patch beam question

I have a 20' span I need to install an 8" X 8" X 20'3" beam in between. I don't enough room left on the beam for a proper mortis and tennon joint. I do have enough room for a shoulder on each side. It is on the end of the building with no siding and I have full access to the outside and front of the joint. I am considering cutting a shoulder on each side. I was then considering counter sinking a steel plate with holes for a (3) 1/2" thick lag and pulling the shoulder into the beam using a the lag bolts.

I think of it as using a big lag bolt and washer to pull the oak beam into the shoulder. Has anyone succeeded with a repair like this? I was wondering if the building moving with the wind would be enough to loosen the lag bolt?

Picture posting:
Is there a post with instructions on how to do this? I think I need to have the pictures posted on the internet somewhere to allow linking to it. Is there a way to upload the picture into the post directly?

No way that I know of to upload directly.
You need to find a picture hosting site and upload it there and then post the link here.
Good luck.

Jim Rogers

I have a 20' span I need to install an 8" X 8" X 20'3" beam in between. I don't enough room left on the beam for a proper mortis and tennon joint. I do have enough room for a shoulder on each side. It is on the end of the building with no siding and I have full access to the outside and front of the joint. I am considering cutting a shoulder on each side. I was then considering counter sinking a steel plate with holes for a (3) 1/2" thick lag and pulling the shoulder into the beam using a the lag bolts.

I think of it as using a big lag bolt and washer to pull the oak beam into the shoulder. Has anyone succeeded with a repair like this? I was wondering if the building moving with the wind would be enough to loosen the lag bolt?

Clairification:

The rear wall is in the construction process. I have added and pinned the beam to the far left edge. The right side has not been installed yet. Below is the beam I want to use. It already has the center drilled and mortised for the center support (not shown). The real problem is the ends (see below).

Both ends have "mortise" where I need "tenon". I want to keep the orientation of beam so I am somewhat limited. I was thinking of cutting it almost flush and cutting a into the side of the building's beam about 1/4" deep and 8" X 8" to form a indented shelf (I am sure there is word for it). I would then raise the 20' beam into position and pull the beam into the shelf with lag bolts. The lag bolts would be installed parallel to the grain. I have some 1/2" by 16" lag bolts. I would install a plate to spread the load out on the existing beam. Any thoughts about the lag bolts loosening up or pulling out? I have never seen this done and I wonder if there is a reason why.

Note: Please excuse the post quality, I am still learning the software.

Since you can not post pics, can you sketch what you are talking about and post it? A bit hard to understand from the description. Additionally, where are you from? In your profile, there is a spot so it will show where you are from on the left side of each post. It helps, in case you are nearby someone and they can help etc. Someone might have a better piece of material you need to do the proper mortise and tenon etc.

I am going to attach post B into the existing post A on the left. I will drill a plate (in red) on the outside of post A and insert 2 or more lag bolts (in white)and pull post B into post A. I will cut in a "shelf" (pictured in blue)and Post B will be drawn into the "shelf" in Post A. I didn't photo shop in the left side, but I want to use the same plan.

I am located near Bowling Green, OH. I will update my profile as time permits.

Your drawing helps quite a bit, but in the future a "post" refers to a vertical timber and a "beam" refers to a horizontal timber.

As far as your plans, its not a good idea. Screws or lag bolts have no reliable strength when screwed straight into end grain. You would be better off toe-screwing the lag bolts from top of the beam into the post. Your idea of using the "shelf" or shoulder cut into the post is a good idea and should be kept.

I would suggest using a free-tenon, since you don't have the length for real tenons. In conjunction with the free-tenons, the shoulder is a must and the lag bolts toe screwed wouldn't hurt.

good luck

I agree with bub4e, screwing into endgrain (screwing parallel to the grain) is never a good idea. Very low holding power and more prone to pull out. A shoulder is a good idea. By free tenon, I'm assuming he means a 1.5 inch long tenon on each end with no peg. This will key the beam into the posts and prevent horizontal movement perpendicular to the bent. A free tenon would be better than no tenon. Another option instead of toe screwing and free tenon is to use a spline.

