Need Advice What to Do with Retaining Wall

geek001 on 19/04/2016 - 16:18

Hi all,

I need some advice as to what to do with my retaining wall. It is bending outwards and is on its way to fall over. Some of the sleepers are rotting. The retaining wall in inside my boundary, but I think part of the cause of the bending over is my neighbours garage which is sinking into the ground a little bit. The retaining wall is not very tall, less than 1 metre high. It is unsightly at the moment, due to its bending and the rotting sleepers. I am thinking of doing something about it, but the question is what? If I have my way, I would tear down the retaining wall and build a new one. However, one of my friends advises me not to do that just in case in the process of rebuilding the retaining wall, the dirt underneath my neighbours garage gives way and I would be liable for the damage. His advice is not to touch the existing retaining wall but build another retaining wall just outside of the current retaining wall to "cover" it up.

What do you think?

FYI, I live within the Brisbane City Council area.

Home & Garden

Comments

  • maxpowers on 19/04/2016 - 16:51

    Do you have photos?

  • PVA on 19/04/2016 - 17:01

    contact a builder that does retaining walls and get a quote. a metre high can have a lot of weight behind it.

  • enzioFirenze on 19/04/2016 - 18:15

    also with your mate's suggestion, I would think the new retaining wall will get quick a large impact force when the old wall breaks

    • geek001 on 19/04/2016 - 19:21

      I dont think it will break suddenly but it will progressively worse and fall downwards instead because of the rotting. The existing retaining wall isnt very high.

  • oscargamer on 19/04/2016 - 18:26

    i think the sinking garage is more to do with the failing retaining wall than the other way around…..maybe?

    • geek001 on 19/04/2016 - 19:22

      I think it is unlikely. The only part of the retaining wall that is leaning outwards is the part where the garage is. Please refer to my photo above. Thanks

    • [Deactivated] on 19/04/2016 - 20:09

      Sounds sensible to me, the pic seems to indicate posts in the retaining wall were not deep enough, and as a result not doing its job. But I'm no expert!

      • oscargamer on 19/04/2016 - 20:13

        i'm not even convinced that pissy little structure is even a retaining wall / anything

        you need to know the bearing capacity/angle of the soil in question as well as the type of foundation of the adjoining structure

        what sort of soil do you have? sand? clay?

        how is the garage founded?

        • [Deactivated] on 19/04/2016 - 20:19

          Doesn't it have to have some force against it if it has moved a concreted metal post - suggesting it does have a purpose?

        • geek001 on 19/04/2016 - 20:28

          I am not saying that everything in my house is built properly. I have had a few wtf moments while renovating.

          The soil between the retaining wall and the garage seems to be just fill. Thats probably why nothing else grows on it besides hardy grass.

          The garage has a cement slab foundation from what I can see.

        • oscargamer on 19/04/2016 - 20:29
          +2

          @Gofast:

          yes, it looks like it MAY serve a purpose,

          but why should a structure from an adjacent building have to rely on an above ground structure in the OP's property?

          my post (hopefully) starts the conversation that the structural stability of the adjoining garage needs to be assessed

          how that is assessed and who pays for it, is another matter

        • geek001 on 19/04/2016 - 20:34

          @oscargamer:

          Yes.. all very good valid points. Hence the predicament I am in. What should I do? Contact the owner(the house with the garage is a rental) and sort this out the neighbourly way? This could potentially be a long and difficult process. Or just do what my friend says and and lose a few inches of useable space on my land and get on with my life?

        • oscargamer on 19/04/2016 - 20:36

          @geek001:

          i don't know

          what result do you want?

        • [Deactivated] on 19/04/2016 - 20:45

          @oscargamer:

          But wouldn't the retaining wall indicate that OPs property that is cut away?

          Personally I'd just replace the wall. I'd think it would be a small and cheapish job. Maybe if they do it bit by bit, with small distance between posts it minimises any risk when replacing? Again, I'm no expert! Good luck.

  • richox on 19/04/2016 - 20:45

    OP the parapet wall as shown seems newer than the retaining. it is possible the wall has its own retained foundation. Have you dug down the wall below the existing soil level to see how deep it goes? strongly recommended to do this and photograph for us.

    At any rate your neighbour is very likely at least 50% liable for the cost of suitable repairs. Potentially more depending on relative ages of construction of retaining and the wall depicted. What are these ages?

