Norvegian maple trees

[65hoss]

Hi,

We have two Norvegian maple trees here and are concerned about the possibility that they eventually damage the house foundations.

They are 35 and 38-year old, the youngest being 2.5' in diameter while the oldest is 3' in diameter. I had difficulty measuring the height (could not back off far enough) but they are at least 40' high.

Their branches cover a radius of around 26', which means that there are branches over the house for about 8'. Note that these were cut in the past, so they would probably be longer if they had not been cut.

Are they at risk to cause damages to the house foundations?

If so, are there any measures that can be taken to prevent this and not have to remove them?

Thanks,

Pierre-Luc

 

[M.D. Vaden]

Our experience, is that slab type concrete foundations as in some houses, and many garages, get damaged easier that the perimeter foundations that are "formed" (having maybe 24" or more of vertical dimension).

On my own lot, I'd feel comfortable with the trunk of a tree like that 15' or more from a "formed" foundation.

If I had a slab, then 20'.

If the roots had not made it to the foundation yet, I'd go to a nursery or arborist supply and buy the root barrier sheets and lay them in a trench. Then I'd feel very comfortable even if the tree was 10' away.

 

[65hoss]

Thanks for the answer. We have yet to check if the roots have reached the foundations, but will probably do so in the next few days.

To protect foundations, I assume that 48" deep root barriers would be the best bet? Also, is there any risk that they are moved due to cold temperatures here (zone 5)?

Thanks,

Pierre-Luc

 

[M.D. Vaden]

I recall the barriers being more like 30".

Usually the design of a product like that conforms with the need.

If roots got under 30", it would not be within your lifetime that they would do damage.

 

[John Paul Sanborn]

40 ft sounds consistant with the DBH

If you look at how a root grows, it cannot cause structural problems if that structure is designed and built properly. a root against a rock will deform from the optimal cylidrical form, not push it out of the way.

Tree growth is by adding a small layer oc cells on to the old, cells are water filled sacks, not hydraulic jacks.

Also, roots will grow where there is sufficient O2 and H2O, oftem we will dig under a houses eaves and find no rooting due to lack of water. A solid slab with tamped soil will not have sufficient for good root activity.

Another component is waht was used for backfill. They are finding that cost cutting contractors have used spoil dirt that is high in dynamic clays for backfill vs. gravel or sandy soil. Dysnamic clays expand and contract with hydration/dehydration cylles mor then any other soil, so much so that foundations and basement walls can heave. I've seen old soaker hose labels that recomend their use for keeping foundation soils moist to reduce the cahnce of this heaving.

The bottom line isthat trees often get blaned for the shoddy workmanship on buildings and hardscpaes. People tell their freinds that the trees wrecked their basement so they tell otheres tand everyone is scared that the tree will wreck thier home, so they cut it down and the utility bills go up.

 

[geofore]

hyddraulic jack

I thought the roots can and do exert 150 lbs per square inch, like a hydraulic jack I'd think. I'll agree trees get blamed for a lot of things they don't do. I mean like the cheery tree that got blamed for getting George Washington in trouble when it was the Hickory tree handle on the axe that was to blame for the cherry trees demise.

 

[65hoss]

Thanks for your answers.

JPS: I forgot to mention, but the soil in our region is mostly clay (pretty good for agriculture, but not necessarily for structures), and the backfill seems to contain a lot of clay as well. If I dig 1' in the soil I can see almost only clay, so I guess the roots must not go very deep?

Would root barriers installed about 1' from the house help protect the foundations from structural denivellation and the such since the threes would not pump water in the soil directly next to the house?

Also, I found small roots (the biggest being about 1/6" in diameter) near the house, can these be pruned with no problem or would it have a negative effect on the threes?

Thanks!

Pierre-Luc

 

[M.D. Vaden]

Even if the roots were bigger that 1/6", if they did cause a problem, they would have to be cut anyway.

It wouldn't bother me. Even moles do worse. Those roots are barely bigger than the roots that are routinely root pruned on Bonsai trees, and those last for centuries in little pots.

As far as properly built structures, those would have to exceed code by leaps and bounds in many cases for slab foundation - especially garage to see no damage.

Trees can damage code slabs in many cases.

I beg to differ on the properly built house concept.

A properly built house is not one that resists any potential tree damage, but that usually meets code and then some.

But big trees have enormous, enormous ability to heave concrete and walls. Especially in heavier Oregon soils.

Location is one factor. I still stand by my original post concept.

Its not even worth my time to post pictures on here of houses in our area that are being lifted by more vigorous trees.

A proper foundation will crack. If it does, either too big of a tree was too close, or, no barrier was put in to divert the roots.

Remember, if you try to think like the 100% arborist, you may go crazy. Don't let the trees run your life. Rules are fun to bend. Life without flexibility is a dissappointment.

