Another small milestone. Just two more logs so far, but wow, it was not easy.
RPSL’s are Ridge Pole Support Logs- their job is to hold up the Ridge Pole (RP)- the largest, longest, straightest, heaviest log in the entire build. They are very important logs, and must have no defects and be very straight. I estimate the Ridge Pole I’m going to use to be about 5 tons (for comparison, the heaviest wall log was around 3 tons). Vertical compression strength for a 12″ log averages around 650,000 lbs (about 325 tons), whereas the horizontal strength of a 12″ log averages around 20,000 lbs (about 10 tons) over a certain span. Sorry for all the math, but what this means is you can have very skinny looking RPSL’s, and they will still be strong enough for any RP.
For a 40×40, the three RPSL’s are installed on three specially sized piers- 2 RPSL’s at the walls, and one in the middle. Before I poured the concrete, the inspector came out and he didn’t like the pier size specified in the plans. He wanted them one foot deeper in the ground (meaning one foot taller). He also wanted the RPSL to stand completely on the pier with no overhang. I did one better- I made them 5.5′ square on the base, and 5.5′ tall, and almost 20″ of support for the RPSL. They are about 2 feet in the ground. I estimate the roof at about 80,000 lbs. The piers on the plans should hold about 50,000 lbs each. I estimate my beefy upgraded piers at about 70,000 lbs each.
We looked at all the logs we had left and didn’t like what we saw. Julie wanted me to cut some new logs for RPSL’s. She found a reasonably straight tree, but when I cut it down, it had an awful (awful for an RPSL, but really good for a wall log) bend in it. After looking at it over and over, we decided to use it anyway. I found another tree for the second RPSL and cut it down as well. We will put the third RPSL up after the RP is installed. I was able to cut each RPSL and peel it in one night.
It went well, except when I tried to turn one of them with my ‘can’ hook- stupid thing was so slippery from being freshly peeled that it slipped when I was turning it- it sprung back to its resting position, catching the arm of my can hook, and slammed it into my collar bone, instantly dropping me to the ground. I laid there in a daze for a few minutes before I was able to move. When I thought I could move, I felt my collarbone, thinking I broke it, but it didn’t appear to be broken. But the pain was so intense, I was light headed and thought I might lose my cookies. Luckily, I recovered enough to drive home, and was back to work the next day- but with an awful looking bruise.
Installing the RPSL’s on a 40×40 is interesting- since we are building a two-story home, the top of the wall is 20′, and our roof pitch makes the final height of the RPSL about 30′. You can easily slide a 30′ RPSL under the house, and then stand it up on the inside. I hung a pulley from the wall at 20′, and proceeded to lift the RPSL into place. But the darn thing was top-heavy somehow, and I found I needed two additional pulleys to stop it from spinning like a propeller.
Another thing was the rebar coming up out of the pier that attaches to the RPSL was in the wrong place. It was a guessing game from the beginning: The 3 oversized piers have double duty- the two on the perimeter hold up the wall logs and also hold the RPSL’s. The one in the middle holds an RPSL and a girder support log (for the second floor support). Unless you use logs that are uniform in size (like telephone poles I guess), there’s no way you can know ahead of time where the center of the RPSL will be, and so you can’t know where to place the rebar into the pier when you pour the concrete.
The solution was:
- Cut the rebar off from the pier
- set the RPSL in place temporarily onto the pier
- measure where the RPSL will sit (you want it exactly perpendicular to the wall, plumb, and as close to the wall logs as you can get
- lifting the RPSL back up off the pier
- drilling a hole in the pier with a hammer drill
- squeeze the structural epoxy into the hole
- put a stick of rebar in the hole so that 12″ sticks out the top, wait 5 minutes for it to set up
- drill a hole in the bottom center of the RPSL where you marked it in step 3
- re-install RPSL onto the rebar
- re-check that RPSL is centered and plumb and lines up with the other RPSL
- check again just to be sure
- bolt RPSL to wall on every other wall log
Since our wall logs are so tapered and crooked, the RPSL doesn’t butt up against the wall next to every log. So instead of settling for the ugly look of all-thread between the RPSL and the wall logs, another nice idea from the LHBA forum was to install black pipe in between the gaps, giving it a nice uniform look. It was not easy, but it was worth it. I may counter sink the nuts and washers and put nice plugs over the holes, but I can do that any time.
Drilling a 5/8″ hole through a 24″ log, and then onto another 20″ log presents another challenge- I needed a longer bit- like 48″ long at the minimum. I went to the orange box people – $75 for one of those! wow! I went down the regular drill bit aisle and found a short one for $12. Then I went over to the neighbor’s and welded a 4′ stick of rebar to the drill bit. I ground down the chuck end so it would fit in my 1/2″ drill. It worked very well- just had to back it out of the hole 20 times (flutes were too short to get the shavings all the way out). No matter, it wasn’t too bad, and went pretty quick- after I got my scaffolding in place.
Yeah- scaffolding. Even though I don’t have temporary flooring in place and moving the scaffolding right now is a pain, the ladder is just dangerous for trying to drill horizontal holes – it’s usually too far away, or too close because of the angle of the ladder. The 13 amp drill I use can break your wrist if you don’t hold it right. Scaffolding will be invaluable when we get to chinking and a thousand other tasks coming up. And I got the scaffolding from California for about $600, including shipping. I love Craigslist.
I was going to go right onto getting the RP installed, but from what I’ve discovered, I should get my rafters ready before I call the crane. Yes, I’m calling in the big boys. I wanted to do this all myself, but a couple of realities have surfaced in my mind:
#1: I don’t want to die installing a 5 ton log 30′ in the air, balancing it on 2 RPSL’s. This is seriously heavy stuff. Yes, the wall logs were heavy, but not this heavy. Lots of things could go wrong.
#2: I would have to spend $260 on 2 chain hoists (I need some 5 ton hoists for the RP), plus $160 on 2 new 13,000 lb chains. That’s over $400. The crane guys say $130/hr, 4 hour minimum. That’s just over $500. I think my life is worth at least $100.
#3: I can probably get the RP and all 28 rafters installed with a crane in about 4 hours. If I do it myself, I figure a couple weeks getting the RP supports in place, and about a month to get the rafters up. Saves me a month of work, for just a little extra $$$.
We are nearly out of trees that are straight enough for rafters, so I talked to one of my neighbors- she’s letting me have probably a dozen more trees from her 5 acres for my rafters, if I bring her a plate of stuffed lasagna shells my wife made. I think there are probably a dozen (trees, not stuffed lasagna shells- stay with me) on my property, and probably about half a dozen on the next door property. I just have to cut them, move them, rack them, and then mill them into 4×12’s (work= yes, but I don’t have to peel them – yay!).
Stay tuned. I’m sure there will be a video of a crane and a 5-ton log flying over my house in the near future….