Will removing tree roots cause damage to house?

yourbluejumper · 10-07-2022 9:22pm #1

So our new house has three absolutely massive tree stumps (3.5ft - 4.5ft wide each) in a side garden between the outer wall of the house and the outer wall of a granny flat. The house is over 100 years old and the trees were here before the buildings and I've been assured they were absolutely giant before they were cut down about two years ago. Due to the age of both buildings, neither have foundations and the roots are definitely in under both the house and the granny flat. My question is, if we get the roots completely removed, is the removal of them going to cause issues with the structure of the house/granny flat? Like if we pull out these absolutely massive roots will the void left by them cause sinkage or stress on the walls or anything? Alternatively, if we leave them where they are and let the trees grow again, will they eventually cause damage to the walls by continuing to push up the ground underneath? Currently there's no evidence of issues with the outer walls. The house is mass concrete and the granny flat is stone.

looksee · 10-07-2022 11:02pm

This is probably something that needs expert opinion by someone on site, not a random bunch of people on the internet who are not aware of all the issues. We don't know what kind of space there is between the house and the stumps for example. Or what kind of trees they are, which would give an idea of the type of roots you are up against. You are assuming that the trees will grow again, is there any indication they are still alive? The tree is not going to regrow the way it was, anyway. At most you would get some shrubby branches growing out of the stump. It seems unlikely that it is still alive. It also seems unlikely that you would be able to remove roots completely, how would you envisage going about it? Is it essential that you remove the stumps, what is your reasoning for removing them?

Generally I think (and I am not an expert) you would leave the roots where they are, this would be the least intrusive way of dealing with the situation. You could get the stumps ground down, or you might make a feature of them, it depends on what you want to do with the space.

yourbluejumper · 11-07-2022 12:00am

Thanks, I have had someone out to look at the stumps and advise on removing them but they didnt seem to have a lot of experience, said these would have been the biggest stumps they'd ever removed and weren't sure about structural ramifications. I understand I need expert advice on the matter, I'm not going to base my decision solely off people's replies here, I'm just trying to get some information from people who might have had similar situations.

I also realise the trees won't just grow up again, but there is quite a lot of new growth sprouting on them in the last few months so they are still alive.

The person we had out to advise said they would grind them down, cross cut them, fill the cross with some kind of solution to kill them, and then after a month the whole root system would just lift out of the ground.

I'm not against keeping the stumps, but the root systems are so massive that it's made the whole side garden massively uneven so it's difficult to maintain the ground around them. The roots have also cracked the concrete path they run under and generally have made all the ground around that area uneven and a hazard.

homer911 · 11-07-2022 11:10am

By any chance did you get the property surveyed before you bought it?

yourbluejumper · 11-07-2022 11:24am

Yup, had an engineer do the structural report for us, nothing to do with the walls etc was found to be an issue and I remember the report didn't mention the tree roots at all. That part of the garden was fairly overgrown at that point I think so the roots probably weren't as noticeable and I would say the engineer assumed the trees were dead, as did we.

wildwillow · 11-07-2022 11:41am

You need to get expert advice. We had a dying tree cut down from beside an old entrance wall and left the root. Two years later the wall began to crack. The dying roots had shrunk and the wall cracked as it was lowering into the space created by the roots. Tree wasn't huge and wall was low so it settled and we repaired it. I suspect your question is this scenario multiplied by a thousand.

magicbastarder · 11-07-2022 12:59pm

i have also heard of an effect where the ground can swell after a tree is chopped down; if the tree has been sucking the moisture out of the soil, the removal of the tree can allow the moisture to build up again and the ground swells. i've no idea if this is common though. given that the trees are down a couple of years, i suspect that you wouldn't have to worry about that anyway.

The Continental Op · 11-07-2022 9:32pm

https://www.boards.ie/discussion/comment/119321231#Comment_119321231

Good point, always referred to that as Willow Heave. Happens most often in heavy clay soil when large willows are cut down. Not so much of an issue on well drained loamy soils.

Edit> Google found some interesting info

https://arbtalk.co.uk/forums/topic/96348-chances-of-heave-if-willow-is-felled/

https://www.assetsure.com/homes/home-insurance/what-are-the-four-worst-trees-for-causing-subsidence/

Will removing tree roots cause damage to house?

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