Roots, Shoots, Foundations.

[Pelorus]

Was listening to part of a radio (CBC) gardening show phone-in today.
A caller mentioned he had a Kentucky Coffee tree close to his house, and recently his foundation had cracked in several places. He hired an engineer to investigate, who told him the tree roots were the cause of the problem. He then had an arborist (was not stated if the moniker was self-accredited or otherwise) tell him that pruning the limbs back several feet would "cause the roots to retract" or something like that.

The radio show X-pert's name (Drysdale?) eludes me, but he is or used to be employed with the Niagara Parks Commission) said hmmmmmmmmmmmmm, will look into this and make some calls and next week will provide an answer on the next episode of the radio show.

I know that there is a balance between the above ground and underground parts of a tree, and harming the one can affect the other. But (without actually seeing the house / tree) is pruning something that sounds like practical (or intelligent) advice? The guy loves his tree, doesn't want to have it removed.

 

[beastmaster]

I think tree roots get blamed for a lot of stuff their not responsible for. Cracking foundations is one of them. With the exception of a tree being really close to the foundation and it slowly growing up against it getting wider as it grows, Roots don't want to be under no foundation were there is no air or water and compacted ground. Often times I have seen footings act as root-barriers. Now if the slab gets a crack in it from another cause, then a root may follow it and do damage as it gits larger and larger, and end up taking the blame for faulty workmenship.
Root die back is possible if a lot of tree mass is removed, like in topped trees. How much depends a lot on the species. I am no expert but to say by trimming the tree back a few feet will cure the root problem under the foundation seem a little irresponsible.
Depending how close to the house's foundation the tree is and the size of the roots(I would bet they're not as big as everyone thinks)root pruning and bio barriers could help so long as the tree's stability isn't compromised.
I would be interested in what the out come of that claim is.

 

[imagineero]

I work in residential, so most of the trees I work on are close to buildings, drives, sidewalks etc. I do see a lot of damage from tree roots, whether you want to say it's bad concrete or whatever, they still interact. There are plenty of trees planted where they shouldn't be which later grow to be a big problem. We don't have so many problems with our native euc's, but do get a lot of structural damage caused by camphor laurels and liquidambars. Some of these monsters can send trace roots well over 10 times their canopy spread. It's not unheard of for roots to cross roads, or end up under houses 3 doors down. When planted within 10' of a house, you can imagine the damage they cause.

I get asked to prune roots all the time, but I never do. It's just too much of a liability for me to take on, and my insurance wouldn't cover me for something like that. People go hacking away with axes and saws at major primary roots, I've seen roots up to 2' in diameter hacked to install driveways or patios. What do people think is holding up the tree? Root pruning on small ornamentals is one thing, when you're talking large trees it's something else. The tree needs those roots.

Shaun

 

[treeseer]

I get asked to prune roots all the time, but I never do. It's just too much of a liability for me to take on, and my insurance wouldn't cover me for something like that.

cmon shaun you can take charge of the tree. my insurance is fine with root pruning, and branch pruning, and any other tree work. your alibi has a whiff of bs to be honest. :taped:

http://www.tcia.org/sites/tcia.org/files/A300Part8-Drft2-V1-Roots-PubRev-07'2012.pdf

is the draft version of the US root standard. Does it help define how to go about the obvious and reasonable task of pruning roots?

 

[Pelorus]

By way of clarification:
1.The name of the fellow who hosts the CBC gardening phone in show is Ed Lawrence.
2. From what was mentioned yesterday, it appears the engineer felt the cause of the cracks was not from diect root / foundation contact, but rather the roots drawing moisture out of the clay soil, causing it to settle. Something to do with a set of steps leading to the basement that are attached to the foundation. (Sounds like inadequate compaction to me, and nothing to do with the tree)

A lot of unknowns in this situation, but I thought it was odd for an arborist to recommend pruning as a way to prevent further foundation damage.

 

[ATH]

By way of clarification:....it appears the engineer felt the cause of the cracks was not from diect root / foundation contact, but rather the roots drawing moisture out of the clay soil, causing it to settle.....

So there has never been a drought that has caused the soil to dry out???

To the original question: I don't think that a good pruning job is going to have significant enough impact on the roots - especially to accomplish reduction in tree water uptake. If that is the concern, a nice watering every week is probably a pretty cheap solution.

Like you said a lot of unknows...both what we know about the situation and apparently on the part of the "experts" on the call in show as well.

 

[imagineero]

cmon shaun you can take charge of the tree. my insurance is fine with root pruning, and branch pruning, and any other tree work. your alibi has a whiff of bs to be honest. :taped:

http://www.tcia.org/sites/tcia.org/files/A300Part8-Drft2-V1-Roots-PubRev-07'2012.pdf

is the draft version of the US root standard. Does it help define how to go about the obvious and reasonable task of pruning roots?

My policy doesn't cover me for anything that goes on under the ground, including stump grinding, or even (strangely enough!) digging a hole to plant a tree. All those things are classed as excavation which needs a separate policy which is pricey due to the high cost of repair complex modern underground services like optical fibres as well as the usual water, gas and electricity.

The real problem for me though, is that I don't think we have a comparable standard in australia, which leaves me pretty much open. We have AS4373 pruning of amenity trees which sets out reasonable guidelines for pruning work, and local councils also have limits on that type of work. Those guildelines are your defence if you do the right thing and something later goes wrong. I haven't yet seen any guidelines on root pruning in australia.

Beyone that, I dont have any training on what would be good root pruning practice, so any work I might do would really be just pain seat of the pants type stuff, or more realistically just a stab in the dark. It isn't covered in our arboriculture courses... or at least not the ones I have done. I think it might be an elective subject at some colleges.

Shaun