Introduction: More Timber Framing Joinery: the Tie Beam
There are many components to a timber frame building. If you have read any of the other articles I have written here you will find more information on the joinery. Today we will be talking about more tie beam joinery, I have already covered the scarf joint which is a major portion of the tie beam. Other than the scarf joint we still have to cut a tenon, floor joist pockets, and a brace mortise.
Step 1: Imperfections in the Timber
When dealing with timbers of this size there is bound to be some imperfections that you will have to deal with. On this particular timber I had to deal with a large amount of wane. Wane is usually found on the corners of the timbers where it was not possible to completely square the edge off.
What I do is snap a line down the middle of the timber with that midpoint being measured off of the reference face and then I will layout my joinery from that line. Now this can be an issue if you have a heavy crown in the timber, as a side note the crowns are always pointed up. There are other ways of dealing with crowns in the timbers but we will cover that in a different article.
Step 2: Cutting the Tie Beam Tenon
The tie beam needs to be attached to the wall post. This is going to be a mortise and tenon joint. On the tie beam I need to cut a tenon. This tenon will fit into the mortise in the wall post. I cut my tenons on my saw mill, it is a fast and accurate way to make the cut and saves a multitude of hours over the course of the project.
When you are laying out the tie beam or any of the joinery for your structure you need to look at the timber and try see any problem spots you have in the timber that might make it hard get quality joints. These spots are usually large knots in the timbers that you want to try and avoid. This is not always possible but if you cut your timbers long then you will have a better chance of avoiding large knots.
As in all of the joinery in this project the tenon gets laid out from the reference face.
Step 3: Cutting Joist Pockets
These tie beams are supporting the second floor of the building. In each tie beam there are floor joist pockets cut into the tie beam. I made my pockets to fully house the floor joists at two inches deep. These are very simple joints to cut and they go fairly quickly.
Step 4: Cutting the Brace Mortise
Finally the last joint of this tie beam. A large part of the strength in a timber frame comes from the knee braces in the frame. These braces are what will fight any racking you will have from the wind battering your building as well as the weight loads that may shift the frame. These mortises need to be laid out properly and they need to be cut accurately.
As with all of the mortises in your frame you want to cut them a little deeper than the length of the tenon that will be going into the mortise. If the tenon bottoms out then as the timber shrinks over time the joints will push apart.
Step 5: In Conclusion
So we now have a tie beam that is ready to go into the frame. I often get questions from viewers and I am now starting to answer those questions on dedicated videos. If you have any questions you would like answers to or just a better explanation of what I am doing, then please feel free to ask away. I would like to start putting up Q and A videos every few weeks.
With that said, I hope you have found good information here and we will keep them coming.
Jim the Tradesman