 

[John Paul Sanborn]

There have been several studies conducted with hardscape showing that properly engeneered structuress can survive tree roots.

Other studies I have read show taht most damage done to foundations are from dynamic clays heaving. if proper balast and backfill were used, thes things would not occure.

I'll stand by my position too. It takes around 8% O2 in the soil for roots to be able to grow, so if the foundation is poorly constructed so that airation occures, then roots can colonize under the slab. Heaving of the soil allows the roots to grow, then they eventual get balmed for the problem that allowed them to be there.

 

[65hoss]

Thanks a lot for the answers.

Now, assuming that the soil here is mostly clay (and that is not only the backfill, but the soil in general), how deep would the roots go approx? I dug 1' deep and did not see roots for 4" but am wondering if there can be some big ones depper than that?

Also, would the root wall help preserve the moist in the soil near the foundations or would the effect be negligeable?

Thanks again,

Pierre-Luc

 

[M.D. Vaden]

What's interesting in Oregon - the houses on the clay soil rarely have no problems from heaving all the first years.

Then, the following years, when the big tree roots grow under foundations of slab foundations and single story foundations, the foundations crack.

An interesting point of view of the general public - they don't have much exposure to studies of the theoretical or ideal housing foundations. Most homeowners are dealing with what they see, and the current surroundings.

More than 1/2 of the builders, will not exceed minimum standards. And more than 1/2 of the landscapers will plant trees close to houses and garages.

It will be a rare day in Oregon that builders do Oxygen tests on soil for houses. Its a bit more extensive for commercial work, but residential is a matter of scrape away, lay gravel and forms, then pour the concrete.

The number of untouched mole tunnels in the soils here also allows for a large amount of exchange of water and gases in the soils - a natural aeration.

I saw a beauty of a root today. Its from a poplar. There's no way its going to lift the foundation of a 3 story dwelling. But its starting to heave the soil near the gas meter.

plsoucy - about the moisture - how close to the foundation would the barrier go?

Whether the rain fell behind it or not may matter a little.

 

[John Paul Sanborn]

Root bariers are mostly plastic impregnated wioth copper compounds.

These barrieres will not effect the soiul moisture, wind direction and the depth of your eaves will do that.

 

[65hoss]

JPS: assuming that the barriers prevent the roots from going near the foundations, they will also prevent the trees from taking water there, no?

MD Vaden: I was thinking at something like 2' to 4', woudl that make sense? I sure do not want them to be in the middle of the grass, where people could fall on them, but can probably put them 4' from the house and put some flowers between the barriers and the house so people do not walk on the barriers anyway.

Thanks,

PL

 

[John Paul Sanborn]

PL, yes, since the tree will not be "feeding" in that area, they will not effect the hydration of the soil.

As for instalaltion distacne, I would say as far as you can go awayfrom the tree and still be happy.

If you have a walkwaypast the eves of the hous, but it on the edge of the walkway.

Here are some research papers on roots and hardscape.

http://joa.isa-arbor.com/search.asp

Well actualy they wont let me post directly to the seach results, so just enter sidewalks and do the search.

 

[M.D. Vaden]

If you want some flower garden bed around the house, it could be good to place the barrier back.

Once tree roots infest soil, its a pain to work with smaller plants.

The barriers are totally submerged. So nobody should trip on it regardless of where you put it.

What the arborists use from TREE TOOLS here, is thin and in a roll.

Dig a narrow trench, lay the stuff on edge against the trench wall and backfill.

People most often think of barriers to stop concrete damage.

I will be using it much more often to preserve gardening areas that are free from "reams" of fibrous roots.

In our yard, just one 25 year old Norway Maple, by way of root mass, has made an area of about 40' in diameter, a real pain for planting shrubs and flowers.

The tree was removed due to disease, but its amazing what I'm still dealing with each time I need to plant.

Now, having installed some Norwegian Sunset Maples, and a Tri-Color Beech, I will be putting barriers in several locations to protect sidewalks and planting areas.

 

[John Paul Sanborn]

Originally posted by M.D. Vaden
The tree was removed due to disease, but its amazing what I'm still dealing with each time I need to plant.

Sounds like a need for a stumpre to dig the hole

 

[M.D. Vaden]

Yes Paul, definitely a hole.

In fact, the mound that the tree heaved up, with surrounding root mass... well...

Did you see those video clips of the hole that the bomb left in Iraq? One of the last attempts on erasing Saddam?

That looks like the kind of hole that would make me a happy garden person.

The tree was planted on level ground in 1976. Now, there is a raised mounded area about 10' in diameter, and its about 24" higher than grade where the stump was cut flush with the soil in the center.

I'll make sure the guy I hire has a big machine. Realistically, it should be worth $500 to $1000 to do the area in a worthwhile manner.

 

[John Paul Sanborn]

Check with the Vermeer dealer, they will rent those big tracked jobs for around 600 I think.