Nevada!
    Like Beacon On Facebook

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
  •