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ThisOldCabinNJ
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# Posted: 19 Dec 2023 09:15
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Hi Folks,
I would like your input on a design choice. I've narrowed my choices down to two options: square head nuts/bolts or standard hex head hardware. The former is a little trickier to acquire but hex bolts are readily available at the local box store; I have to source and have the square head bolts shipped.
So I'm going to plate and bolt two beams together that span over my living room area. It's going to be exposed/seen by anyone who walks in and using square head bolts would look absolutely awesome ( at least I think ). I plan to distress the steel plate to look like wrought iron and gun blue it so it looks period correct. The cabin is over 100 years old and although I love the old hardware, a lot of what was there wasn't kept in good shape and had to be updated to make it work in this modern world we live in. I have been trying to incorporate the 'old' along side the new.
That said, is this over the top? Should I just stick with regular hex head bolts? What about using carriage bolts and a hex nut? It would be much easier for me but I don't mind doing the legwork to make this smaller detail stick out. I'm strictly asking about this from a design aspect.
Thanks Much!
P.S. although it's not shown in this picture, the entire roof has been spray foamed last thursday. It's soooo nice to finally have the cabin insulated. Two years in the making.
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paulz
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# Posted: 19 Dec 2023 09:52
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Quoting: ThisOldCabinNJ What about using carriage bolts and a hex nut?
Carriage with square nuts maybe?
Nice looking place!
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Brettny
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# Posted: 19 Dec 2023 10:00
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https://www.oldwestiron.com/products/hcl-07-1-4-lag-x-3-8-square-head-lag?variant=328 81729568871
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ICC
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# Posted: 19 Dec 2023 11:51
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Quoting: ThisOldCabinNJ going to plate and bolt two beams together
Is this plate and bolt assembly structural or only cosmetic?
-izzy
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gcrank1
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# Posted: 19 Dec 2023 12:26 - Edited by: gcrank1
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Square stuff maybe from Amish store?
I agree that square is a very nice visual detail....that few will likely notice or appreciate. If you are like me You Will be pleased every time You look at it; and the extra expense will not be much compared to the rest of the project. They do add up though....picking stuff for such at eye level is more quickly seen, but then you start a 'theme'.....
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ThisOldCabinNJ
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# Posted: 19 Dec 2023 14:35
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Quoting: ICC Is this plate and bolt assembly structural or only cosmetic? -izzy
a little column a, a little column b. There is nothing going on top of the beams so structurally they just needs to support their own weight and keep tension on the roof rafter so the sill plates don't spread when there's a snow load. What's there now is far better than what was there before (which was nothing).
I found a hardware vendor (Ziegler Bolt) that looks to have square bolts, nuts, etc. however they seem to be out of stock in certain sizes. I think I was able to source it all. That OldWest Iron store looks great but their products seem to be a little costly
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ICC
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# Posted: 19 Dec 2023 16:48 - Edited by: ICC
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One of the things Old West Iron is good for, is that their square head fasteners do NOT have any letters, numbers or codes stamped into the head. IIRC they have ones with what appear to be hand-hammered heads for a very rustic look. Some people will pay handsomely for that.
Try fastenmaster. I believe we used them years ago.
I ask about structural because a through bolt, with washers or plates and a nut is stronger than lags. Carriage bolts may be okay but may require upsizing as most carriage bolts under 6" length are all-thread. A 1/2" all-thread carriage bolt is only about as strong as a 3/8" machine bolt.
Carriage bolts longer than 6" still usually have a 6" threaded length and that reduces overall strength compared to a regular bolt.
-izzy
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Brettny
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# Posted: 19 Dec 2023 18:10
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If theres no ridge beam in that cabin those would be structural to me. Mine gas something similar in a 12' section with a cathedral ceiling and I consider that structural. It's there to keep the walls from bowing out.
In the future mine is going to be a 6in round by 20' long ash log.
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Brettny
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# Posted: 19 Dec 2023 18:13
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Actualy looking at the gabel end framing those are structual. You have a ridge board.
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Fanman
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# Posted: 19 Dec 2023 19:22
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Quoting: ICC A 1/2" all-thread carriage bolt is only about as strong as a 3/8" machine bolt. Carriage bolts longer than 6" still usually have a 6" threaded length and that reduces overall strength compared to a regular bolt.
