Using Black Locust as an exposed building material

Alright, I realize this question isn't necessarily about building a super energy efficient house.

I was wanting to build a deck onto my existing house, but for several reasons I don't really want to use traditional pine or even composites. Thinking also about maintenance and durability, as even a treated pine deck doesn't really last that long here in the south, I was considering using Black Locust that I grow on my own property as the primary material for both frame and deck, and I like the fact that it'll grow right back. I was actually thinking of doing a timber frame style support system and milling the deck boards on my 14" band saw. I'm aware that Locust is a very dense wood when dried, but how is it fresh cut? Is it dimensionally stable in a green state? Would it need to be dried first? Will I even be able to get a drill through it? Are there any other considerations I need to take into account?

I appreciate any help or input I receive for this conceptual phase of the design. If this project works I may adapt it to other building projects on my property, because I could really use a workshop and other out-buildings.

Thanks

Hey Victor,

I'm aware that Locust is a very dense wood when dried, but how is it fresh cut?

Like oaks, but grainer, and the silicate in the wood will dull the blades faster when milling with any saw other than a swing blade with carbide teeth.

Is it dimensionally stable in a green state?

No, but not any worse that other hardwoods in general (depends on the quality of the log you cut your Bolts out of, and how you treat your Cants...much more to that discussion) Pines and other conifers are of course much more dimensionally stable, but you have already outlined there other shortcomings. As a Timberwright, I design the frame to compensate for the dimensional shifting of the wood chosen.

Would it need to be dried first?

No, not at all, and I would say a very bad idea in general. I, however will except that is is a subjective view, as I am a green woodworker and a Timberwright. I will validate that I work both green and dry wood, have done it for decades, and only here others criticize "green woodworking" that no really nothing about it or have done much.

Will I even be able to get a drill through it? Are there any other considerations I need to take into account?

Yes, and yes...

I appreciate any help or input I receive for this conceptual phase of the design. If this project works I may adapt it to other building projects on my property, because I could really use a workshop and other out-buildings.

If you are willing to do the leg work, do photo documenting, and "journel" the entire project to be posted here on Permies.com, I will help you with all the technical aspects of this project while you learn to do it. (I will help you anyway...so don't feel pressured )

This is a perfect project to outline some skill sets and modalities that I had been planing on writing about. It would be much better if folks could see a "novice" to the craft do it, instead of me. There are some tools you may need to purchase, and one that could really change the approach and speed at which you cut the frame. PM me and we can discuss how to proceed.

Regards,

j

Great thoughts from Jay. I think locust is one of the most desirable appalachian species for exterior exposure. Ive heard that whole logs tend to resist rot more than sawed ones. Its a serious pain to work with being so dense and will dull blades faster than just about any wood Ive worked with.

There are some things you can do to treated pine to make it last longer: tape the top edge of framing, use ledger spacers, use hidden deck fastening systems (fasten master's is my favorite). Instead of typical sized board decking, use 2x material. I think a well detailed PT deck could last longer than a poorly detailed locust one.

Here is a pic from one of our projects with a whole log post and locust carrying beam. http://www.houzz.com/photos/2242728/Springtime-Cottage-at-54-Swanger-traditional-exterior-other-metro

Thanks for the input, Brian. Like your pic.

Another thing I heard recently about black locusts is that if it's not debarked it'll rot just like anything else. Not sure if it's true, just something I heard.

To reduce milling, I was thinking of using primarily stripped round-wood poles and saving the milling for the deck boards and maybe the top side of the joists to get a flat nailing surface. Still have a lot of research to do and my locust timber grove has lots of growing to do before its ready, so who knows how things might change. That being said, please keep the info coming. My favorite part of projects like this is the research and conceptual design. The more I dig in now, the better the end result will fit my needs and the more interesting designs I'll be able to come up with.

Victore.

Two things, i don't know what your bandsaw is, but you said 14", so i guess it's no sawmill. I would say, save you the chore, and get a mobile sawyer to saw the wood for you.

