Leveling Rafters

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Seems like there’s always more to do…

A few weeks ago, we took a major step forward- we are done with the walls, and we got the Ridge Pole and rafters installed. I’ve spent that past 2 weeks- in between weather events and life- getting the rafters level.

Again, if we were building with 2×4’s, it’d be easy. Building with crooked logs involves a lot of finesse and finagling to get things to look right. There is nowhere to ‘zero’ my measurements, so I have to do relative measurements. For example, the cap logs are actual logs, so they vary and wave as they go along the house, which means the rafters will do the same. The rafters, as I’ve mentioned, vary as well- but they at least have one flat side.

If I don’t ‘square things up’, I’ll end up with a crooked roof. That’s what is eating up my time. And leveling and squaring the rafters is done in 3 parts: setting them at 4′ on center, then leveling at the Ridge Pole, then leveling at the cap logs.

Setting at 48″ on center

When the crane guy was on site, we were paying him a bunch of money per hour, so we decided to just get the rafters close to where we wanted. Later, I went back with a tape and measured 48 inches from front to back, and placed the rafters on this mark. Then I did the same at the cap logs. When matching up the cap log placement of the rafters with the Ridge Pole placement, I found that eyeballing it was better than trying to drop a plumb line and squaring it up that way.

leveling at Ridge Pole

This was more complicated than I thought it would be. There are quite a few variables- roof pitch, Ridge Pole taper, ridge pole bow, rafter size, bolt hole placement, and not to mention working 30’+ up in the air. Dropping tools from that height is a pain. I ended up rigging up a pulley system and buckets and strings tied to the tools and then secured to the rafters. Yes, I wore my fall harness, which was a pain, but would have been more painful to fall.

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How far off level are the rafters from each other? Each letter represents a rafter pair. The top line represents how far from vertical they are. The center measurements (marked “E”ast or “W”est) show how off-center they are horizontally. The bottom line represents how deep to cut to overcome these issues.

The goal here was to get them level vertically as well as horizontally. Since the RP is so wide and has a slight bow towards the East, some grooves had to be made in the RP to drop the rafter pairs down to the correct height, and at the same time move it left or right to line up with the other rafter pairs. Cutting  a groove to move the rafter left or right also drops it at the same time. I measured several of them carefully, taking note of the exact placement and diameter of the RP at that point. I used graph paper to virtually drop a few of them a few inches to see what the effect would be before I cut. Once I was comfortable with my graph, I started in on the actual rafters. I used an electric chainsaw (much lighter and easier to maneuver at 30 feet up), and then smoothed the cut with an angle grinder and a rotoclip disc.

They are now all within 1/2″ of level and center.

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Leveling at Cap logs

I first took a string and a string level and nailed it to the rafters on each end. Then I measured the difference between the height of the string and where it touched the rafters and recorded it in a notebook. The rafter that is furthest away from the string is the lowest, so the next step is to make all the other ones match. Unless they vary by a lot. In my case, the East side of the house varied by 8 inches across the rafters- because it kind of sags in the middle. We knew the m when we put the cap log up, but we didn’t know it was 8 freaking inches. All four corners of the house are within an inch, but it’s the ends and the middle that matters, and that’s where the difference was. There was no way I could cut 8 inches out of a 13 inch cap log- that would weaken it beyond use.

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To overcome this gap, I jacked up the most offending rafters and installed two 4″x5″x14′ beams that I made on the sawmill and pinned them with rebar. This won’t be seen when the roof is on unless you know where to look because there are other boards called bird blocks that go exactly on top of the beams.

On the west side, I overcame the issue much easier with a 2×4. The rafters rest on these “jacks”, but they are still pinned with rebar through the jacks and into the cap logs.

They are now all level to within 1/2″ of each other.

 

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Next steps

Before we can install the decking on the roof, we need to install our girder log. This log acts as a ‘collar-tie’ for those in the industry. For non-industry types, the girder log keeps the walls from spreading when the 80,000 lb roof is installed. The girder also holds up the second floor. It can be installed at anytime, once the wall logs reach over the second floor. Those using telehandlers usually install it right when the wall logs reach second floor height. When using ropes and pulleys, it’s easier to wait until the wall logs are done so you have somewhere to hang the pulleys.

2 thoughts on “Leveling Rafters

  1. Hi mudflap. We are in trailing you by a bit with our build and are hoping to make some progress soon by installing RPSLs, RP, rafters, etc. I noticed you went to great lengths to notch your RP for the sake of leveling the rafters. I understand how to level the RP and also that the RP width differential from each end may make the rafters flare a bit. (I’m not an engineer, but it appears this way). I don’t hear much talk about notching the RP from many builders. I understand you may have had a unique circumstance, but my wife and I are a bit concerned about whether NOT notching the RP will result in a noticeable flare. I’ve considered whether lowering my large RP end a bit more than needed for a level top in order to compensate a bit for the flare that may result. In short, is notching common? I would appreciate your opinion. thanks for any help.

    Liked by 1 person

    1. Hi Chris –
      Yes, I think notching the RP is common if you have one that tapers or bows like we did (33″ butt, 16″ tip, over 65′). Ideally, there will be very little taper, and very little bow, and this will be because you picked the largest, straightest log for your ridge pole. But every log has some tapering. And yes, I think you’ll notice (but nobody else will). What I did to compensate for the difference between the butt and the tip was make the RPSL’s match that height. For example: if you measure the diameter of the RP where you think it will sit on the RPSL and find 33″ on one end, and 16″ on the other, you would do: 33″ – 16″ = 17″. So then make the RPSL on the butt end 17″ shorter than the RPSL on the tip end, then the top of the RPSL will be more or less level between the RPSL’s. What I failed to realize was that a string level is only accurate up to about 20-30 feet. After that it will sag in the middle, no matter how tight you pull it. I can see this slight dip in my roof. It’s probably off by 1″ – 2″ over 65′. Not structural or anything, but I don’t like it. It’s not something you can go back and fix later. Little things like that bother me, but I also did the best (which is pretty good for a first timer) I could at the time. I tried to notch it to compensate for vertical displacement (humps and bumps in the RP), as well as horizontal displacement (flare).

      If I were to do it over again, I would use a water level instead of a string level to find the low point among my rafters, and then get all of the rafters the exact same height. The flare might not matter as much for a shingled roof, but might for a metal roof.

      It is pretty scary using a chain saw up there while dangling on your RP. I also used a roto-clip disc to cut the notches.

      Like

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