In your case, you'd peg the spline in the post and beam. Use something strong and stable for the spline, Walnut, white oak etc. This would be a more elegant solution, and would avoid the use of metal hardware. Steel and wood don't really mix over the long term, in oak especially. The acidity will corrode the metal hardware and rot the wood surrounding the screw over the long term. Timberloks, which you may be thinking of using, are better in that they are epoxy powder coated, which would be longer lived than exposed metal or zinc plated.

How about the same plan, but with the lower lag bolt angled up at 45 degrees and the upper lag bolt angled down at 45 degrees? That way I would be crossing the grain instead of riding parallel and risking a split that releases the tension on the lag bolt.

check out the below link and look for "splined with tabeled housing" joint. I would also increase the housing (shelf) depth to something more than 1/4"...
http://books.google.ca/books?id=AX9nvlKG...non&f=false

timberlinx is another option

I like the Timberlinx solution (model A475). At $25 each they are out of my price range. I think I could use the same solution with a piece of thick wall tubing and a long grade 8 bolt. How deep would you recommend for the housing (shelf)?

Brad, when I said "free tenon" I mean the same as the "spline" that you have pictured. I agree with the bare metal not being the best solution. A couple lag bolts or timber screws in addition to the free tenon/spline wouldn't hurt.

As far as putting the screws through the post and into the beam at an angle, while better, it is still not as good as toe screwing.

The timberlinx seem like a good idea. I've seen some home-made timber fasteners that look like a super-sized bed bolts. If timberlinx cost $25 you are probably better off purchasing them over building your own, but really they do essentially the same thing as a free tenon/spline, so that's what I'd do.

For the housing (shelf) I'd go at least 3/4" but no need to go more than 1"

http://www.tfguild.org/publications/glossary.pdf

Seeing that timber framing has some terms not often used in conventional construction, this glossary provided by the guild is an excellent resource.

I try to use traditional frame joints when I can in my barn restoration efforts, but I have used a bolt system to tie lean-to additions to TF buildings.



Rooster

Good luck drilling the holes!

This is a bit unrelated but still on topic. Joist hanger have a purpose other than joist. It has been suggested they can be used in old mortices as reenforcement. As in a tie beam with a principle rafter where the quality of the wood at the relish is in question.

I take it that it is not the bare metal which is the problem with the black stain and deterioration of the wood but that the metal has different properties with temperature swings and moisture condenses on it repeatedly over time, rots the wood. For these new fangled coating on fasteners time will tell, we just have not had enough time. So is the coating there to keep the fastener from corroding or the keep the wood from rotting? Will you still get a rotting action around a screw over time, it just will not be black? Hangers are galvanized.

There is a lot of steal use in old timber work, from queen rods to small 3" dogs.

I would not feel comfortable using lags to tie the tie to the post, even toe nailed. 1" at least on the housing. I have seen a heavy 1/4"x3" strap used on top of the tie, say 3'+ long and running through a hole in the post and nutted on the outside face of the post. Weld a rod or black smith a round shaft with threads. Low tech, simple and it addresses the issue.

Tim

The picture of the generic spline in my previous post was from a frame by
Mark Gillis, P.Eng.

Gillis & Company Timber Frames

6240 Summit Street

Halifax, Nova Scotia, B3L 1R7

I was contacted by him and he was not happy I used his photo. I was not trying to claim credit for his work, but merely googled for a photo to illustrate a generic spline joint for information sharing purposes only with the poster. My apologies to Mark Gillis.

wow, sorry to hear that Brad..days must be slow in NS

I must take a momemet and apologize to Timberlinx for using one of their photos posted on their site

IMO, you have nothing to apoligize for, sir

Although it wasn't crystal clear from your post, I don't think anyone would think you were trying to take credit for someone else's work. However, by linking to his picture, you were using his server bandwidth. Mark may have overreacted, but I've met Mark, and he's a good guy. CB.

So I'm interested to find out which solution Barnmover picks...