Hammer beam questions

[Chainsawmill661]

Earlier this year I started milling lumber from trees downed by hurricane Ida that fell in my area. I'm building a small cabin, at the time I picked plans from timberframehq for a 16x24 hammer beam cabin, my thought process being I had mostly shorter logs to mill and so smaller members would be better.

This is my first frame and like usual for me I started building first and did research after! I've read a lot of threads here about the problems with hammer beams and needing buttresses etc. I'd have gone a different route but all my material list is milled and the first bent complete

 

Now I'm getting concerned about strength of the structure and movement of the posts over time as i will be enclosing and living in this. Was wondering what you guys thought, the span is 16 feet. I feel like i have 3 options

1. Roll with the plans and just build the other bents and trust the guys at timberframehq know what they're doing

2. Get a local shop to fabricate tension ties between the hammer beams, i don't prefer this option as i don't like the look of the ties

3. Put this bent in the middle and make the other two into queen posts by swapping out the hammer beams on each side for a 16ft 8x10. This would involve getting back on the mill which I'd rather not do or buy the beams from the mill down the road

Any thoughts or suggestions?

[Jim_Rogers]

A simple solution to the outward thrust against the post would be to put an iron rod tie between the hammer beams holding them together. Or a cable with a turnbuckle so you can adjust it in the future as needed.

Jim Rogers

[Stephen1]

Sometimes we have to live with our mistakes or imperfections, especially when we blast into a project with little to no research...lol, been there done that and still do. What Jim says is a great simple fix! I bet after a while you will not even notice the tie rod. But I always believe I can live with my mistakes but not ones I paid good money for.
 I put my basement foundation for my log cabin in a V of rock, I paid for that for 15 years, basement flooding, iron in the water, new sump pumps every year from the iron in the water seizing them up, back up sump pumps quitting , iron in the water. I just built a new house next to the Cabin and we dug out that V of rock from the cabin to the lake, almost. Filled the V with 24" of 1.5" clear stone, put my new foundation on that and all the water now runs from the Log Cabin under my new house to the lake.....Sump pump has not run since last year.  8) 8) 8)

[Chilterns]

I'm going to wait for Don P (our resident hammer beam expert) to provide alternate suggestions and answers to help resolve the issues and concerns identified by you (et. al.) before providing you with a quick fix solution (clue - no iron bars will be harmed) that is technically superior to the current arrangement.

[Don P]

 

[Carpenter]

We often get caught up in the details.  Yes, a hammer beam truss is a broken truss, because obviously the bottom chord is not continuous.  It does not have the same strength as a king post truss with the queens.  But, it does give some trussing action, (I probably just made up that word "trussing").  You're only spanning 16', so it's not a massive span, and only a 24' long building.  If you use three bents that puts your bent spacing at 12', again, that's pretty conservative.  What is your snow load?, and wind load?  Also, is there anything else bracing the building?  A wing on the side could also do the same thing as a buttress.  It's not rocket science, it's just maintaining equilibrium with the known factors, (dead load and live load).   
     That's such a small building, if there was a limited snow load in your area, I would probably just go for it.  (Please don't take my advice as the gospel truth, take this more as stock trading advice from a trader who lost millions on the last crash.)
     Your hammer beam truss looks very nice by the way.  If it does spread in the future, you could add some cables, or tension rods.  I've added tension rods to several old barns that have spread, we can't always bring them back to 100 percent true, but we can stabilize them.  
     I guess, my main point is that in the building trade, we make mistakes, we learn from those mistakes, sometimes we can correct those mistakes at a later date, and we move on.   

[Ianab]

I guess the question isn't what's the strongest, because if that was the case you would the whole truss from steel I-beam.  It's a matter of "Is this truss design strong enough for the job?"   

Gut feeling is that it will be, because heavy timber framing in a small building like that is generally way overbuilt. Looking at modern commercially built structures, they are engineered to meet the specs with as few 2x4s as possible, and are strong enough to handle snow / (small) hurricanes / earthquakes depending on where you live. 

No doubt a more conventional truss would be stronger (or a steel tie to reinforce that design). But if it's already got a 100% safety margin, do you need 150%?

If you do go with the steel rod, maybe combine it with the light fittings, making it look like it belongs, Or encase it in a fake wooden beam so it appears the main beam is continuous? Again the fake beam might make mounting lights easier.

BTW, the old building our town office is in uses steel tie rods with heavy Doug Fir truss design. When we moved in there was no false ceiling, exposed trusses and wooden sheathing under the roof. It's over 100 years old, so the idea of adding in steel ties isn't a new one, and holds up over time. It's been remodelled since with modern suspended ceiling, but the original structure is still there.