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.


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.


Our model

all you need is some grocery store bags, hot glue, and one of my knitting needles to make paper logs…

How we made our model

We made a model of our future log home out of strips of brown paper bag rolled into “tapered logs”. We had talked about it since I took the class. They actually recommend it during the class, and I had been pushing my wife to let me create one, but dowels are $2.50 for a four foot length, and we’d need about 15-20 of them for just the walls, plus some for the rafters, so $60 for a model didn’t seem practical. Loghousenut even mentioned it in a comment to me- people are willing to spend big $$$$$ for a model, then complain that they don’t have the money to get started on the real one.

The other problem with dowels is they don’t have any taper, so it wouldn’t really represent our build- other than the dowels are round.

I thought we could just save some branches from cutting trees and use those, and Julie spent some time one Saturday trying to round up some that were the correct size, but it’s very time consuming to find branches that are to scale, and they still don’t have as much taper as our logs.

Our very tapered logs and the fact that we haven’t seen any actual log homes built with logs with as much taper as our logs seem to have spurred us to build a model to see how things would look. We ended up spending $4 on the thick foam-poster board. $2 for “stirring sticks” that are our 2×12 beams. The “logs” were free (made out of long strips cut from paper grocery bags)…. Construction paper- $2 for a pack of it. The glue- I don’t know- got it at the thrift store. Had to buy a new glue gun- I think Julie said that was $2.50. Also, some cardboard for the roof cut from cereal boxes, and toothpicks for the handrails.

Benefits of a model

We learned a BUNCH working on the model – in fact, I couldn’t believe how much we learned:

  • The clockwise/counter-clockwise “pinwheel” arrangement of the log layers (LHBA people know what I’m talking about) was pretty confusing at first, but the model helped sort it out. Just gotta remember the pattern when building with real logs.
  • Everything is pretty much to scale. Each square on the graph paper represents 1 foot. the walls are a little off scale- they come out at 9 inches thick instead of the usual 6 inches, but it’s still pretty close. Even the logs are to scale (as much as possible). It really gives us a realistic view of what 24 inch logs that taper down to 8 inches will look like. Adding how crooked the logs were wasn’t feasible in the model, so we have yet to decide how that will look.
  • For me, I think that a 40×40 log home looks a lot better with bigger logs- the massive logs offset the massive home, making it look not so big. Julie thinks straight, uniform logs would look better.
  • We can now play with where the stairs are, and how steep they are. I forgot that the floor joists for the second level adds at least a foot to the stair height, so when we build for real, I’ll have to be careful.
  • Ceiling height- 10 feet? 9 feet? 8 feet? I like nice tall ceilings (helps with dissipating heat), but that means more logs. I think we’ve settled on 9 feet on the first floor, and maybe 8 feet on the second level. We might even have enough space for a little third floor storage area.
  • The woodburning stove is going to be an awesome appliance- and Julie’s idea for the location is perfect- it’s sort-of central in the living area, so it will efficiently warm the house. It’s close enough to the center of the roof that we won’t have to extend the smokestack 10 feet in the air- which would look stupid, I think.

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  • The girder support log might be hidden from view by the framed walls- I don’t know yet, but it’s something we have to think about when we build.
  • You can’t see the back doors or bedroom doors from the front door (which we like). It also gives us a great idea of what the place will look like – how the kitchen looks from the living room and how the living room looks from the bedrooms or the balcony. It’s just neat seeing what we are heading towards when we finish.
  • I can’t emphasize how much insight we are gaining by building a model- how high should the walls be on each floor? How steep should the stairs be? How much overhang do we want on the balcony? Does this angle work? How much headroom will we have in this part? Can we move this wall slightly?  It is very, very revealing when you have a model to work from.

Problems / Solutions

We ended up redesigning the second floor several times. We also moved some walls on the first floor a little to make room for HVAC and plumbing. We noticed the massive model logs are actually encroaching on the interior floor space. I got out the plans and looked- and the 40×40 stock plan is measuring 40 feet from the center of the wall log to the center of the opposite wall log. I was thinking outside to outside was 40 feet, so this actually adds a foot to our interior floor plan that we desperately need.

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We also haven’t completely settled on how to finish the second floor.  At first, we thought, just extend the walls of the bedrooms all the way to the roof, but that would make the ceiling in the center room almost 20 feet tall, and possibly hard to heat or cool. So there’s enough room above the bedrooms for a third floor loft / storage in the center area under the roof. We could just “cap” the bedrooms with a ceiling, and then use the space as a loft / storage. But to access it, we would need some stairs- we’re not sure where to put them- maybe next to the bathroom. But this is something we can decide later.

If we do have a third floor, there are all kinds of options- maybe we hang the third floor joists out over the second floor hallway.

T&G roof- the insulation is above the wood. Pretty!

Maybe we have the walls go up to the roof, or maybe it’s open with just a rail. Tons of possibilities. With this style of building, the insulation that is normally in the attic in a “stick built”home (what log home builders like to call a home built with 2×4 framing), is actually in the roof. So all you see from inside the house looking up is tongue and groove woodwork (T&G).

Here are some early photos of our model:

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Some interior views after we added the rails (we can almost imagine ourselves inside…):

For more photos of the model, see this post: stuck in the mud