Viewing 29 posts - 1 through 29 (of 29 total)
  • Any builders or drainage specialists that can answer a question about soakaways?
  • peter1979
    Free Member

    To try and keep a long story short, we have structural issues with our house that our insurers are being unhelpful with.

    They have said we need to improve the rainwater drainage by building soakaways to the front and rear of our property as it appears they discharge straight into the ground and the ground around our foundations is damp.

    This isnt covered by insurance (suprise suprise).  It needs to confirm to building regs but this means a soakaway needs to be 5 metres from property.  This is an issue at the front of our property as the garden is only 3.5m deep until it reaches a footpath. To the rear it is possible, but we can’t divert the front rainwater to the rear really.  So what happens in this case?

    Before anyone asks, there is no rainwater drainage plans for the house/street and plans from the water company only show sewer system via the back garden.  The insurance company apparently surveyed the drains but couldn’t tell me where the rainwater goes, only the sewer.  House is 1930s build.  Neighbours don’t know where their rainwater goes when it goes into the ground either and they look to be having some structural issues as well.

    What I think I’m asking is, how do you build a soakaway and confirm to building regs when the garden doesn’t really lend itself to being able to?

    We approached a drainage company and they quoted for soakaway installation and it was an eye watering cost.  They didn’t seem to be bothered that it would t be 5m from the house.

    nickjb
    Free Member

    My understanding is that 5m is best practice but if it is not possible then it can be less.

    swdan
    Free Member

    From my knowledge of part H you can’t be within 5m so you won’t be able to build one at the front. I don’t believe there is any compliant way around these. You could always speak to local building control and they might be helpful If they actually have anyone there.

    If you did build one you run the risk of the same problem you currently have i.e. damp soil around your foundations. In theory you also need to do percolation tests to be able to size the soaksway appropriately. I would question whether whoever came out and have a look at it understands the problem and what a “Soaksway to building regulations” actually is.

    pk13
    Full Member

    My last house had similar but a longer garden thin and long garden that backed onto network rail tracks (they don’t play nice with home owners)

    The only thing that worked was a French drain into a pond with perforated liner and a banked rear section so the water didn’t seep onto the embankment.

    The front was straight onto the street so the gutter just poured onto the path like all the other houses.

    It worked for that house as the soil was surprisingly clay free.

    mc
    Free Member

    To answer your question about where the existing rain water goes, given the age, probably a very small and quite crude soakaway directly at the bottom of the down pipe.

    And it will have most likely filled with soil by now, so probably won’t be doing that much.

    Edukator
    Free Member

    Soil type and geology? If you have permeable soil over porous/permeable bed rock then a soakaway is easy: dig a hole, fill with gravel and run your surface water into it. Heavy clay soil over impervious bed rock – you’ll create a gravel filled pond.

    You can sometimes reverse gutters to get the water from the front to the back of the house, I’ve done that.

    peter1979
    Free Member

    The ground investigations we had by the insurance company say the soil is a clay, silt and sand mixture.  Unsure of bedrock but there were bits of granite within in the soil.  No perculation tests has been done.

    I could potentially reverse the guttering to divert the rainwater to the rear.

    Rich_s
    Full Member

    This isnt covered by insurance (suprise suprise)

    What isn’t covered by insurance?

    And why?

    ads678
    Full Member

    TBH, it’s not the right thing to do, but I’d put the down pipe into a back inlet gully and connect that to your foul drainage. It’s what happens in most houses up to about 10/15 years ago. Just don’t tell anyone….

    If you’ve got clayey soil a soak away is never gonna be great, although as said earlier the downpipes probably drain straight into really old soakaways that don’t work any more so getting them away from the he building will be better than what’s happening now!

    The 5m thing is a best practice thing, pretty strict but I’ve had a few approved in the past that have had to be closer to a building. I’ve not worked in drainage design for about 5 years now though.

    Squirrel
    Full Member

    Might be worth mentioning to the insurers that it didn’t contravene Building Regs when it was built, and B Regs are not retrospective?

    peter1979
    Free Member

    What isn’t covered by insurance?

    And why?

    We have got subsidence and it is not certain what is causing it at the moment, but the insurance company have appointed a subsidence expert who has said that soil is damp at our foundations and this is likely due to failed rainwater drainage front and rear. They want us to repair/improve this before the claim can continue and rainwater drainage is not covered under insurance, only foul drainage.

    Ewan
    Free Member

    Can you ask for a second opinion? Subsidence in clay soil is normally vegetation related (which causes the soil to heave or shrink). What mechanism are they proposing that the water is causing the foundations to move?

