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.

 

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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.

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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.

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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.

 

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Cap Logs Installed!

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Our cap logs are installed- this means we are almost ready to enter a new phase of construction. It has been a long hard road. Some folks at LHBA claim we are moving at “one gear below breakneck speed” using our lifting poles, but it often doesn’t feel that way…

What are cap logs?

Cap logs are the final logs on the walls. In the photo above, they are the ones that stick way out on the front of the house. Paired with ‘double-butt logs’, they hold up the roof rafters, and give the roof enough overhang to protect the wall logs from rain. In a kit log home, they usually don’t stick out much, but for a butt & pass log home – with an expected lifespan of 350 – 450 years – they are a major part of that lifespan.

Notes on installation

Our plans are for a 40’x40′ cabin. The overhangs on the roof protrude out 7 feet past the walls on the gable ends, and about 4 feet out on the eave side. This means the cap logs have to be 7’+7’+40′ = 54′ long. Also, they need to hold up the roof rafters, so my goal was to make sure they were 12 inches minimum on both ends. With our tapered logs – this meant that the butt end would have to be absolutely huge to ensure at least 12 inches at the tip. This would also throw off our level layers (all 4 corners should be the same height).

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The solution I came up with was to take two normal sized logs, splice them together and put them up as one log together, and let the butts hang out over the ends.

Easier said than done. How do you lift half of a log when the lifting poles are in the corners? In other words, how do you hold up a log in the middle of the house where there are no lifting poles? Easy (not easy)- you chain both together and lift them at the same time.

Although I could have (maybe) installed a temporary center lifting pole- this would take a lot of energy and time- I would basically need a 30′ lifting pole (the size of an RPSL) installed. It would need to be chained to the wall, along with pulleys, etc. Lots of work for something I would use once. So I decided to try everything else before this idea.

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Using a cradle (suggested by Plumb Level), we were able to “safely” hold the logs in place while we pinned them. I won’t go into the details (unless someone is dying to know), but there were a lot of scary moments- like once I got the chained logs in place, I had to remove the unused portion of each log- this involves cutting the excess of the log, and hoping the desired portion just falls into place, with no way to chain it or support it until it was in place. The cradle helped a lot, but there were no guarantees.

Some unlucky (and funny) events from Course 13

First there was the “pinned boot” incident:

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There was a gap in the log I was working on. I was perched up on top pinning it into place, and my boot happened to be placed right where the pin was coming through. Once they go in, they don’t come out. It didn’t pinch my foot- just the edge of the boot- and tight enough that I couldn’t get my foot out. I was stuck. I called for Julie’s help. Now she is not normally one to climb ladders of any size, but she courageously started to climb. She was clinging to the ladder like she was a thousand feet off the ground. I kept encouraging her and she finally climbed up high enough to hand me my crowbar, and I was able to loosen the pin just enough to free my boot. LHBA folks suggested I just leave it there and chink around it, ha ha! ……No.

We had this log that was the right dimensions, but had a nasty hook in it at the tip. No matter how we rotated it, it wouldn’t lay flat. We decided to pin it anyway, and just deal with it later. It ended up being flat most of the way, until about 6′ from the end where it had this big bow in it. Since that corner (NE) has been historically low, we decided having the extra height in the corner would help get the height back up to where it needed to be. But since you can’t accurately measure the height on an odd row, we’d have to wait until layer 14 to find out if it was helping or not. And it is: before the cap logs, our heights worked out great- starting at the NE corner and going clockwise, we have 17’8″, 17’8″, 17’7″, 17’7″. For non-builder types- this means the East and West sides match each other exactly for height, while between the two sides, we are off by 1 inch. Remember- this is all using tapered crooked logs with knots and bends- a real testament to the Butt & Pass method.

And the burned out motor on the drill incident: It is a Black & Decker 1/2″ drill that didn’t really want to drill 300 holes, but it held up for the most part, and then just gave up with the drill bit lodged 12″ down in a log.  So I left it stuck up there; “sword in the stone”-like, for the weekend. I figured more power to the idiot who decides to try and steal it. There were no takers.

And five minutes later, the “what the heck happened to the jack hammer” problem: it just lost power in between pounding rebar. I took it home- I guess all the vibration and the weight on the cord from being up so high pulled its guts loose from the switch. I put a new clamp on the wire, taped it in place, and then put the handle back on. Then I taped the cord to the handle on the outside to alleviate some of the stress.

What’s next

The final height of our cap logs determines the final headroom height at the top of the stairs, since they are on the eave side of the house up against the wall. It works out to be (starting at the NE corner and going clockwise): 18′ 4 1/2″, 18’6″, 18′ 5 1/2″, 18′ 4 1/2″. Pretty good.

Now we finish with double-butt logs – these are not logs with 2 butts on them- they are logs that, instead of being normal “butt and pass” logs, are just logs that butt up against their neighbor logs on both ends. In this case, the logs they butt up against are the cap logs.

After that, we begin the next phase: installing the RPSL’s (Ridge Pole Support Logs). Two of these get bolted to the walls. Along with one in the middle. They are 30′ tall, and they hold up the Ridge Pole – which holds up the rafters and the roof.

The Ridge Pole is a monster sweet gum tree from our woods. It is by far the biggest heaviest longest and straightest log I’ve ever cut down. So far, it has evaded me being able to move it. But it won’t for long.

We also need to commit to a height for our girder log. This log spans the width of the house and holds up the 2nd floor. It also ties the East and West wall together so the rafters don’t push the house apart. It provides the “rigidness” that keeps the house tight. At least a little.

I don’t want to think too far, but I’m hoping we can get the roof on this summer.

We had a lovely visit from some LHBA members- Gary (Mosseyme) from East Tennessee came and looked one day in the rain and gave me a lot of good tips, and encouragement. Also, ‘Sdart’ on the LHBA forum- Sara and Rene were very nice and came out to see our progress. They are building in extreme Northern Idaho in an off grid location. They have been to many LHBA homes over the years all over the country and Sara told me, “even after looking at pictures, these homes are always impressive in person.”