The length of the threaded portion will not affect the strength of the bolt in tension; it's still only as strong as its weakest point, across the minor thread diameter.
In shear, the strength will be reduced if the threads cross the parting line between two components. That's where the bolt with the longer unthreaded length will be stronger; the parting line should be where the bolt is solid and the threads only holding the nut at the end.
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ICC
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# Posted: 19 Dec 2023 21:10 - Edited by: ICC
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Thanks for expanding on the theory behind the strength between unthreaded and threaded portions of a fastener. The situation in question seemed to be shear forces on the fastener unless one severely overtightens the bolt so I took the simple response. Full explanations are more educational.
Re-reading the OP, I have another question. Quoting: ThisOldCabinNJ I'm going to plate and bolt two beams together that span over my living room area.
Does that mean two lengths are being butt spliced with steel plates on each side and bolts clamping the sandwich together around the butt ends? (I hope that is clear to visualize). If so the joint may be stronger if more, but smaller bolts are used instead of a few larger diameter bolts. That is because when the two beam pieces are under tension the bolt pressures will be spread out over more area. Holes should be staggered to help spread the forces out as well.
Are the two beams in the photo the ones the bolt question is for? Or some other new beams? The " I'm going to" phrase originally led me to believe this is a new, not yet done thing. Now I am not sure.
-izzy
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ICC
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# Posted: 19 Dec 2023 21:27
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EDIT: The engineer in the family told me the carriage bolt shear might be about 15% less than a machine bolt of the same size.
-izzy
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gcrank1
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# Posted: 20 Dec 2023 10:31
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I know they are out there but finding 'better than butter bolt' carriage bolts may be harder than expected and expensive.
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spencerin
Member
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# Posted: 20 Dec 2023 11:30
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Sounds to me like it's purely a matter of what YOU want. If you like the square head look and don't mind the extra legwork and cost to obtain them, our design opinions don't count.....
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ThisOldCabinNJ
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# Posted: 21 Dec 2023 07:57
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Quoting: Brettny Actualy looking at the gabel end framing those are structual. You have a ridge board.
thank you all for the additional input. you are 100% correct: that is a ridge BOARD (not beam) and yes by all technicalities the 2x8 beams installed ARE structural. I have to watch who I use words like structural/not structural around because when I mention they're structural, its' assumed by the layperson that they're meant to support a second floor above them (i.e. a loft). The beams were put in because when the cabin was built last century (ca. 1922) they had no rafter or collar ties. Its crazy to think they believe this was ok, especially with log walls that can roll. I added collar ties throughout the entire roof structure and added rafter ties above the other side of the cabin (unseen. the photo was taken from above what is now the bedroom and bathroom). The photo seen is the other half of the cabin which is my living room/kitchen area. It's about 20' across (with the beams being butted up against one another) by 14' for refernce.
At some point in its life, the roof structure bowed in from the lack of proper structure during a heavy snowfall (at least thats what I've concluded). Logs pushed out on one wall and pulled in on the opposite wall. A previous owner then installed a threaded rod through the sill plate as a future preventative to spreading - whilst this may have helped, this was not enough in my or my arsenal-of-engineers opinion ( I have several family members who are structural engineers and others who are mechanical). One thing we all had agreed on is NOT try leveling out the roof as it's kinda petrified in that position. We opt'd to just add structural elements to keep it from further spreading.
Quoting: ICC Does that mean two lengths are being butt spliced with steel plates on each side and bolts clamping the sandwich together around the butt ends? (I hope that is clear to visualize). If so the joint may be stronger if more, but smaller bolts are used instead of a few larger diameter bolts.
This is almost exactly what's going on. At this moment, the beams are spliced together with a 2x4 and screws (temporarily - I'm waiting to have to have the plates manufactured) until I get the plates and can bolt everything together. They are also being picked in the the center by a pier wall (2x4 wall) so they don't sag. I had to rush and get these beams in place before the spray foam went in - which at this point, that part is completed.
Anyhow, to be clear, BOTH SIDES of the butt-splice will get a plate (I opt'd for 3/16" HRPO steel plate, aprox. 7" x 18" ) and then bolted. My plan was to use 1/2"-13 square head bolts; 5 per side - so 10 total per beam. In the picture above (the plate/bolts part is photoshopped in for reference), I have the bolt pattern. From what you're suggesting I should really use smaller bolts, more of them and shy away from carriage bolts or at least full-thread carriage bolts??? I did have concerns about the bolt size and how that affects the shear strength of the wood which is why I went a little bigger. Power in numbers isn't always good I guess when it comes to size.