And for black locust to last a long time, it's better to split it, as most of the woods too. But split boards for decking might not look that good

Victoria-

I work for a company that sells black locust- a couple things... definitely dried- not green. after its dried, you HAVE to predrill. otherwise you will bend your nail. if you don't believe me, just try it! It is highly rot resistant- i wouldnt use pressure treated lumber period as it is not an environmental product and it rots anyway... if you have locust near you, saw it up, dry it down, pre drill and enjoy your deck! Also be aware that locust has no structural grading. therefore you can use it as a structural element- i e timber framing. if you dont intend to pass your plans along to a building coder, than it will hold up, however, just know that the law does not allow for bl to be used as a structural product. Have fun!

Brian Knight wrote:Great thoughts from Jay. I think locust is one of the most desirable appalachian species for exterior exposure. Ive heard that whole logs tend to resist rot more than sawed ones. Its a serious pain to work with being so dense and will dull blades faster than just about any wood Ive worked with.

There are some things you can do to treated pine to make it last longer: tape the top edge of framing, use ledger spacers, use hidden deck fastening systems (fasten master's is my favorite). Instead of typical sized board decking, use 2x material. I think a well detailed PT deck could last longer than a poorly detailed locust one.

Here is a pic from one of our projects with a whole log post and locust carrying beam. http://www.houzz.com/photos/2242728/Springtime-Cottage-at-54-Swanger-traditional-exterior-other-metro

Brian, how did you make the large shingles? Did your team de-bark the tree? I'm very interested in shingling/shakes and the process for identifying the correct trees.

Tari Jay wrote:Also be aware that locust has no structural grading. therefore you can use it as a structural element- i e timber framing. if you don't intend to pass your plans along to a building coder, than it will hold up, however, just know that the law does not allow for bl to be used as a structural product...

Sorry Tari, that is not my experience at all. Our PE authorizes and has approved many timber frames for my designs, as well as others in the Timber Framing Guild over the last 30 years. We have several frames with it going on at this moment, and an entire structure less than 6 miles from me (photos on line) that sits on these "structural posts."

I would agree that if you DO allow the wood to dry before working it, it must be pre drilled as Tari suggested, and you will dull your woodworking tools much faster on this species...especially when it is dried. If you study any of the "green woodworking" books or teachers you can approach this species in a more traditional fashion.. I have laid deck, built frames, and even outdoor furniture (and some indoor) out of very green (wet) Locust...so it is not a matter of "it can't be done" but "how you do it," that matters.

Brian I am sure will add more but for Locust Shakes you want the largest tree bolt sections you can get, and if you do leave "sapwood" on the shakes these will need to be properly oiled to enhance the lesser rot resistance of this type of wood.

Regards,

j

Yeah I would agree with Jay. I think there are span charts for Locust too but Iam not sure. The beam in that picture is locust and spans about 8-10 feet of roof load.

Chris, the bark shingles are Tulip Poplar bark. Its one of the best claddings/sidings available on the East I think. Weve harvested it before but I think that house used commercially bought product. There are homes in the Linville NC area with original bark thats 75-100 years old. No paint or finish necessary is my favorite part besides the looks of course.

Its pretty labor intensive but straightforward. You have to peel it when the sap is flowing from freshly downed trees about 10-12' sections long work good. I think 18" is a minimum diameter to yield the 3/4"-1.5" thickness necessary for exterior grade. Zip up the trunk with a chainsaw to start peeling with dull chisels or wedges. Cut the curled sections up to around 3' to fit on a pallet. Flatten between 2x stickers with heavy duty cam straps asap. Might need to tighten the bundle up as it dries which is best done in a kiln but Ive use clear plastic in the sunshine with good success. After its dry, you can square/cut up the top and bottom with a table saw to around 18", cut the damaged areas and square the sides with a chopsaw.

I remember hearing that there is another species that works for this but cant remember what. Anyone? In my experience, poplar is the only species whose bark holds together in sheets like that. I know the old timers did it with chestnut too..

Thanks Jay and Brian, invaluable information.

I always wondered if it is better to search out tulip poplar for the bark or if there is a wider number of species that can be used with the shou-sugi-ban technique. I don't know how to control the exposure to the fire, how hot it needs to burn or for how long to create a resistant, safe exterior cladding but it is very beautiful in it's own right.

