What professional and/or tradesperson for a collapsing concrete floor?

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  • What professional and/or tradesperson for a collapsing concrete floor?
  • Premier Icon stilltortoise
    Subscriber

    The floor to the side of our house is made of huge concrete slabs, each approx 3 sq m. Over the years the ground beneath has presumably settled/moved and the blocks are no longer flat. We had a quote to remove them and get it tarmaced, but I want to make sure there isn’t an underlying cause for why they’ve moved that needs addressing.

    I’m not really sure what kind of professional I need to be looking for but I assume some sort of surveyor/engineer. Help please.


    Concrete slabs by stilltortoise, on Flickr

    MrSmith
    Member

    Massive sinkhole.
    Just sayin like.

    Premier Icon stilltortoise
    Subscriber

    Don’t joke. It has crossed my mind, which is why I’m happy to get a professional to have a look rather than just getting the builders in

    Premier Icon stilltortoise
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    *bump* for lunchtime crowd

    Premier Icon thepurist
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    It could just be that they’re a bit too thin and they’ve cracked as a result of normal loads, or at the other end of the scale Mr Smith could be right. How long have they been down? What sort of soil are you on? Any drainage in that area?

    You could go all out and call in a specialist geotechnical engineer to take a look, or maybe a building surveyor. Or you can just chance it and get a decent contractor (ie probably not the cheapest) to lay a properly constructed replacement…

    Premier Icon stilltortoise
    Subscriber

    They’ve been down for longer than we’ve been here (6 years?) but are steadily getting worse. There is a fairly sizeable drain beneath so I have enough reason to be paranoid concerned.

    Premier Icon thepurist
    Subscriber

    First step then would be to get someone to do a CCTV drain inspection.

    footstomper
    Member

    There can be a few reasons why this is happening.

    – The Concrete was substandard when fist laid
    – The Ground Conditions maybe soft i.e. Sand or similar
    – The drain may be leaking at one of its joints resulting in under washing the sub-soil
    – Water from elsewhere could be washing the subsoil away

    The only way of telling is by the removal of the slabs to expose the problem ( a surveyor will need this doing before he will give you a full report anyway). My advice would be contact a reliable Builder to remove the concrete and check for the problem, if he cannot give you a proper explanation then this is the time to contact a surveyor. I would guess that if you had a serious problem it would have happened a lot quicker than over a long period.

    Premier Icon stilltortoise
    Subscriber

    Thanks footstomper. That’s a very sensible plan of action.

    PS I did ring our local drain inspectors and they said the drains were too big for their equipment and would need specialists

    hooli
    Member

    I would just get a builders opinion and quote, keep in mind they probably wont be able to see much until they have started digging. Drain inspections are quite expensive, in my opinion the money would be better spent on sorting the issue out.

    Could also be just settlement over the years or worst case a partially collapsed drain. I don’t think either will bankrupt you.

    creamegg
    Member

    Drain inspections are quite expensive, in my opinion the money would be better spent on sorting the issue out.

    recently had cctv survey done, cost £75/hour (min charge £150 though)so not that expensive. (not London prices though)

    Premier Icon Squirrel
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    From that photo it looks like it might have been repaired in the past?

    Premier Icon stilltortoise
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    recently had cctv survey done

    I’ve explored that option, but the local firm only survey drains up to 6″ diameter. Beyond that requires (even more) specialist equipment apparently.

    Builder – one we know and trust – coming next week to do some digging.

    Thanks all. I hope I’m not on here next week asking “what do I do with a sink hole?” 😯

    marcus
    Member

    I’m presently sat watching a crew of guys pumping grout into old mine-workings beneath a concrete slab just like that.

    wrightyson
    Member

    What size drain is running on your property bigger than 150mm and how do you know?
    And fwiw I reckon i can see three separate repairs, if these weren’t dowelled you’ll always get separation like that.

    Premier Icon Speshpaul
    Subscriber

    I’m presently sat watching a crew of guys pumping grout into old mine-workings beneath a concrete slab just like that.

    shouldn’t you be watching where its going 😆

    Premier Icon Speshpaul
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    you’ve got a old path next to the house with a some light coloured repair- Drain?
    then the main slab- car parking? with a larger more recent repair in a wet mix.
    i think theres a good chance you’ll find that the concrete has been laid on earth and has just collapsed.

    Premier Icon slowoldgit
    Subscriber

    If it’s a big drain, then is it serving several properties? Which would make it the water (sewerage) company’s problem, not yours. There’s been a change in the law. Time to lift a few manhole covers, maybe.

    Premier Icon thepurist
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    Surely bigger drains should be easy? Go-Pro, puppy, DX light and a can of Pedigree Cham dangling from the next inspection cover…

    Premier Icon wwaswas
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    I’m presently sat watching a crew of guys pumping grout into old mine-workings beneath a concrete slab just like that.

    it was always going to end badly and it makes a change from using motorway bridges to hide the bodies.

    Premier Icon stilltortoise
    Subscriber

    What size drain is running on your property bigger than 150mm and how do you know?

    We have a manhole cover under the fruit patch that leads to a huge access “hole”. It’s at least 2m deep and from there I can see a large culvert heading across the garden which is 40/50cm diameter. At right angles to that – I suspect running under the concrete – is a smaller drain that’s still small-dog-with-a-headcam size.

