Hi all:
I'm working on a quote to restore and re-raise a barn frame and have a question on timber repair....
some of the posts(11x11) in the frame have hollow sections. I would like to repair these by placing sound wood into the hollows. I have ideas on how to proceed but would also like to contact those with more experience in this area. My main concern at this point is whether to repair a post with a hollow that is above the crossbeam mortice? The roof on the new building will be made of conventional trusses, so thrust is not an issue, but wind load will still be there. Thanks in advance,
-Mark in Ontario.

Working with the guild on a project some years ago we were taught to remove all rotten wood, cut back to good wood and join the new wood to the good wood.
Filling in rotten wood without removing the rot could let to continued rot and maybe into the new wood.
Jim Rogers

were you joining with epoxy, bolts, glue?
I'm partial to bolting, as it can be taken apart(for the client or building inspector), and the folks I'm building for don't mind looking at steel.
Thanks for the reply, Jim.

Mark,
replacing post sections can be accomplished with half lap joints which are then bolted thru.
Make the laps twice as deep as the dimensions of the posts. Example a 12x12 would be lapped 24" in longitudinal depth. 1" carraige bolts with washers at nominal 6" intervals (3 would be required on a 24" lap) Do not put the bolts in a straight line but offset them by 1/3 of the short dimension with the center of the 3 in the short dimension middle.
Clear ?
deralte

clear as a bell, deralte!!!!
what if the timber only needs a 6x6 repair on a corner? would you follow roughly the same process:
-create a 6x6x24 inch cavity, then lap the cavity material out into the post (3x6x12) above and below the cavity
I'm thinking 4 half inch bolts(2 on each end) would hold it together...

this would be fine near the bottom of the post, but I'm not as comfortable doing repair of any kind above the crossbeam tenon.

would you do the half lap join you describe above the crossbeam?

Mark,
Am not all that sure that I understand your latest question. The cavity word is confusing. Repair is only accomplished using new material butting into sound old material of the same cross section size.
Half laps make good joints for posts and sill plates. Scarf joints for plates/girts/ties above ground.
Half laps were common in sill plates on the corners with a square tenon from the post bottom into the lap.
Bolt diameters are a nominal 10% of the cross section of the timber being secured (a lil less is ok). Do not expect any real holding power with bolts less than 3/8" diameter. And dont forget the large flat washers on each end to minimize the compression of the wood around the hole.
Your turn.
deralte

again, my concern is doing repair work near the top of a post, above the crossbeam mortice. I see this as the area of the post that has to work the hardest when the wind blows.
I was asking if you would use the repair you wrote about at the top of a post?

what i meant by cavity is that there are places where it would be stronger to "patch" the posts, than it would be to cut off the post and add a new piece of full sized timber.

I appologise for my confusing writing,
and thanks for your replies
-mark.

Mark,
repairing using a half lap on the post tops above the ties/girts is more a question of how tall is it ? if the half lap requirement of 2x timber size is longer the needed height then no, more appropriate to replace the post (yes a lot of work)
"patching" with new material after removing any decay/bug damage/etc is ok if you are not going more than 1/3 of the way into the post.here comes the Gorilla glue so the patch and the original become one. be wary of different moisture content (old vs patch). the posts are normally in compression so they are sensitive to any bending moment (normally resisted by the braces). If you are more than 1/3 of the way into the post you have effectively changed its length and the predictable forces of any bending moment become very cloudy. scotch tape and bailing wire do have their limits.
sometimes working safe takes a little longer.
am off to the Ferry Farm project tomorrow so will be away from the forum for 10 days after tonite.
deralte

At the recent TTRAG conference is was mentioned that you should try and complete repairs with new wood and try to keep as much "historic fabric" as possible.
These repairs are site specific and need to be addressed by the location of the repair in the timber whether it be a post, sill or beam. In addressing this repair you have to look at all factors such as stress on the post and what type of joint will replace the rot and not lower the strength of the post.

It was also stated that it usually cost less to repair a small section of the post then to replace the entire post.

Sometimes that needs to be looked at carefully in regard to two circumstances. If the structure is un-assembled it's easy to just copy an entire piece and replace it. If the structure is standing it's sometimes easier to just repair the damaged area.

Good luck with your project.

Jim Rogers

Thanks for the replies on this thread.
I had temporarily forgotten that one of my co-workers recently spent a few months at a french monastery, where he participated in timberframe repair. He was able to shed some light on the subject and certainly came down on the 'patch where possible' side of the debate. I like Jim's comment that timber restoration is site specific and the same patch may not work in all spots. Also Emmet's comment on bolt diameter being a nominal 10% of post size seems sensible to me.
This frame will be disassembled and delivered to our shop, so it will be possible to have a good look at the timbers, and make better decisions. I also plan on drawing out the repairs and forwarding the drawings to the project engineer. Anyone else with restoration experience who would like to add to the thread, I would appreciate it.
Thanks again!