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Slab Foundation and Tree Roots?

Discussion in 'off topic' started by Tenson, Apr 4, 2015.

  1. Tenson

    Tenson Trade: AudioSmile

    My brother and his wife are going to build a sauna in their back garden in Cambridge. However there are some Sycamore trees there. Two contractors say the roots need totally removing and one says they can leave the roots in so long as they are dead (I presume they will poison them somehow). The sauna will have a Slab foundation.

    Can anyone say who is correct? Obviously total removal of the roots will cost a fair amount of money.
  2. MikeMA

    MikeMA pfm Member

    Risk analysis is your answer.
  3. Bob McC

    Bob McC Living the life of Riley

    Get rid.
    You won't stop them with slabs if they decide to grow
  4. Mullardman

    Mullardman Moderately extreme...

    All Sycamore Trees should be killed.

    They are not native to the UK.

    Their leaves are ugly and more often than not affected with a 'sooty' fungus.

    Most of all though.. just look at the woodland floor under Sycamores. It is barren and sterile. Might be a bit of grass, but bugger all else.
    Compare this to the floor in a traditional Oak/Beech wood, which will have a good 'compost' plus interesting flowers and fungi.
    Even the typical Birch Scrub which precedes colonisation by Oak and Beech is preferable to Sycamore.
    Sycamore is a 'weed tree'.

    Kill it.


    P.S. I am openly treeist,. And proud of it.
    misterdog and naimplayer like this.
  5. Tenson

    Tenson Trade: AudioSmile

    The trees will be killed. The question is whether or not it is a high risk to leave the roots after killing. I suppose it depends how confident you are that they are dead? If the roots are definitely dead are there any potential problems building on top?
  6. Tenson

    Tenson Trade: AudioSmile

    How does one do that?
  7. hifinutt

    hifinutt hifinutt

    and of course dead tree roots will gradually degrade and be eaten by the insects potentially leaving a void . may take years though
  8. thebiglebowski

    thebiglebowski pfm Member

    Years ago my dad decided to get rid of 3x apple trees, a plum tree and a f'ing huge willow tree in their garden. The willow was about 40 ft high when he killed it and poisoned the roots. He then built a large greenhouse where the willow used to be with a 6 inch concrete foundation but in the 25 years since nothing has shifted.
  9. oldie

    oldie pfm Member

    Sycamore trees are considered a weed and you don't even need permission to fell them in the south (Brighton area). But they do tend to shoot from the base after they have been cut down unless you can remove /grind the stump.

    Soooooooo here is what you do,

    Cut down as near to the ground as you can, depending on it's size, if you are using a chain saw make sure the chain does not touch the soil/stones. and you are using all the correct protective equipment. When the tree has been felled, drill a series of half inch holes all around the stump just between the wood and the bark ,cant remember the technical name but its the fiber area were all of the sap rises,( cambium just Googled it) to a depth of about six inches or so then buy some of this.


    ( This stuff is agricultural strength ) it does come with several commercial names Clinic ace, Rosate, Gallup but it's all the same stuff, ignore all the warnings that this is not for domestic use, but wear plastic type gloves and eye protection, and wash splashed skin.

    Do not buy it from your local garden centre as it's diluted beyond recognition and will not do the job .
    Pour the undiluted Glyphosate into all of the holes filled to the top and cover the stump with a plastic bag to stop the rain getting at it. Leave for as long as you can, at least 3 months after this there will be no further growth from the stump.

    Done it ,got the tee shirt, and the video.
  10. auric

    auric pfm Member

  11. avole

    avole The wise never post on Internet forums

    Remove the roots.
  12. nirvanah

    nirvanah pfm Member

    I recently cut down a tree that was just starting to lift a concrete slab in the back garden, the tree was quite mature and I had the stump ground down and poisoned. What happened over the next 2 months was quite amazing. The root system went berserk, it was as though it was trying to climb out of the ground and proceeded to tear the slab apart. I have also repaired many a large stone wall damaged by growing roots. If it was me I'd get them out one in case they grew and the other in case they rotted and left a void.
  13. MikeMA

    MikeMA pfm Member

    How big are the trees and how extensive is the root system? What is the soil type and will it be subject to shrinkage or heave when the trees, and possibly the roots, are removed? What type of structure will the sauna be, and how are the foundations and floor slab to be constructed?

    If the sauna is little more than a glorified garden shed sat on a simple concrete slab then you might take the risk and leave the tree roots in place. On the other hand if it is a to be a larger brick built structure you might want to excavate the roots and build a reinforced concrete raft on piled foundations.

    Obviously the safest thing to do is excavate the roots.
  14. sq225917

    sq225917 Bit of this, bit of that

    Jadisman, there's a time to poison roots and that's not when the sap is rising, it's a few weeks before the leaves would fall off.
  15. oldie

    oldie pfm Member

    Glyphosate is a systemic weed killer and is absorbed into the plants /trees independent of whether the sap is rising or not.

    The one I have suggested is used in Agriculture in a diluted form to clear fields before planting, I used to get mine from a Farmer Friend who used it to kill everything from elder trees to couch grass. Applied the way I have suggested will kill all of the living tissue. As for removing the roots as a general idea have a look at the trees canopy and then imagine it upside down, that's "approximately" what the root structure will be, not a easy job to remove, that's why generally commercially "they" grind down the stump as far as they can reach with their machine, and leave the major roots.
  16. Tenson

    Tenson Trade: AudioSmile

    Thanks for all your information.

    Provided the roots don't grow, is there little risk from them rotting and leaving a void under the foundation?
  17. oldie

    oldie pfm Member

    Everything will eventually rot, including the concrete foundation, it's just the time scale that's involved. A correctly laid out reinforced raft with side walls forming a platform( upside down tray) should not be a problem . if you Google it you will find that there are several English Cathedrals that the Normans built on a raft of timber. York, Winchester and Salisbury spring to mind, Ely was actually built on a marsh and they are still standing. I doubt very much if your Brother intends his sauna to last that long. : )

    To my knowledge 40 years ago our first house was one of several hundred built on marshy ground that was "sort of drained" and all of the foundations were constructed as a sort of upside down tray( admittedly they do not use this type of foundation now preferring piling, but we drove past them last week whilst we were up at Rugby and they are still till standing and looking good.

    Rasher will be back from his Holidays next week and will be able to give you the definitive answer.
  18. hifinutt

    hifinutt hifinutt

    yes we used to live on a big raft of concrete on a ex rubbish tip with no problems . it was in prime surrey stockbroker belt too !!!
  19. Fudgemaster

    Fudgemaster pfm Member

    Tenson, you might consider getting a tree surgeon round to remove the tree above ground, as it can be quite dangerous cutting large branches, as they're very heavy. They'll also remove all the leaves/branches, and then you can follow oldie's advice to kill the roots.
    Unless, of course, you have a large chainsaw and you're skilled in chainsaw use, have all the protective equipment, and ropes to control lowering branches, and skilled assistance, plus a large vehicle to remove the spoil, in which case, off you go, and all the best.
  20. andrewhockley

    andrewhockley pfm Member

    No one has so far given the correct answer: Professional advice is required. Sorry. Depends on ground, tree, roots v house location etc etc. Not worth messing around with guesses, you need someone with insurance to write down what to do. My groundworker says use block and beam instead, but you really need to talk to someone you can sue if they get it wrong.

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