So would you recommend doubling the number of fasteners and using a smaller bolt size like 3/8" ?
Quoting: spencerin Sounds to me like it's purely a matter of what YOU want. If you like the square head look and don't mind the extra legwork and cost to obtain them, our design opinions don't count.....
Well yes and no. While I may not agree with an opinion, I try to ask questions, listen and take away information from EVERYTHING I learn. It's that whole "I know there are things I don't know" theory. I also have this bad habit of seconding guessing, third guessing and fourth guessing myself. Another reason why I'm here asking you all for your input 
That said, while I am still leaning toward the square head bolt look, I am certainly now re-considering bolt size and quantity of bolts regardless of which way I go.
Thanks Folks! As i mentioned above, I know there are things I don't know and as my favorite college professor always said " the more you know, the more you know " - albeit I believe he would say that jokingly. He is also quoted saying " laziness is the key to efficiency " LOL really meaning work smart, not hard - the lazy man has the most efficient way to get a job done.
Regards,
-al
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gcrank1
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# Posted: 21 Dec 2023 11:32
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Im no engineer.....
Have worked on a lot of different stuff though. The bigger the stuff the bigger the fasteners.
Ime it goes like this:
Butterbolts are soft (basic hardware store fasteners)
Grade 5 is lots better and a lot of car stuff is that.
Grade 8 is really heavy duty, Caterpillar uses a lot.
Past that they lose 'tough' for 'brittle'.
Wonder if you can find info on what would be used on the old time wooden bridge building/restoring for the lumber size you are using?
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ICC
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# Posted: 21 Dec 2023 13:26 - Edited by: ICC
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FYI, in your situation, with two steel plates sandwiching the wood main member, the construction fastener calculator I use indicates the limiting factor is the wood member.
With a 1-1/2" thick Hem-Fir wood beam the following is the calculated allowable shear force on...
... 1/2" machine bolt, 519#
... 3/8" machine bolt, 388#
DougFir is 820# at 1/2" and 520# at 3/8" Other species vary. You could have a look at this AWC calc.
Those are common, unmarked grade 2 bolts. Wood is the weak point, IMO nothing is gained with higher grade bolts for something like this.
Likely 6 - 8, 3/8" bolts would be fine, holes staggered somewhat so as to not be along the same grain line in a longitudinal pull.
Support on a wall would be great to avoid sag. Ideally, the wall is under the splice.
Or hang the spliced beam from the ridge beam as a King post. That would be best done with T-shaped steel plates that would allow sandwiching the horizontal members as well as grabbing the vertical king post. King post is in tension same as the horizontal beam.
-izzy
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Brettny
Member
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# Posted: 22 Dec 2023 18:27
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How wide is the cabin? Can you make it out of one piece of wood and just to the metal for decoration?
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ThisOldCabinNJ
Member
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# Posted: 23 Dec 2023 09:50
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Quoting: ICC Those are common, unmarked grade 2 bolts. Wood is the weak point, IMO nothing is gained with higher grade bolts for something like this.
^^^THIS. Thank you. Was my instinct I just didn’t do the math/research to prove it.
[quote=Brettny] How wide is the cabin? Can you make it out of one piece of wood and just to the metal for decoration? [/quote)
It’s 20 foot wide. I wanted to do a 1 piece beam however the ONLY way to get that long of a beam into place would be to cut a hole in the roof sheathing and slide the beam in along side the rafter, then patch the roof. Unfortunately between time not allowing for that and the fact I didn’t want to cut open a fairly new roof, I opted to bolt them together. I know this isn’t the most ideal but also know it will work if you have right hardware/splicing materials. As ICC mentioned above the wood will be the weakest link anyhow (does anyone else hear “you are the weakest link, goodbye†when someone mentions that phrase? LOL).
There’s a lot I’d like to do differently but have to compensate for the sake of getting it done.
Thank you again!
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gcrank1
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# Posted: 23 Dec 2023 11:33
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How about:
Perfect is the enemy of good enough 
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