Root killer at hole in slab

[SecondAttempt]

I'm not sure if I mentioned I'm having some renovations done. I think at this point they qualify as major. I'm projecting about $60,000 on about a $1,000,000 house.

My question tonight is about a detail. Yesterday I had a plumber here to prepare the shower drain for the tile installer. I have no issues with their work but they had to chip all the way through the house slab (6+ inches thick) to move the shower drain horizontally (my request). They ran into a lot of roots beneath the slab which is not actually surprising. Most are 1/4 inch or smaller.

Does anyone know of a product or chemical I can put in the space to kill or deter the roots? With a 6inch slab above them they were no problem. I'm concerned that with just a shower pan above they might eventually try to grow into the shower. My first thought is rock salt but that would likely eventually dissolve.

Thoughts?

 

[JoeWras]

If the roots are near the perimeter of the foundation, these may be roots "scouting" for new horizons. In that case, dichlobenil, copper sulfate or plain old salt may do the trick. Look them up. It may also kill the plant.

If the roots are away from the perimeter and nearer the center, I'd be concerned about your overall drainage of the home, or potential plumbing leaks.

 

[HawkeyeNFO]

Copper Sulfate will kill the roots. Check your hardware store.

 

[pacergal]

/to kill the roots, don't you need to cut the root and place the solution on the root ends or can you simply put it around the area?
Asking because we have several roots in our yard we are trying to kill.

 

[JoeWras]

/to kill the roots, don't you need to cut the root and place the solution on the root ends or can you simply put it around the area?
Asking because we have several roots in our yard we are trying to kill.

It is always best to slice, dice, peel, cut or irritate. But you don't have to.

Remember, though, you are killing part of the plant. This is not a safe procedure for the plant.

My big old willow oak tree suffered over a span of decades after it started lifting our driveway. The driveway broke, then the sharp pieces moved over the root every time we drove. This made the root grow thicker and cause a self perpetuating loop. I eventually cut some of it out, then the tree really showed stress.

 

[Affinity4Investing]

To mitigate the root issue as well as restore some support for the drain/tile, why not just have concrete put back to replace what was removed? I'd be more concerned with restoring 'structure' for what was removed than I would be - for the tree roots. If I was just concerned with the tree roots, salt pellets laid heavily are not a bad idea but I'd probably go with 100% Roundup directly applied if possible for very small roots - or go nuclear with a product that has never failed me, called Brushtox: https://www.homedepot.com/p/Brushtox-32-oz-Brush-Killer-with-Triclopyr-75260/206737316

 

[Affinity4Investing]

Some less than nuclear options (some without harsh chemicals): https://www.weekand.com/home-garden/article/kill-tree-root-system-yard-18018195.php

 

[SecondAttempt]

Thanks for the helpful replies. The roots are near the perimeter and the hole they cut is not big enough to be structurally significant. It looks like Brushtox is not available in Hawaii. I think I will end up using a combination of copper sulfate, rock salt, and a layer of of concrete under the drain line.

I don't like Roundup, just a personal preference.

ETA: Aside from my dislike of Roundup, the roots are almost certain from the palm trees just outside the perimeter. I really don't want to kill them. I'm pretty sure they are very tolerant of salty soil systemically. The roots though would die because the salt will draw moisture out of them by osmosis.

 

[JoeWras]

Sounds like your best bet is salt. Glad to hear it is perimeter. That's good.

 

[Sunset]

Salt can be pretty tough on concrete, if there are rebars in the concrete.
The salt promotes the rusting of the rebar which then splits/spalls/cracks the concrete.

If there is no rebar then no issues.

 

[Al in Ohio]

For gosh sakes don’t use salt. Super bad for both the concrete nearby and terrible for the soil environment as it leaches down. Just google “Rootex”.