Advice on milling building locust retaining wall

[lavarock64]

New to the site, already have gathered gret info.

I'm building a 100'x 6' seawall (w/ tiebacks) out of black locust on a local lake this december ( when the lake level goes down).

I'm currently logging the trees from a small woodlot and plan to have a portable mill come in. I'm starting with the trees that fell years ago and will finish with some that are still standing. Given the logs I have to work with, the bottom of the wall will have 8-10" timbers and it will taper to 5-6" at the top. I want the face of the wall to be flush. Should I have the mill cut 3 or 4 sides of the timbers? 3 would give me mor material in the wall, 4 would give me the option to rotate the timber for a possible better fit. Should we mill in beams by the inch 6,7,8 or every even inch 6,8,10?

Should I add any preservative? The specialists I've talked to said locust is so dense that not much will absorb thoughts? Should I worry about spliting/ checking?

Thanks, Lavarock

 

[BIG JAKE]

I'd think preservatives would be a no-no, as it will leach back into the lake. A rubber membrane on the inside of the wall might be worth consideration. You might check with your local regulators including fish/game dept to see if a permit will be required. That could govern what you have to do. As far as milling if you go three sides, build the wall soon after you mill for best fitment results. Welcome to the site!

 

[Sawyer Rob]

Treat them with what? There's nothing that YOU can buy "legally" that will preserve them. Home remedies don't work, even though some keep repeating what they "heard" will work.

Rob

 

[hamish]

No idea about black locust as its a species i am not familiar with, but tamarack (or larch for you southerners) loves water/moisture...just a thought.

Forgo any preservatives...........all you are doing is killing more water life.

 

[TraditionalTool]

Black Locust is incredible wood, and it's extremely hard. It is also one of the more rot resistant in the U.S., AFAIK. It is one of the most dense and hardest woods in the U.S., so I have been told.

My friend who taught me to build with logs, always speaks favorable about it.

It is used for split rail fencing and there is a place in WV that still produces split rail sections. You can split it with an ax, and what they used to do in the old days. It is also XLNT firewood if I remember...but it grows in the east, so we don't have any of it out west.

I would think it would be excellent for a retaining wall. Certainly wouldn't hurt to spray some Tim-Bor mix on the timber, or other borates. I've also heard of folks treating/spraying around the soil with borates.

 

[Birdhunter1]

One thing I will add is build the wall as soon as you can and do not let the wood cure. With my cordless DeWalt 1/2" impact wrench I snapped a 1/2" lag bolt going into a locust 4x4 with no pilot hole. Also drill a pilot hole. This was on a post that the tree had been cut 18 months prior and milled 7 months prior.

 

[lavarock64]

Thanks for the welcome and your thought guys. To answer a few questions:

1- I applied and was approved for this project through the Dept of Env. Conservation and the Army Cor. They actually moved it through quite fast, which is suprising considering the hassles others permit holders have experienced. I talked to both departments and no one has reviewed a permit using locust for a sea wall material. This project may be a natural poster child for them - who knows.

2- I talked with Bill at logfinish.com and he intern talked with product specialist / chemists about the locust. The summery was that due to the density of the wood penetrating products won't work (Borate). So the one possibility he had was a surface Sikkens log pretreatment to prevent checking / splitting that would last about a year. Any cheaper ideas than this product? Any one have experience with this stuff?

3- I've built a large dock 6 or so year's ago and the wood did move some. It actually snapped many of the deck screws as it aged. And yes, all the holes were predrilled.

4- 99% of the time only the bottom timber will be at the water level. During flood events (1%) the water will rise 1/2 way up the wall.

This is a very labor intensive project for a weekend warrior, so I just want the wall to last as long as possible (hence the preservative inquiry).

Thanks again, Chris

 

[Birdhunter1]

In addition to what i had posted earlier I recommend through bolting when using locust timbers as opposed to trying to hold them together with a screw or lag bolt.

 

[TraditionalTool]

One thing I will add is build the wall as soon as you can and do not let the wood cure. With my cordless DeWalt 1/2" impact wrench I snapped a 1/2" lag bolt going into a locust 4x4 with no pilot hole. Also drill a pilot hole. This was on a post that the tree had been cut 18 months prior and milled 7 months prior.

Those are crap, get a Hitachi and never look back. The Hitachi will rip your wrist off if your not careful. I had a POS Makita, it couldn't barely put a 3" decking screw in pine, even with a new battery...got a Hitach and it was like night and day...I haven't used the Makita since. The DeWalt ain't much better, IMO.

 

[TraditionalTool]

2- I talked with Bill at logfinish.com and he intern talked with product specialist / chemists about the locust. The summery was that due to the density of the wood penetrating products won't work (Borate). So the one possibility he had was a surface Sikkens log pretreatment to prevent checking / splitting that would last about a year. Any cheaper ideas than this product? Any one have experience with this stuff?

Personally I don't care for Sikkens products on logs/timber, because it doesn't allow the wood to breath. I don't know about the log pretreatment though, it might not seal and could be fine.

As I mentioned, some folks do spray borates around the soil area. It will kill any insects/bugs that are there. The problem is that it washes away with rain, so...this holds true for timber also, once it rains on it, it typically washes it away. For log homes they typically spray the borates and try to finish it quickly after, to retain it and seal it in the wood.