    There are generally easily available and digestable documents online that relate to residential boundary rules and regs - you can imagine hundreds of homeowners around the country every day are faced with just such scenarios. Give your council a call they will easily direct you to these material for QLD and your local council.

    At any rate start a dialogue with your neighbour ASAP as even small amounts of subsidence here could cause serious damage to their house.

  • altomic on 20/04/2016 - 06:58

    Some questions-

    Has the path(on the right of the photo) been excavated?

    Are these properties on a slope?

    How deep is the retaining wall?

    • geek001 on 20/04/2016 - 11:25

      Hi there, the path to the right is the side of my house, so I think the answer is no?

      Slope? Not really I guess, pretty flat or very minor slope.

      No idea how deep is the retaining wall. I am guessing not deep enough, maybe? seeing the posts are leaning with no signs of stress on the post itself.

  • kickling on 20/04/2016 - 08:54

    Are you talking about the bit covered in grass that is not very high? If yes, that is not structural. Your neighbours garage (ie red brick wall) would be on a concrete slab. Just take out the wooden sleepers and replace with your choice. It will be unlikely, given the distance from the garage and the wall-face line, that anything will collapse on their side.

    We did ours recently, but the retaining wall was under a fence plus very close to the neighbours house. It was a PITA because being so near their house there was a lot of gravel and bluestone which kept falling. Yours looks like it won't be troublesome.

    If you're talking about the sleepers under the fence on the left in your picture, it will be difficult as you need to remove the fence first, but again if you're careful and methodical it isn't super hard. But of course, hire someone if you're not confident. It won't be cheap if you hire.

    Here's our wall now :

    https://files.ozbargain.com.au/upload/107051/38777/dsc_4841.…

    • geek001 on 20/04/2016 - 11:22
      +1

      Wow, that looks really good, mate.

      Sorry, I should have been clearer, yes, it is the bit that is covered in grass. The posts are leaning over a little, not sure if you can see it in the picture. The brick wall is the neighbour's garage by the way.

      And no, I am not even thinking of doing anything with the retaining wall with the fence on it. That would be in the too hard basket. There is some rot on the retaining wall, but nothing too major and it is not leaning much.

      Ok, sounds like I should just get rid of the existing sleepers on the grassy bits and replace it with new ones. Just out of curiosity, why did you go with steel posts instead of wooden ones?

      • kickling on 20/04/2016 - 12:54

        Thanks. We actually did two entire walls, back and side. That photo is of the side. Three of us did 3 bays a day, working slowly but carefully.

        Your job will be easy. 2 people could do it under under 2 hours. There is nothing structural, so just remove and replace. Sure you will get same soil sliding down, but it's fine.

        The steel i-beams were already there from when the house was built. Our sleepers were untreated redgum or some kind of hardwood, used back in the early 90s. Back then they also used thick plastic sheeting to go behind the wall, which retained the gravel and stone on the neighbour's side, but unfortunately also trapped moisture on my side into the wood. This rotted the wood and allowed termites to easily come through, so we had to replace everything.

        If I had to build a wall I would use i-Beams anyway. Long lasting, easy to construct your wall, easy to replace any sleepers. If money was no object, I would go concrete sleepers but treated pine was required because I have odd length bays so had to individually cut to size.

        So please make sure you check for termites. Rotting wood (even if it's treated pine) will be attractive to them. This may result in you needing to replace the wall under the fence.

        http://www.doityourselftermitecontrol.com/termite-home-inspe…

        • geek001 on 20/04/2016 - 13:06

          I doubt I can get it done in under 2 hours with 2 people. Lol.. I am not that handy. I will need to replace the posts, as the posts are leaning. Also, if you look at the picture above, the sleepers closer to the ground on the left have rotten away completely.

          The retaining wall goes all the way past the fence, the retaining on the other side of the fence is ok and do not require replacing. The problem with that is that if I use 2.4m sleepers, the post holes will need to be exactly where the current holes are. So, I guess I will need to make one section 1.2m, so that the holes are in a different place. Do you think that is the way to go?

          Also, I got the house checked for termites when I bought it, there were evidence of termites along that wall, but has since been treated.

        • kickling on 21/04/2016 - 09:00

          @geek001:

          I would suggest looking at replacing as much as you would be comfortable with. The other sleepers you say are fine probably are of the same age? Therefore will soon need replacing anyway? But totally up to you. You will end up with mismatch retaining wall. However you can get around this by painting it all the same colour.