    That said. As someone said above a lot of people would suddenly discover the pipe connected to a combined sewer after all.

    singletrackmind
    Full Member

    I have the exact same scenario.
    At work now but will go into more detail later.
    Really, you need a great big hole, and some egg boxes to build a new , effective soak away.

    ayjaydoubleyou
    Full Member

    Can you ask for a second opinion? Subsidence in clay soil is normally vegetation related (which causes the soil to heave or shrink). What mechanism are they proposing that the water is causing the foundations to move?

    The vegetation causes movment because it draws water out of the soil. Heave/shrink is purely down to water content of the clay.

    Dumping half a roof’s worth of rainwater immediately adjacent to the house will give a similar but inverted problem.

    TBH, it’s not the right thing to do, but I’d put the down pipe into a back inlet gully and connect that to your foul drainage. It’s what happens in most houses up to about 10/15 years ago. Just don’t tell anyone….

    Practical (ignoring the illegality) advice, but I’m guessing that there is no foul at the front of the house based on the description.

    What is stopping you taking the water to the back OP? slope of the site? or mid terrace?

    peter1979
    Free Member

    I guess there is nothing stopping me from taking the front rainwater guttering and diverting it to the back. We are end terraced. The main concern is trying to satisfy the insurance company that we have followed buildings regs as I’m concerned they will be looking to get out of what they can with regards to future subsidence works (ie underpinning).

    singletrackmind
    Full Member

    My house , detached, was constructed in a similar way . 3 pipes going straight down into the footings with a few dozen smashed bricks to allow the rain water to soak basically the ground next to and under the footings.
    However, my house is tiles with red tiles that have a kind of crusty sand on them. These bits of sand fall off and fill up the voids and pipes so we had overflowing problems.
    What I did was to dig away a trench approx 4 mtrs from the base of the stack and send the water to a new gravel soak away under the driveway..
    Getting a decent fall to ensure that the red sand from the tiles didn’t settle was the hardest part. Currently I think you need a cubic meter of soak away filled with special boxes to ensure that they don’t collapse

    footflaps
    Full Member

    TBH, it’s not the right thing to do, but I’d put the down pipe into a back inlet gully and connect that to your foul drainage. It’s what happens in most houses up to about 10/15 years ago. Just don’t tell anyone….

    they do that a lot round here in the villages on clay as the ground won’t drain.

    As for the 5m rule, when I put in soakaways for the workshop, Building Control were very relaxed about it all….

    The main concern is trying to satisfy the insurance company that we have followed buildings regs as I’m concerned they will be looking to get out of what they can with regards to future subsidence works

    Easily done, discuss it with BC and then get them to sign off on it. That’s what we did. I just emailed in photos in the end, and they just approved it by return email….

    Ewan
    Free Member

    “I’m concerned they will be looking to get out of what they can with regards to future subsidence works (ie underpinning).”

    Don’t assume they will underpin. If you remove the source of the problem then there isn’t always a need to. My house had minor subsidence as a result of a hedge and a tree on the front (as ayjaydoubleyou says it was sucking the water out of the clay). All they did was use rods to stitch the bricks back together, and remove the trees / hedge, and some cosmetic work – total cost was like 3k. Changes in the water content aren’t a problem (to an extent) if the whole house is impacted, it’s largely differential movement that will cause cracks. If you partially underpin, that in itself can cause issues as then one bit of the house will move more than another, so you then get cracks at the junction.

    If you’re on heavy clay then a soakaway will never work. You’ve basically got the option of a) connect to a foul drainage as a combined drain b) connect to an existing ditch or water course c) create a sump and have a pump to pump the water elsewhere (lower than the house). If you create a soakaway on clay, all you’ve really done is create a sump anyway.

    keithb
    Full Member

    Oh, and make sure you’re not paying your water company for taking away your rainwater too. Can claim back up to 5 years of charges IIRC. Made a small but not insignifiant difference to ouw water bills when I did that. Some of our roof dischsrges via pipework onto the footway on the street too (there’s a seperate charege on water bills for highways drianage).

    our soakaway in teh back is only c1m from the property. 1890s build though, to pre-dates building regs I’d imagine…

    munrobiker
    Free Member

    The first thing to do really is test to see if the soil is permeable enough to allow water to soak away. I’ve done hundreds of soakaways tests over the years so let me know if you need someone to do it and I can point you in the right direction (I’ve left the industry now). If the soil isn’t permeable then a soakaway won’t help.

    It’s unlikely a soakaway at the front will help you given the space. If you put in a small diameter soakaway, say a metre, at the front of the house then even at its furthest it will be 2.5m from your foundations. The soakaway will then just discharge water next to the foundation if you’re draining enough water. A civil or drainage engineer could calculate likely volumes for you.

