Garden - car inspection pit idea

Discussion in 'Garden Projects and DIY' started by clueless1, Jan 11, 2014.

  1. clueless1

    clueless1 member... yep, that's what I am:)

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    I've done next to nowt with my front garden, mainly because I can't decide what I want to do with it. I have a few ideas. One plan is to move the pond from the back garden to the front. Certainly I also want to add a bit more 'structure' because I'm not generally a fan of flat gardens (awkward when you choose to buy a house in one of the flattest parts of the country).

    I also want to tackle more of my own car maintenance, and I don't trust jacks or axle stands enough to crawl under a tonne and a half of steel.

    So, I had an idea. I could so a sort of sunken pebbled area in a nice sweeping curve from the end of my drive, round onto the lawn. Nice sand stone walls to hold all the surround garden out, and lots of nice planting and the pond around it. 99% of the time it would just look like a garden. Somewhere nice to sit out. But on the rare occasions when I want to be under the car, I could simply drive it over the sunken pebble bit, and I'd then have enough room to crawl underneath.

    Any thoughts?

    Excuse my rubbish drawing skills, but this is something roughly like what I had in mind.

    Front garden.png

    The big block of red on the right is my very bad approximation of my drive. The house is just off the bottom end of my pic and the main street just off the top of the pic. All the white area would be planted up with shrubs and flowers, and the small pond would be shallow under the window, and deeper in the corner for the fish. None of the pic is to scale. The yellow bit would come down gradually getting deeper as you come off the drive, while the earth excavated to make that happen would be used, along with some sandstone rocks I have, to raise the ground gradually, so that the net effect would be the car drives up, straddling that area, while the ground underneath gets lower. 99% of the time, it would simply be our area among the garden plants to sit and enjoy it, so it wouldn't look like an inspection pit at all. I'd presumably have to do something to ensure the sides don't simply fall away if I put the car on it, but I guess that would be easy enough.
     
  2. Fat Controller

    Fat Controller 'Cuddly' Scottish Admin! Staff Member

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    Needs a lot of thought - firstly as you rightly point out, it would need significant support to stop the sides collapsing with the weight of the car bearing down on it. For safety, I reckon you are looking at either railway sleepers or RSJ's driven in vertically around the perimeter.

    Drainage is going to be another big issue - a hole in the ground is just asking to be filled with rainwater, which could in turn be a sod to deal with. And on that note, you have to make sure you have a fail-safe method for collecting any fluids that come out of the car - none of them, not even coolant are nice or healthy in least, and absolutely MUST be disposed of properly.

    Then there is the question of power - I presume that you will be looking at using an extension lead for lighting and power tools, but before doing so question whether this is the safest way of doing it.

    And there is access - if the ground slopes gradually into the pit, how are you going to get in and out from under the car?

    Finally, how are you going to make the area safe for the times when it is not occupied by the car - it will require some sort of 'lid' that is heavy enough to stay put and support any weight that goes over it (can you imagine the lawsuit if a washing machine delivery man ended up in your pit with your new washing machine on top of him?), whilst still being light enough for you to remove easily to access the pit.

    Personally, I would invest in a couple of top drawer trolley jacks and a couple of sets of over-capacity axle stands and then make myself a nice, flat, hard area to work on at ground level

    EDIT - bear in mind how easy it would be to disguise a concrete area with planters etc?
     
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    • clueless1

      clueless1 member... yep, that's what I am:)

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      It wont need a lid, it will be no deeper than about 18 inches. That's plenty enough to slide under the car for such mundane tasks as whipping the oil filter off or getting to the drain plug. Its about the clearance that I'd get if I put it on them rather dodgy steel ramps that someone tried to ban a few years ago (because cars were rolling off them and squashing people).

      I also wouldn't worry about drainage. The front garden drains very well as it is, and on days of higher than usual rainfall, it wont matter if it turns into a big puddle for a few hours. In fact it would probably do the neighbourhood a favour, as water collecting there wouldn't be racing off to overwhelm the drains.

