Roots

gjones

I need to cut some roots to my 50ft oak tree. The roots are about 16ft from the base of the tree. I'm putting in a brick patio. Is this OK to do or will i harm the tree? btw....im in Tyler, Texas. Thanks

osb_mail

Yes it will harm the tree will it kill it, I am not sure . I would say you are going to be getting into some major roots that close .

Ekka

I would say if you prepared prior to the cut and done some TLC for the roots that wont be cut you'd be fine. At 16' away you wont be encountering too many structural support roots (ones over say 1" dia).

What is the dia of the tree? There's some rules of thumb like whatever the dia is then 10x that as a radius is what is termed the critical root zone (CRZ).

For example, the oak is 0.5m dia then the CRZ would be 5m, which in your case is close to 15' and you'll be cutting 16' away so all is OK.

Now if your oak is 1m dia then the CRZ is 10m and you are within that. However, a loss of up to 1/3 can be sustained provided you prepare and care. The loss has to be on the outer side of the 10m zone which you are.

It is recommended you cut the roots not tear them away with an excavator or bobcat. There's machines similar to a concrete saw that will cut a fine straight line.

Once cut it would be wise to insert a root barrier or plastic sheet. That's to prevent roots absorbing too much of that lovelly concrete water and builders slush ... it will also prevent the roots growing under your slab.

The remainder needs to be cared for, you know, mulch, water, seaweed extract, charlie carp, molasses, a little organic fertilizer but no chemical fertilizer especially NITROGEN (N)! You do not want to spur growth on the tree.

Now the timing of this is important, the root cut would be best done during dormancy, however the preparation prior to the cut for the CRZ needs to be done before hand, the tree needs to store up on those goodies before dormancy so when spring comes around next it has a full swag of goodies to go about it's business including growing new roots and sealing some of those cut ones.

Hope that helps, normally you'd pay around $150 for that advice.

There may be variances on the figures for different species of trees however the concept remains universal. Some trees can take a lot of root abuse, some little.

Also depends on the terrain, are the remaining roots in rock, soil, up hill or down hill etc all makes an impact. Other arborists on here may be able to get more specific advice from experience but at the end of the day you can only do your best. I would say at 16' away for a 50' oak (juvenile) correctly done, no worries.

Attached Images

CRZ.JPG (30.8 KB, 69 views)

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Sean Freeman

Ekka's right thats the standard that we work to, one foot of radius for every inch in diameter at breast height, with some adaptations for age, health and vitality here's a local council formula from Oz with those adaptations included (BTW UK Arborists will recognise this table as being plucked from their standard!)
Table.doc

What I would recommend is that if you're going to severe roots then yes do as Ekka suggests but go beyond the radius calculated for the critical root protection zone, as the fine feeder roots are present much further out and will greatly benefit from the TLC you could give them in other words to steal Ekkas diagram treat as much of the green areas (both drk and light) as you can...your tree will thank you for it.

Attached Images

CRZ.JPG (21.3 KB, 66 views)

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Sean

Trees are poems that earth writes upon the sky,
We fell them down and turn them into paper,
That we may record our emptiness.
- Kahlil Gibran

Ekka

Here's an example of what I mean, this is poor encroachment and not from the outside. One must factor the possibility of all roots lost to the right of the drive way.

Attached Images

CRZ2.JPG (31.9 KB, 64 views)

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gjones

I appreciate your responses. The Oak is not Juvenile, I'd venture to guess that it is at least 50-75 years old. The two roots that i need to cut i think are pretty major roots, i have not dug around to see exactly how large they are but they are somewhat on the surface and seem to be pretty thick. (thick enough that they have taken lawn mower abuse of the years). The patio i want to put in is right next to the house, so there wont be anything covering other roots that are not already covered by the house. I don't plan on cutting any roots other than the 2 that are on the surface so that i can level the ground for the patio. The patio is only going to be "bricks" laid down on the surface of the soil leveled at about 3" below the surface.

Sean Freeman

Well the same rules of limiting impacts apply that have previously been stated to try to ensure the longevity of your tree. However the laying of brick or concrete pavers over any living root system I'm afraid is asking for trouble down the line. Your pavers will end up being lifted by the tree roots unless you remove absolutely all of them under the proposed paving and install a good quality root barrier along the edge of your pavers to prevent root growth under them. In doing that you are going to remove more root mass, installing pavers this close to even an early mature tree is asking for trouble really.
On the other hand if you are looking at the pavers as a somewhat temporary structure then I suppose the fact that the tree will lift them creating trip hazards is not such a bad thing.....but if the pavers are to be a bigger longer term project, major landscaping then I would advise considering changing o a suspended timber deck much less impact on the roots and soil (when carefully designed)

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Sean

Trees are poems that earth writes upon the sky,
We fell them down and turn them into paper,
That we may record our emptiness.
- Kahlil Gibran

Ekka

A tree friendlier alternative would be to put in posts and bearers, have a raised timber deck.

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mdvaden

If they were a few 3 to 4 inch roots, I wouldn't worry too much. 6" roots - maybe I'd be getting concerned.

Sure you don't want a deck that can bridge the roots?

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gjones

I think from what I have learned here that a deck is the better option. The tree shades most of the house for the early part of the day and it's hot here in August. I dont want to kill the tree. Thanks for all the help