    Rich_s
    Full Member

    Soakaways and subsidence is a complex area in buildings insurance. If you’ve not already tried, then it might be worth complaining to the insurer (and then the ombudsman) about what’s gone on.

    It’s a bit different from what I deal with day to day but here’s a link to FOS about it:
    https://www.financial-ombudsman.org.uk/businesses/complaints-deal/insurance/home-buildings-insurance/damage-underground-pipes

    And if you search for FOS decisions subsidence soakaway you might find some relevant examples of decided cases.

    Just seems odd that they seem to have accepted a claim for subsidence, have apparently decided they might have discovered the cause, but then say that’s not covered. Usually subsidence cover is pretty broad. I can understand why they might want you to contribute towards costs of improving your home, but it all sounds a bit odd.

    gowerboy
    Full Member

    TBH, it’s not the right thing to do, but I’d put the down pipe into a back inlet gully and connect that to your foul drainage. It’s what happens in most houses up to about 10/15 years ago. Just don’t tell anyone…

    If you do that… please never ever complain about sewage discharges from overflows into our rivers and sea.

    peter1979
    Free Member

    Thanks for all the advice. The claim has been long and complex and it seems like it’s not really going anywhere right now.
    We are end terraced on a big hill with a large drop to the side of the property. The insurance company have done trial pits, sewer investigations and are monitoring the movement to see if it’s progressive, which it appears to be.

    However they have said that our end wall is laterally detached and isn’t covered by insurance and will need to be repaired at our cost and also the rainwater drainage will need repairing at our cost. We also have a boundary retaining wall which connects to the front of the house which appears to be about to fall into the neighbours garden, but again this isn’t covered. It’s been a real headache and I’m still waiting to find out what, if anything, is going to be covered. We have to fix the drainage first, but the cost of this is pretty high and I just don’t really know who to trust and if this is going to solve any of the issues. We’ve in the process of getting second opinions. Also, getting people to actually come and quote for work, especially when they are told about the insurance claim, has been tough.

    footflaps
    Full Member

    However they have said that our end wall is laterally detached and isn’t covered by insurance

    Are they just saying that hoping you’ll accept it or is that actually in contract?

    I’m sort of hoping a wall detaching is the sort of thing our insurance would cover, as if it doesn’t cover walls detaching / falling down, you wonder what it would actually cover….

    Rich_s
    Full Member

    Boundary walls are usually covered for subsidence when a claim for subsidence to the main building is being covered. I think it has to be the same cause.

    It does sound like your insurer is doing the right sort of thing. But obvs on here it’s all a bit short of detail.

    I’d be tempted to ask exactly why are parts of your claim being declined (in other words, what parts of the policy wording are they using to push out cover). So, why are the other walls specifically not covered. Why is the rain drain not covered. Why do you need to pay. Etc.

    Once you have all that, and if not happy, then complain and FOS. It won’t necessarily fix the problem any quicker so you still need to jump through the hoops, potentially pay for things yourself while it all goes on.

    Just out of interest, who’s the insurer? Feel free to pm or drop a subtle hint on here in rhyming slang if you don’t want to mention them.

    mugsys_m8
    Full Member

    OP, what part of the world/UK are you in? This is part of my profession as a freelance geotechnical engineer. I suspect a small geotechnical/ structural consultancy may well be the best port of call for deciding on plan of action,but also most importantly to stand with you wrt. your insurers. This is right up the street of one of my current clients, especially if you are based in the SW.

    Sounds like many things going on: structural defects to remediate, drainage measures to improve, potentially deep seated failures relating to the slope etc. It sounds like a soakaway will not work in your ground, and it could have been expected that your insurers procured ground investigation would have stated this in their conclusions…

    Feel free to contact me.

    Dan

    gray
    Full Member

    Sorry to hijack slightly, but if anyone knows someone good who could give some advice on soakaways in the Oxford area then please post here or DM me, thanks!

    fenboy
    Full Member

    similar but not the same issues we had led to an insurance claim that took a lot to fight to get the right outcome, initial kickbacks from insurers was not insured. as an architect and with good engineering friends was able to outclass their assessments and present the actual technical reason for the issues and demand a solution that worked and was the right one. I agree with mugsys_M8 get an engineering consultancy to act on your behalf and carry out your own assessment of the scenario without relying on the insurers “experts” or trade opinions.

    ossify
    Full Member

    Why waste the water? Just get a bunch of water butts and store it all for use in your garden.

    Here’s a picture of my house:

    _e909fbca-a118-4b44-a34b-22711fa27f19

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