Hey all,

I have a couple of 4 bent barns that are failing in the same location: bents 2 and 3 tie beam to post connection. The pegs have failed and the walls are growing outwards as the roof sags downward. Folks who have tried repairing before I arrived have employed chains and steel cable which have stopped the progress of the failure, if only temporarily.

I have a number of great timber frame books that explain how to build new but have yet to find one that teaches how to (safely) fix old. Can anyone tell me of a title out there that addresses the subject. Is there an article in Timber Framing I have not found yet?

I'd love to craft an elegant and lasting solution for these barns. I am afraid that simply replacing the pegs is, while not disruptive to the historic fabric, a foolhardy solution as they have already proven to fail in this orientation.

I look forward to your wisdom and bibliographic references.

-Shawn

There is an article in Timber Framing on repairs. It is by Jack Sobon. He had the magazine with him last week, to show us some possibilities for our Dutch barn restoration. I don't know the issue number, but it was from 2003, if that helps. I plan on buying the TF CD, as there is so much info available in that magazine.

This book was published only a few years back and is already out of print - You could not buy it and go into the restoration business, but it is a primer on rigging and repair of timberframed barns, and is some of what you're looking for.

http://books.google.com/books?id=u2CNNwA...eFpnCyATrt9yLCA

Amazon lists it as out of print and unavailable, but at least has an image of the cover art -

http://www.amazon.com/Preserving-Old-Bar...5924&sr=1-1

Last I knew ( Last Fall when they finally opened a frame we built for them in '01 to the public ) the New Hampshire Farm Museum still had a couple of signed copies on hand, give them a call I'm sure they'd be happy to ship it to you.

http://www.farmmuseum.org/

It does sound like there is an insufficiency in the barns framing, is it just simple rafters ? With the ties doing all ? What is the GSL in your part of Michigan ?

Will,
Thanks for the tip on the book. I'll call the museum ASAP.

I don't have my copy of Jack's book "Historic American Timber Joinery" with me right now, but I recall him describing this dropped tie to post joint as common and also likely to fail.

The GSL is 90 PSF in Allegan County though the further you get from Lake Michigan that will decrease. Most of the barns I have met in Michigan feature 2" mortise and tenon joinery. One of these two barns is all white oak and the other is mixed hardwood. The posts are 8x8.

The load is carried by the 2x rafters to a scarfed top plate thence to the posts. The tie beam is in both cases about 2 feet below the plate. The only resistance to outward thrust was the pegs holding the post and tie together.

In most cases around here barns have been given many layers of roofing to bear up in addition to the snow load and farmers are loath to spend on removal and reroofing. I am not surprised these joints are failing but sure would like to find a solution to their problem.

In that vein, is there a preference out there amongst framers? Wooden repairs, steel brackets, chains, cables, ropes? I imagine it would matter if the barn was to be reused as a barn vs converted to a residence. It would surely make me nervous to live in a structure bound by steel cable but I image the cows and chickens don't mind.

-Shawn

Hey Shawn:

Some of these dropped tie-to-post connections had dovetailed or wedged tenons on the end of the tie beam, usually w/ a angled haunch cut into the post.

The dropped tie is not the best in my opinion. I've seen some barn books speak to this area/design as prone to failure.

Just a atraight tenon and a couple of pegs is really asking for trouble on this type of joint. Can you say "withdrawal?" Anyway, take another look at that particular barn and see if the tenon isn't wedged...from the outside under the sheathing if you can get to that area. Maybe it needs a new wedge (I know, too simple, right?)

Here's Sobon's book you mentioned. It's availible on the Guild's site as a PDF. Look at the dovetailed/wedged tenon (pg. 4) http://www.tfguild.org/joinery/part1.pdf


As far as guarding against future wall spread, once you get the walls back to plumb, or close, perhaps inserting some sort of ridge support is part of the overall plan? If the ridge can't sag, the walls can't spread. Maybe a number of vertical ridge supports is an option.

One should be able to view the wedge from the inside, on the top of the tie, they are through wedges. Most of the barns in my area have large staples/dogs installed to assist with this spread, I think it is helping.

Tim

Like you suggest it all depends on end use and engineering demands, we will sometimes inject even a timber system that looks out of place, so it will never be confused with original framing.

In your average utility barn I'm typically for doing the least visible and out of place looking repair that the owners budget will support, To at least try to keep it looking like it always has.

Sounds like a heavy steel strap over the of the tie, though the mortise and down the back of the post might be one way to go. But the bending issue would then return, how far is the drop ?

Introduction of a canted purlin post plate system to redirect much of the thrust directly to the tie and away from the wall plate might look and be appropriate, both now and originally...

There are umpteen approaches that can be taken.

But this isn't really forum fodder and isn't something to be conjecturalized about without much more information.

this post needs pictures, measurements, relevant snow and wind loads (thanks for posting those), etc... etc...

all solutions posed without at least some serious background knowledge of the situation is conjecture, fantasy, and potentially dangerous and / or expensive advice.


and yes, all those methods could / might / should work, depending on circumstances.

as to the comment on steel cable... when done properly it works pretty well... inside or out.

relax.