          You should dig out the existing posts (should be easy if rotten) and replace. Make sure you measure the bays. Then measure again to be sure. You don't want the hassle of cutting the sleepers. I don't have experience in dropping in posts but there would be a guideline as to the distance into the ground required depending on how high your post above ground is. Also unsure if you need to concrete them in… maybe the builder guy who commented below can help.

          The difference in H level ratings is the treatment dosage, for varying usage. Treated pine will still rot over time (nothing is forever) but will give you at least 20 years.

          http://www.thelogfactory.com.au/treatment_levels.aspx

  • windale on 20/04/2016 - 12:42

    Just make sure the posts and sleepers you get are treated. Not just for termites but for rot. Make sure your holes are deeper than your current ones and maybe space them closer together. Over engineer as the little extra on materials will mean it could last a lot longer and save you in the long run. There are also some great galvanized metal posts now that have slots in them so you can just slide the sleepers in. Make sure your posts (wooden or steel) are concreted in and have drainage at the bottom. Good luck

    • geek001 on 20/04/2016 - 12:57

      Thanks for the heads up. Question, I thought there are only one type of treated sleepers, is that right? Or are there different levels of treatment like structural timber, eg. h2, h2f, h3, etc. Or should I go hardwood?

      • windale on 20/04/2016 - 18:37

        You can get pine that's treated and is ok to put in the ground the stuff just treated for termites is not suitable for in ground use. I'm not sure of the ratings just google I guess.

  • goosegog on 21/04/2016 - 01:43

    As a builder firstly as your neighbour is on the high side it is his responsibility to fully support the ground on his side the retaining wall is his responsibility. If you don't want to fall out with him you should install a post and panel system on your side which you could carry out yourself, just do a small section at a time.. Good luck

    • geek001 on 21/04/2016 - 08:22

      It will be hard selling the idea of getting my neighbour to fix a retaining wall that is inside on my property(the grassy bits). The house next door is a rental. So you think I should just build put up another retaining wall in front of the current one and leave the current one alone?

      • kickling on 21/04/2016 - 09:02

        Yeah, you should speak to your neighbour (owner) first. Here there is no law stating they must pay half, it's just a common courtesy. Your State or council laws may differ.

  • dandandan on 21/04/2016 - 09:18

    There is a DIY retaining wall system call Rigdi which I saw on TV, they sell or distribute through Bunnings. I am going to use it myself, here is their website; http://www.ridgi.com.au/

    Maybe you could install this close to your existing retaining wall and just backfill the gap, so no need to pull the old one out.

  • diydave on 23/06/2016 - 10:58

    So important to get the foundation right when you're building a wall.
    I put some tips up on my blog last week - with tips on foundations, how far down you need to dig etc.
    Check it out: https://medium.com/@diydave/avoiding-an-epic-retaining-wall-…

  • BertieBrown on 23/06/2016 - 20:04

    You can definitely DIY retaining walls.

    It's cheaper and easier IMO to use RSJ's and sleepers.

    Obviously get quotes but IME it's quite expensive to get people in to build walls.

    If you can get hands on a concrete mixer, a PHD (be very careful of underground services and if you can get plans) and some mates, you could build a retainer that size in a couple of weekends easy I'd reckon. First weekend, dig holes and pour concrete with RSJ's, second weekend install sleepers.

    Largely soil should support itself, so either that wall doesn't have any (my guess based on its appearance) drainage, adequate drainage or there is some erosion issue going on with the shed, but I'd reckon it's just that water is building up behind the wall, it doesn't have anywhere to go and so it's rotting and warping. If you put a new wall in, all it's doing is basically holding the soil upright. Just make sure you put in adequate drainage with a new wall, and in QLD there may even be some regs on that considering how much water you guys get up there.

  • Name on 09/08/2016 - 19:09

    So it's been a few months. What did you end up doing OP?

    • geek001 on 09/08/2016 - 19:20

      Nah. Got given new priorities by the missus. Redid our backyard patio. Pulled it down. Got someone in to do the concreting. Then got a mate in to put up the patio from Stratco. Extending the driveway tomorrow. Got a mini mix truck coming tomorrow morning. Then putting up the carport. After that is done then I can come back to the retaining wall.

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