 

[Birdhunter1]

Those are crap, get a Hitachi and never look back. The Hitachi will rip your wrist off if your not careful. I had a POS Makita, it couldn't barely put a 3" decking screw in pine, even with a new battery...got a Hitach and it was like night and day...I haven't used the Makita since. The DeWalt ain't much better, IMO.

Since I have about 5 tools that are 18V cordless DeWalt it wouldn't make sense to switch, I think you may have missed something I wrote. . My impact driver has no problem putting 3" screws into Poplar, Pine or Ash or Oak, usually the screw will break before the machine runs out of guts.
However in my previous post I was referring to my 1/2" impact wrench, big difference between this tool and a driver. This one has 300 ft. lbs. and will take lug nuts off a car or truck.

 

[TraditionalTool]

Since I have about 5 tools that are 18V cordless DeWalt it wouldn't make sense to switch, I think you may have missed something I wrote. . My impact driver has no problem putting 3" screws into Poplar, Pine or Ash or Oak, usually the screw will break before the machine runs out of guts.
However in my previous post I was referring to my 1/2" impact wrench, big difference between this tool and a driver. This one has 300 ft. lbs. and will take lug nuts off a car or truck.

Bird,

Yeah, the impact driver is better, no doubt. I drive in 6"-12" lags with my Hitachi, which has a hammer mode if I need. I find the drivers more useful, but all of our mileage varies. If I was to get an impact driver, I'd get a Hitachi, as I would a circular saw. I have a Makita circular saw, but it barely lasts to cut down a full sheet of plywood.

IMO, even if you have 10 tools of the same type, if they are not up to the job, the 1 tool that does work is way better. Hitachi wins hands down for me in that regard.

 

[StevenBiars]

Have you considered using some tar? I would greatly consider coating the ends of each cut piece with tar, and the entire bottom row, and then building the wall. Once it's built and in place, I would go back and tar the entire backside of the wall and then add a gravel or sand buffer to keep water from pooling against it, then backfill the rest with whatever soil has been displaced. On the front side, I would tar everything below the water level and perhaps one timber above that level. The key is to make sure that the topmost timber to be tarred ends up getting tarred on all sides. Otherwise, you risk having a timber that's been coated on the sides and ends, but ends up drawing moisture from the top (thus rotting it out). The majority of chemicals that would be leached out of the tar are typically promptly consumed by several kinds of microbes. It's certainly a lot more friendly than pressure treated wood.

 

[Justsaws]

Having never built a wall such as you are describing I am curious as to how it is to remain up right. Are you burying x amount of the wood and then back filling over braces behind the rest?

In terms of fitting the wood, it is a race against time, the more wood you leave on the pole the more time you get. Mill what you need for fitting and leave the rest. Locust holds up well compared to other wood but still rots over time. Does your design allow for the replacement of individual pieces or sections?

I would not bother trying to treat the wood and would also recommend the use of bolts/all thread all the way through the wood instead of lags or screws.

Sounds like a neat project.

 

[1harlowr]

I'd guess the bolts or screws will rust out before the wood rots. Having a layer of locust under water almost 100% of the time though might be tough on even locust

 

[lavarock64]

Again, thanks for your thoughts. I've been chipping away in the woods and have about half of the logs out. Having a real problem with the locust splitting when I'm felling the trees (still perfecting my plung cut).

For more clarification, the current rotted wall is made out of railroad ties/ My guess is it's been there for 60 or so year's. Regulations don't allow for a wall greater than 12' in thickness to be installed (lake encroachment / habitat loss).

The prior owner had a backhoe and drove in heavy 4 inch steel pipes about 12 inches from the existing wall and cobbed together a his form of gabian (stone) baskets / fence. I removed that mess and plan to install the new wall against those pipes. I will dig into the beach gravel about 18 inches for the base. For additional unity I will bolt the bottom timber to the pipe. Then the plan is to use a mixture of railroad spikes and 1/2 rebar to tie the timbers together. Ideally it would be great to line up the predrilled holes and drive a 4' piece of rebar through the whole wall. This iron will be about every 2 feet. I will rent a machine to dig holes for tie backs that will go through the existing wall.

I like the idea of the tar. I did not spec that on the plans, not sure how the regulators would think of this material? The backside of the wall will be backfilled with beach gravel.

I'll try and get pix of this mess up at some point.

Thanks, Chris

 

[Sawyer Rob]

I wouldn't use tar, i've seen it used on poles for pole buildings, in the end it trapped water against the wood and the wood rotted even faster. The wood will keep moving, and many times the tar comes away from the wood and it just holds in the water/moisture.

Rob

 

[tomtrees58]

locust will not rot it will last over 100 years its used in house beams here and sea walls you can put a tin cap on them but i would leave it tom

 

[lavarock64]

Good point....... I've pulled several locust fence posts over the hears that were likely 60-80 year's old that were still in usable condition. Given that I'm back filling with beach gravel, the only area that will be in the water is the bottom timber.

Any suggestions on an insect control? It sounds like Borate will wash off....... Some of the trees I'm cutting are loaded with big black ants (carpenter?)

 

[tomtrees58]

Good point....... I've pulled several locust fence posts over the hears that were likely 60-80 year's old that were still in usable condition. Given that I'm back filling with beach gravel, the only area that will be in the water is the bottom timber.

Any suggestions on an insect control? It sounds like Borate will wash off....... Some of the trees I'm cutting are loaded with big black ants (carpenter?)

is it in salt water or fresh no ants wen that is cut it turns in to rock