"daylighting" - excavation around tree roots by water?

[Chip C]

I would welcome any comments and advice on the technique known as "daylighting" in which soil near a tree is excavated using, as it has been explained to me, pressurized water and suction.

My basement needs waterproofing but an arborist has recommended that we not cut the roots of a large old nearby oak tree, which rules out hand excavating. My contractor is now proposing this "daylighting" techique, to be done by a specialist.

I'd appreciate any hints as to what questions I should be asking.

Thanks,

Chip C Toronto

[Joseph Meehan]

I have never heard of it, but it does make some sense.

Now for the down side. If you have a large tree that close to your foundation that it would need that kind of treatment, I suspect that it is too close to your foundation. large trees that close to your home can cause a number of problems, including maybe the one you are trying to solve.

I know, I have one too close to my home also and some day I am going to regret that I have not removed it.

[m Ransley]

how close is the tree

[Jagoff Jameson]

How empty is your head?

[Joseph Meehan]

My tree is a pine about five foot away. I have no idea about Chip's tree, but his oak appears to be close enough that there are enough roots close enough to the foundation to cause some worry about the health of the tree while excavating for waterproofing the basement wall. I would say that is close enough to be concerned about damage the tree may do to the home.

[m Ransley]

5 ft is close, the county arborist I had out said cutting 15ft from an old oak would stress it and give it a 25% chance of dying in 4 yrs. I was wondering if he really was in a risky area to cut

[DanG]

I don't know what type of Quercus you have, but if you have a foundation within 15 feet of a major oak, you're too close.

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Keep the whole world singing. . . . DanG

15ft from

[Chip C]

Ah, now that's an interesting factoid...my foundation is also less than 6ft from the tree. Yes, that's way too close, but the house has been here for over 90 years and the tree (per an arborist's guess) maybe 60 years longer. And yes, some of the foundation problem (bowing inward) is caused by the tree; I suspect that the whole volume of space outside the foundation is just a tangle of big roots.

But that's the situation I'm in, so the question is whether this water-squirting trick is likely to work, or cause more problems than it will solve. Maybe it's too new for folks to have much experience with it...

Chip C

[Jim Elbrecht]

-snip-

Can't help with the daylighting-- but if it were my house & I had a

60yr old oak 6 feet from my house I'd be thinking about removing it anyway.

Ask a local arborist for some pictures of trees he's removed from houses after high winds, lightning, or ice storms. It isn't pretty. Oaks are pretty susceptible to all 3 of those threats.

At best the fix for the roots will be temporary. Remove the tree & plant a new one further from the house. You get to pick the tree & place it where you'll get the most benefit.

Jim

[Chip C]

hmmm...your point is well taken, but the tree was 60 yrs old when the house was built, 90 years ago! Removing a mature oak around here gets your name in the papers. Oh, one more thing: it's not my tree, it's on the neighbour's property! Bottom line: the tree ain't moving.

Chip C

[Jim Elbrecht]

-snip-

My bad-- so 150 yrs. I still feel the same.

It's got a few more years to go before it's *really* mature-- It was just a pup during the War Between the States.

That sure complicates things-- but I still think you're choosing between a tree & your house. [not to mention the people in it] Make sure your neighbor keeps his liability insurance up to date.

Jim

[m Ransley]

My info on cutting 15 ft to the tree was based on my house in that I would have been cutting all its old roots. Cutting 2 feet into roots is different . But I imagine they are pushing your foundation and will grow back, whether it will damage it I dont know.

[David Efflandt]

Squirting water to remove soil is as old as the hills. Back in the gold rush days they literally hosed down mountains to get the gold out (I saw the piles of washed out rubble in California).

But you are likely to find roots as big as a tree pushing at your foundation. And if the tree is anchored to your home, is it going to topple over if you wash out one side of it or cut some roots away? It may also need some branch pruning, to keep it balanced or compensate for root reduction. Good luck. Whoever originally let an oak tree grow there was ignorant.