Bird Blocks and replacing a wall log

Just finishing up some minor details before I start the roof…

Bird Blocks

Since the rafters sit on top of the wall, and the roof sits on top of the rafters, there is a gap between the top of the wall and the bottom of the roof- the space between the rafters. This space in between the rafters has to be filled in with “bird blocks” to make the home weatherproof. There is some discussion on when to place the bird blocking- before adding the roof or after? I thought it would be easier to add it before, since it would be hard to fit the bird blocking in the space when the space is completely surrounded by rafters, walls and a roof, so I spent some time custom fitting some boards in between the rafters.

45637853912_7884180b97_k

I used the sawmill to turn some scrap logs into 2×14’s, since the rafters are on an angle, and I wanted the bird blocking vertical. Then I toenailed each board into place. It didn’t take long- just a few days working at night.

The time changed while this was going on, so I bought some worklights and strapped them to the middle RPSL so I could keep working after dark. The cabin looks really cool all lit up at night.

45714296842_bc3248ee62_k

Replacing a wall log

When we placed the girder log in the wall, it ended up resting on a wall log that I’ve been worried about from the time we installed it. I knew this log was “not perfect” when I installed it, but we were in a hurry, and didn’t think we had enough logs to finish the walls at the time. If you notice a log that goes “thud, thud” instead of “thunk, thunk” when hit with a hammer, this is usually an indication of rot. I’m not sure how it happened to this particular log, but since the girder log was going to rest directly on it, I thought it was prudent to replace it before I let the girder settle on it. I checked all the other logs just to be sure and they all seem to be Ok.

It turned out to be a huge pain in the rear to replace. But this is the neat thing about a Butt & Pass log home: the rebar that ties each log to the log below it also ties each log to the log above it. This means you can (if you’re nuts), cut out a log you don’t like right in the middle of the house, and it won’t fall down. Try doing that with a kit log home. Actually, no, don’t try it.

I used the “saws-all” tool with a metal cutting blade and cut the rebar out in four foot sections, then used the chainsaw to cut the log where I had cut out the rebar- I didn’t want the whole log falling out at the same time. At four feet long, the cut sections still weigh a couple hundred pounds each, so it was a little scary.

45232341434_03b3191d94_k
Logs look weird suspended like this

Anyway, although you can do this, it is really difficult to replace a log because you have to find one that fits exactly – same taper, same size, everything. Since that’s hard with the crooked logs we used, I had to do the best I could- I found one slightly larger- by about an inch, and dragged it over to the gap I created by removing the rotten log. I used the chain hoist and a pulley to lift it carefully into place, and then started cutting knots and bumps out of the neighboring logs as well as the new log to fit it into place.

45232342684_d0e297fa34_k
using chain hoist to install new log

It took me a week, working a couple hours at a time at night to get it into place. The rebar had to be installed at a slight angle since there was already logs in place around it. I think it will be fine- we’ll chink over those parts, and it will look fine. It was a sigh of relief to know that the rotten log is gone, and the new one is solid.

45915582621_a0c4f891a8_k
See the new log? It’s the one that sticks out on the end…

Next up, I get the Tongue & Groove 2″ x 6″ “car decking” installed, which is part one of getting the roof on.

Girder Log & Girder Support Log

 

I estimate the roof of my log home will weigh around 50,000 lbs. In class, they taught us that you need a girder log that is crosswise to the ridge pole to increase the strength of the structure. The girder log is also known as a collar tie. Its job is to keep the walls from spreading apart due to the weight of the roof, as well as to support the second floor.

Since we used pulleys, we knew we could install the girder log at any time after we reached second floor height. We decided to wait until now.

Height of girder log

I was stuck, though, at how high to set the girder log. Our walls are almost exactly 18 feet high. Minus one foot for the first floor and another foot for the second floor gives us eight feet for each floor. But were we supposed to put the bottom or the top of the girder log at eight feet?

I ended up calling my friend and fellow LHBA member Ivan to see what he thought. He said building code specified 6 feet 8 inches for head space: as in, don’t set the girder log any lower than 6′ 8″ from the finished floor height. That was the perfect starting point. So I added a foot to that for the finished floor height (7′ 8″), and then rounded up to 8′ and placed a mark on the wall at that height.  We decided the fat end of the girder log would go over the kitchen, since on that end of the house, the girder log holds up the bedroom areas as well as the bathroom and other rooms. The other end is open to the living area, so it only needs half the joists.

Installing the girder log

Installing the girder log with pulleys is fairly straightforward: get the girder log next to the house, cut a hole in the house, attach a pulley and lift until the log is in or near the hole in the wall. Attach a second pulley through the hole and pull the log into the house. Continue to adjust pulleys and lift / pull until log reaches other side of the house. Level the log, cut another hole, and pull it through. Then pin it with rebar.  Make sure it is raining – you don’t want to have too much fun. 🙂

As usual, my wife was a huge help. I pulled on one pulley with the tractor, while she let me tie the other pulley to her car. My daughter watched my hand signals from inside the car and relayed them to her mom. We are at level “pulley ninjas” at this point in the game.

 

This slideshow requires JavaScript.

Installing the Girder support log (GSL)

On smaller log homes, an angle bracket can be made to support the girder log. The bracket is bolted to the middle RPSL, and the girder log rests on the bracket. On a 40×40 log home, the span is at least 20 feet between supports, so a girder support log (GSL) is required. The GSL is not hard to find- it only has to be about eight feet long. We pulled it from a scrap log we had, and picked it so it has no knots and very little bow. I dragged it with the tractor (yes, it still weighs about 500 pounds) over to the house, then used the pulleys to drag it inside.

45704856622_98ccdd4d77_k

I knew the girder log sagged a bit in the middle by about two inches (because the string level told me so!), so I measured the space between the pier and the girder and added two inches. After doing a test fit, I cut the GSL to the right length, drilled a hole in the bottom for the rebar from the pier, and then lifted it as close as I could to the girder log, which was still sagging. I chained it in place and moved the chain hoist to the girder log and lifted the sag out of it. With the sag out of the girder, I was able to just push the GSL by hand into position. Using my favorite tool (can(t) hook), I rotated the GSL into position, then lowered the girder onto it and drove a pin through the girder to keep it from slipping. Later, I’ll install 1″ all thread and bolt the GSL to the girder. This puppy ain’t going nowhere.

This slideshow requires JavaScript.

Next steps

We install the bird blocking, which fills in the space between the rafters and the walls.  I’m calling around to get the best deal I can find on 2″ x 6″ tongue and groove car decking (which is the “hardwood floor” you see when looking up at the roof from the inside), but not having much luck finding a good deal. It looks like it will cost me about $7,000 just for this part of the roof. Still need to get the underlayment, the 2×12 sleepers for the built up roof, the insulation, plywood, and shingles or metal roof (if we can afford it).  The roof really will be the single most expensive part of this build. On the other hand, I can’t wait to have the whole thing dried in.

 

Leveling Rafters

31672501728_d194f21eae_k

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.

45201877451_09a2dc6192_k
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.

45213384871_3e666c834a_k

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.

This slideshow requires JavaScript.

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.

 

This slideshow requires JavaScript.

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.