I will have to bookmark this thread, as it's full of great information.

Silly me...Chris...I thought you had been talking about locust shakes...dawww...

Tulip Poplar is a magnolia and the bark off this tree is incredibly durable for a siding material as Brian has shared...it is awesome. If you treat it with a traditional oil finish or other fixative, you can easily double the life span...by itself you should last 100 years with nothing at all on it.

White Ash bark can be done this way as well, as can red wood, some paper birches, cork (of course) and there are more. I would also note that plane old "white pine" if oil with pine tar oil and placed properly on a 12/12 pitch or greater will last well over 50 years (some over 100 years.)

As for shou-sugi-ban, probably better know as yakisugi (grilled cedar) 焼き杉 is another awesome finishing affect for wood to extend its lifespan. For method...experiment, otherwise one way to do it well for a novice is to use a "wood fire retardant" that will not allow the wood to stay ignited. This material is relatively inexpensive and helps the novice with this modality of treatment.

My friend Steve Sass of Crestline Industries will talk to anyone about their product line of wood fire retardants.

Good luck,

j

Dear Jay-

I apologize I was wrong! I have have been corrected that if you want to use it as structural application, that one must send it out for testing and recieve approval to get it tested. I know that it has no overall structural grade in many areas, but of course this changes on a regional level. Is tthat your experience?
j

Hey Tari......Welcome to Permies.com!!

I didn't do that the first time...apologies!

I try (have learned this better over the last few years) to stay away from "right and wrong."

I think I know what is...probably...the challenge is so many folks are given info from a "limited scope," or from outside a "context use," that is typical. I would have to know exactly the area to give (perhaps) a better understanding of what "may be challenged" by those in the "departments of sadness," (code officers.)

In general, big projects have a PE as part of a team, there isn't very much of anything a code officer can do but complain. There are areas, for example, like North Carolina where "lumber stamps," are used as "blocking tools" by some officials...yet...there are even ways around this for the natural builder...and the ways are expanding.

In all my years I have only had to have lab analysis of historic materials and never new materials? Nor do I know of anyone that has had to "send it out for testing or receive approval for testing either," unless it is a very unusual case and perhaps in a public (school, hospital, etc) or commercial setting. Even then it has never been an issue to use "atypical" species as these types of architecture (public-commercial) demand the use of a PE, which we have our own that always is part of the team for such cases.

If you don't mind sharing (no names necessary) where is your information coming from. It is most likely a breakdown in "scope or context," that is presenting confusion. There are charts/tables that provide professional engineers and folks like me with information on modulus of rupture, elasticity, compression...etc, etc....so it is not necessary to have "structural grading" charts or approvals...we do that ourselves.

Thanks for coming back to the conversation, we hope you enjoy sharing and learning here!

Regards,

j

Victore: Just a quick comment about your 14" bandsaw for milling black locust.

Honestly, I don't think you have any hope of doing that. I have been milling wood for 15 years using an old Lumbermate bandmill. It will cut through just about any sort of wood, some better and faster than others. On the west coast here I find Douglas Fir, various spruces, arbutus (you call it Madrone) red alder, red and yellow cedar, a couple of the pines etc.

There are a number of these small backyard type mills available, and I would suggest that you look in your area for a used one that is still working OK. The bottom line about this is that you can cut whatever wood you want to at your convenience. When you are done cutting, you can always sell the mill. My cost to cut wood over the years has averaged just 4 cents a board foot, and my logs have been dragged in from the ocean...in other words, driftwood.

One final thing. If you do find a suitable mill, get a sharpener and setter for the blades. I have recouped the cost of these last two items many times over. Blades are not that expensive, currently about $28 each for a 1 1/4" by 7/8 pitch by 144" long. It's the cost of sharpening that hurts. Locally it runs around $17 per sharpening/setting. You should be able to get 10+ sharpenings per blade, and at least 2,000 board feet (sometimes more) from each blade.

It is a small investment up front, but the long term benefit is well worth it.