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Thread: Building a deck over septic....

  1. #1

    Default Building a deck over septic....

    This summer, I will be building a rather large deck off the back of my house. The deck will cover 2 septic tanks. The deck will end a few feet before the d-box and the leach lines won't be covered in any way. Has anyone built a deck over their septic tanks? What precautions did you take and what should I be aware of?

    Accessing the pump out lids: I have 3 possible options that I thought of. 1) Figure removable access ports into the deck plans. 2) Don't worry about the access ports. The entire deck will be put together w/ screws. So, removing a few boards once every 3 years isn't a major issue. 3) Construct a remote pump out.

    Ok, now #3 is something i made up and don't even know if it's possible. Here goes.... would it be possible to feed a permanent service line into the lid of the tank, run it along underneath the deck and have it exit the side where it is capped off and easily accessible by the pump out guys? Anybody ever see this or something similar done?

    Next question.... Before I build this deck, should I change out the lines that run from the house to the tanks? They are only about 1-2 ft below the ground and stretch for maybe 6 ft before they meet the tanks. The house was built in 64 and the septic man told me he believed the lines were original clay pipes. He recommended I change them before adding a deck. I'm not against it in any way. I just wonder if they might be better off left alone?

  2. #2
    Join Date
    Dec 2003
    Kent, WA


    I built a freestanding deck over my tank. It had 9 3x3 sections that lifted out and were strategically placed over the 3 access hatches. Things to consider:

    1. Keep all structure (i.e. posts) a few feet away from the tanks and piping. Do not set any weight bearing posts into the tank or lids.
    2. The access ports require visual access (especially the output port, as you need to check the baffle and replace it if it deteriorates, and look for back flow during a pump out to see if the drain field is failing). So just a hose solution isn't going to work.
    3. Build removable deck sections over the access ports. Design your deck so that they fit it (some kind of line or demarcation points for the lid area and just extend or repeat those so they don't look out of place). You'll be cursing about unscrewing boards once the screws have rusted and the heads strip (some of the crappier screws nearly strip when you put them in). If you take that approach, replace the screws with new ones each time you undo them. If you make removable sections, note that the decking ends tend to warp, so screw a board underneath near the ends to keep twisted decking ends from popping up in the middle of your deck.
    4. Replace the pipe from the house to the tank. Mine was ABS and not clay, but it still had cracked due to age and the tank settling a bit. Use sch 40 PVC or ABS for that new pipe. You'll need a concrete chisel and some concrete to do this if its a concrete tank.
    Kent, WA

  3. #3

    Default Video of how I approached this problem

    I wrestled with this for WEEKS... I finally just dove in (bad pun, I know...) and thought I'd figure it out along the way. Here's a short video of the approach and technique I took... Hope it helps...

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