      You're right about catching anything that spills off. Brake juice and oil being the biggest risk ones, as I can do the coolant without lifting the car, just working under the bonnet, and its easy to catch because you just disconnect the top hose first, get as much as you can out that way, then do the bottom hose. I never bother with a full flush because if you keep on top of coolant changes, you don't need to.

      Getting in and out is easy. I'd just plan for a suitable gap between the front of the car and the end of the 'pit'.

      Supporting the sides is the biggy. That will take some thought. If I go for this plan, I'll probably actually build the walls with rocks and mortar, and kid of slop them if you know what I mean.
       
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      • Scrungee

        Scrungee Well known for it

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        Is that 'pebbled area' going to be permeable construction? If not it would appear you'd require planning permission.
         
      • clueless1

        clueless1 member... yep, that's what I am:)

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        A pebble floor would indeed be permeable.
         
      • Fat Controller

        Fat Controller 'Cuddly' Scottish Admin! Staff Member

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        For what its worth, I agree that the drive on ramps are less than useless, and downright dangerous also - I'd much rather spend a few quid more and have the best axle stands I could get and two trolley jacks.

        I'm not convinced that bricks and mortar would be strong enough to cope with the loads upon the sides, bearing in mind that the car will be pushing down with its weight and the soil behind would be wanting to push inwards; I really do think that some sort of RSJ/lintel affair driven into the ground is going to be needed. If you are looking at an above ground depth of 18 inches inside the pit, I would want at least 18-24 inches of the chosen support below the ground level - that should stop the blighter caving in.

        I would still be cautious with an 18-inch deep hole in your front garden that is unprotected - even if the trench is sloped - - how will you prevent people falling into it? 18-inches is enough to break an ankle or leg if you get it wrong?
         
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        • clueless1

          clueless1 member... yep, that's what I am:)

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          Its lower than my garden wall, which people could also fall off, but one must ask, what were they doing on it in the first place?

          But I might sack the idea anyway. Thinking some more, it does seem like a lot of effort for something that would get very little use. More thinking to do I reckon.
           
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          • Fat Controller

            Fat Controller 'Cuddly' Scottish Admin! Staff Member

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            Sadly, the world doesn't work the same any more - where there is an injury, there is almost invariably a claim, whether they should have been doing what they did or not. I know of a case where a drunk individual opened the rear doors on a moving bus, jumped out, and hit a parked car that the bus was passing - clearly the fault of the individual, but still a claim was lodged for compensation against the bus operator. You really could not make it up.
             
          • Scrungee

            Scrungee Well known for it

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            I asked because a "pebbled floor" (as shown on the design) normally looks like this, unlike a pebble bed which would be a (permeable) bed of pebbles.

            pebbles.png
             
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            • JWK

              JWK Gardener Staff Member

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              I'm with FC on this, it's a little risky and also the pebbles will be most uncomfortable to crawl about on.
               
            • rustyroots

              rustyroots Total Gardener

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              Unless your working on cars every week it seems like a lot of work and potential grief to get right. And as already stated if someone does injur themselves then you will get taken to the cleaners. I think you would be better off with a couple of decent trolley jacks and stands.

              Rusty
               
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              • clueless1

                clueless1 member... yep, that's what I am:)

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                Sorry, my mistake. To me, pebble floor means literally pebbles spread over the floor. I guess I meant pebble bed.
                 
              • raebhoop

                raebhoop Gardener

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                I think it's a great idea...should the car drop on you.... just fill the hole in and stick a pot of flowers on top....job done. :hapydancsmil:
                 
              • shiney

                shiney President, Grumpy Old Men's Club Staff Member

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                You're right that the supporting walls would need a lot of work and thought. With good draining land (as you say yours is) there's the possibility that the water drainage will undermine the vertical supports that you would need. This would require even deeper supports and, to be on the safe side, they would need cross beams below the gravel area. They would brace the sides and help offset the horizontal stress points created by the pressure of the wheels.

                Although the land may drain well you will get seepage from the ground surrounding the 'pit' as it would be the direction of least resistance. So the 'pit' is likely to be wetter than the ground either side.
                 
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