    I have put in a request to Severn Trent to see if they can do anything. If they can tell me the drain is not immediately under the concrete it may set my mind (slightly) at rest.

    mogrim
    Member

    Surely bigger drains should be easy? Go-Pro, puppy, DX light and a can of Pedigree Cham dangling from the next inspection cover…

    Or a small child, bribe it with sweeties. There are lots available at your local primary school, head along and see if you can find a volunteer?

    wrightyson
    Member

    We once lost a remote cam down a 450/500mm run. It dropped into a hole 17 m from the mhole,where the pipe had cracked and dropped away. Cue nutcase drain dude doing a “man entry” I got them to sign every disclaimer I could find before he went in. Md from the company out etc. Not a job I’d have done!

    sharkbait
    Member

    I suspect that you could be in for a bit of a hefty bill at the end of all this.
    Just breaking up and carting away some of the existing slab is going to cost a few hundred. Chances are it’s just settlement but you’ll need to break up all the slab, cart it away, investigate the drain, backfill (with a bit of material needing to be added), compact and pour a new slab with steel reinforcing this time around.

    Premier Icon molgrips
    Subscriber

    Jump up and down on it. If you manage to climb out of the resulting hole you can use it to dispose of all the broken concrete. Win.

    oldschool
    Member

    And make the flicker album private.
    Skiing does looks good though.

    beicmynydd
    Member

    Can’t you dig up the concrete yourself, hire a hydraulic breaker from your local tool hire shop over the weekend.

    twinw4ll
    Member

    You and your family are having waaay too good a time.
    Fun police have been called and are on their way. 😥

    pjm84
    Member

    Can’t you dig up the concrete yourself, hire a hydraulic breaker from your local tool hire shop over the weekend.

    plus 1000

    Don’t worry. I’ve seen new concrete crack. Lets sum it up:

    No reinforcement
    Poor mix
    Poor bay sizes / length to width ratio
    Poor sub base
    Age
    Thickness
    Oversite

    Premier Icon stilltortoise
    Subscriber

    You and your family are having waaay too good a time.

    lol we try. Having fun with the family is the reason I’d rather get someone in to do this than spend my weekend labouring. Maybe when they’re older I’ll let them play with me and a hydraulic breaker 😆 There will come an age when my boys don’t want to spend time with me. Until then…

    Fun police have been called and are Third child on their way

    That should put paid to fun for a while *gulp*

    Premier Icon lowey
    Subscriber

    Can you post up some more pics showing the whole area and perhaps a sketch plan showing location and possible line of drain… email me if you want.

    I deal with this stuff all the time.

    Premier Icon stilltortoise
    Subscriber

    Yep, will do so later today. Thanks

    Premier Icon stilltortoise
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    Looking down the drive to the main road:

    Looking back the other way. The huge manhole is under the soil in the “fruit patch” (it is in the Summer) just right of centre at the top of the pic. The drain heads down under the fruit patch and somewhere under the car port and drive to the road. The culvert I referred to heads left under the lawn from the fruit patch and into next door’s garden. There are a number of smaller land drains feeding at right angles into this culvert from the field behind.

    FunkyDunc
    Member

    If it’s a big drain, then is it serving several properties? Which would make it the water (sewerage) company’s problem, not yours. There’s been a change in the law. Time to lift a few manhole covers, maybe.

    We had water leaking from drain problem. Contacted the local water authority. They had plans of our house on their screen and could see which drains were theres and which were our responsiblity.

    If they cant see it on screen then ask them to send an engineer out to check whats what.

    Basically if its a pipe that purely serves your house then likely yours to deal with. If other houses stuff goes through it, its theirs.

    Push them harder to do some thing.

    The guy who came out to ours was actually very helpful, even though it ended up being our issue.

    Premier Icon stilltortoise
    Subscriber

    I don’t know for sure yet if it is a drain problem. We’re going to take up some of the concrete and have a look first. If it is the drains I will knocking very hard on Severn Trent’s virtual doors because this most certainly is a drain serving multiple properties.

    FunkyDunc
    Member

    I wouldnt even do that. Just ring them up saying your ‘patio’ is sinking and you think their drain runs underneath it.

    Looking at their plans they will see straight away if it runs underneath. If it does then they will have to investigate.

    Whats to loose apart from the cost of a phone call as opposed to shelling out a load of cash

    Premier Icon stilltortoise
    Subscriber

    I’ve already contacted them but I’m sat in a queue of other people who’ve probably logged similar requests.

    Premier Icon lowey
    Subscriber

    Sorry forgot all about this.

    No issue with drainage IMO. Your concrete has just cracked. There are multiple slabs that have been cast at different times, with no expansion joins / construction joints. If it was my guess, you sub base has settled a few mm and cracked the concrete. Also the combined actions of the weather will have caused it to crack and water can seep into your sub base causing settlement. Concrete, no matter how well its laid will crack over time. Rip it up, make sure you spec a good sub base (200mm MOT 1 or such) making sure its properly compacted, the put a new finish on top. I really dont thing you will have any problems *

    * all based on pics, dont sue me when your house falls down.

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