Floor joists: step by step

In a previous post I discussed my ideas about how to cut a dovetail tenon and the arc I planned for the floor joists. At that point in time, all I had done was to try out my ideas with the portable band saw. Last Wednesday, August 15, Mark the Intern and I began putting my ideas into action on the floor joists. The frame has 33 first floor joists, 26 second floor joists, and 37 purlins. All of these are cut from 12 foot oak 4"x6"s. We started with the first floor joists since these wouldn't be seen. This gave us 33 to practice on. As I've mentioned earlier, we are only going to have one end completed before the raising. Once the frame is up, we can measure to make sure that the floor joists and purlins are the correct length. Some beams and rafters have a little bow to them and all the timbers' actual measurements don't correspond exactly with their nominal measurements.

Here are the steps we took for cutting the dovetail tenons and decorative arches on the joists and purlins:

First, we have the 4"x6"s in the garage on the saw horses. We worked with four at a time because this amount gave us enough room to move them around and work on them.

For the second-floor joists and the purlins, we planed the visible surfaces. We were able to run the two vertical sides through my 12" Powermatic planer, but because it can plane a 5" maximum thickness, we had to plane the bottom of each by hand. We didn't plane the first-floor joists because they won't be visible from inside the house. (Yes, that's me in the picture.)

After planing the joists/purlins, we marked and cut one end square. The other end will be cut square at the time it is finished. The next step was to mark the dovetail and the arc on the end using the templates I had previously made.

Once the end was marked, we cut the bottom of the tenon with the circular saw. We also cut across the bottom of the joist on the line next to the arc.

After making these two cuts with the circular saw, we knocked out the square at the bottom of the joist along the underside of the tenon and in front of the arc. The portable band saw doesn't have a deep enough throat to cut the arc without removing this block of wood.

Using the portable band saw, we next cut the arc. It's quite easy to cut this crooked until you get a feel for the saw as one side or the other cuts higher, lower, faster, or slower than the other side. It wasn't critical on the first-floor joists since they won't be seen. So, that gave us 33 to practice on.

After cutting the arc, we used the circular saw to cut the shoulders of the dovetail to the correct depth, and then we used the band saw to cut the angle from the corner to the shoulder.

After completing all these steps several times, we had a stack of floor joists ready for raising day.

Update: 9 days until the raising!

The hot and humid weather has continued all month. We haven't had any rain in August and we've been over 90 degrees every day so far. Yet, we've continued our work in preparation for raising day.

We completed the assembly of the final bent on Tuesday, August 14. We then began on floor joists. For them we're cutting the dovetail tenon and decorative arc on one end. The other end will be completed after exact measurements are taken once the frame is erected. We finished all of the floor joists (59 total) and the purlins (37 total) on Thursday, August 23 (yesterday). We also built the gin pole on Wednesday of this week. It's about 16' tall with a 7' base. I still want to do a bit more with it early next week before getting it put into place.

When doing the fit-up and assembly, a tenon on one collar tie broke. So, I needed to replace that. I completed that replacement yesterday, also.

So, at this point, the frame is ready to be raised! It's kind of amazing to have all the timbers ready. It's taken a full 2.5 years to get all the joinery and fitting-up done. I'm not complaining. I really haven't worked on it continuously throughout that time. There were some weeks and months when I didn't complete any of the joinery because there were other things that needed done.

I'm looking forward to seeing the frame standing in place. I'm not sure what all I will feel when it's up, but I imagine there will be several emotions. It's gonna be great, though!

Bents 2 and 3 assembled

It's been hot here -- mid to upper 90s with plenty of humidity. Still, there is work to be done. So, I've been doing a lot of sweating. The 90 degree temps are forecast to continue for a while yet.

Mark and I have worked on the frame in between harvesting and preserving the produce from the garden. This week, because of the heat, we've begun work around 8:00am after chores and breakfast. We generally return to the house for lunch and to appreciate the air conditioning, as limited as it is with small window units, around 1:00pm. The prospect of returning to work and sweating some more in the heat after lunch is not one we gladly welcome. So, we are happy to find things to do inside during the afternoon.

We were able to finish assembling the second bent last week. Actually, it's Bent 3, but we started with Bent 4. It's the second one we've assembled. We worked this week and were able to get Bent 2 put together, too. So, that's three bents assembled. One more to go -- Bent 1. God willing, we'll complete that one next week.

I didn't take any pictures of our third bent assembly as we worked on it this week or after finishing it today. I do have some photos of Bent 3 we completed last week (the second one to be assembled). I'll share several now.

The first photo details an error I made in laying out the intersection of the rafters for Bent 3. There are two pitches on the roof: 8:12 on the front and 3:12 on the back. I tried to be as careful as possible in the laying out, but I get the angle wrong where the two come together. You can see the gap that exists in the photo. I'm not going to cut a new rafter, mainly because I don't have another 16' 6x8 lying around. I also don't believe it is necessary, and I don't want to go to all the trouble to cut the joints. I will cut some wedges to fill in the gaps so that my error will not be so readily visible. I will also drive a wedge in on top of the tenon to fill in the gap that exists on that side. I wasn't pleased upon discovering this error, but it will be alright.

The ends of the collar tie where it joins the rafter were cut correctly, though. The photo on the left shows the collar tie on the 3:12 pitch rafter. This intersection is a long one, but it came together nicely. The other side also fit tightly. You can ignore the unsightly gap at the peak!

The process of assembling the bents involves first fitting together the rafters. Then, we put the rafters away and begin putting together the posts and beams. The rafter sets will be assembled at the second floor level and raised there on the day of the raising. The photo to the left shows the beginning of the assembly of the main portion of Bent 3. We set the posts into position and have the scarfed tied beams laid out at the top near where they will fit. At this point, we check to make sure all of the braces will fit and that the mortises and tenons for the beams are correct. I also drill the holes for the pegs through the mortises. When we fit the tenons in their corresponding mortises, I mark them with the point of the auger bit (running the drill in reverse). After pulling the tenon out of the mortise, I drill the hole in the tenon closer to the shoulder of the joint than marked. This is so that when the peg is driven through the tenon in the mortise, it will draw it tight. This technique is known as draw boring. For some joints that fit tightly and are pulled together well, I don't draw bore, mainly because I don't want to have to pull the pieces back apart.

The photo to the right shows the bent after we've fit the first floor level beams into their mortises on the posts. We fit these and peg them. Then, we put the braces in the posts and pull the tie beam into place on its tenons. There is a 2x6 tenon that goes through the scarf joint on the top of the center post. This tenon goes all the way through both sides of the scarf joint.

The three photos below show each of the joints where the first floor beams connect to the posts.

Next, here are three pictures showing the connection of the tie beam to the posts.



In the photo of the scarf joint above, you can see another error at the top of the brace on the right side. Somehow when I cut the joints on this beam 2.5 years ago, I measure wrong and put the brace mortise 1.75" too far out. I had to extend the mortise towards the post so that the brace would fit. I'll plug the hole with a 2"x1.75" block of oak later.

Here's a photo of the first two bents we assembled, or at least parts of them. After we were finished, I snapped a photo of Mark the Intern resting on the timber pile. We have the girts, rafter sets, braces, and unassembled posts organized at one end of the work area. Of course, after assembling three bents (only two were assembled at the time of this photo), the pile is diminishing, at least parts of it.

And, finally, a picture of the first two bents after assembly. If I had a picture of all three, I would post it. Hopefully, I'll be able to post a photo of all four assembled bents next week.