Connect the Logs - Olylog, Lagbolt, Cable systems, Springs

[Dan Bodenstein]

I am familiar with Lagbolts and Olylogs, and I've head of the spring loaded method.

Tim, can you shed some light on the cable system you use?

We used Lagbolts on our home. We were told by a few people that lagbolts would be better than OlyLogs. Personally I looked at the Olylogs and they look like glorified drywall screws.

I know that lagbolts are more labor intensive, but sometimes you have to place cost over convenience.

I've head of the spring loaded connectors, but I'm not 100% on how they work.

Share the knowledge! :)

Dan

[Tim Bullock]

Dan, Lag Bolts would hold a lot better than Olylog simply because the thread cross section is larger. We make up our own cables with 3/16" S/S Cable, 3/8" threaded rod with an "eye" and splice the cable through the eye. The rod is longer at the bottom (under the subfloor) which allows for a 700 lb spring to fit over the eye and attached with a washer and a nut. As the building is reassembled we thread the cable through the predrilled holes all the way to the top and secure it at the top with another nut and washer. Simply tighten the cable at the bottom to put pressure on the logs and adjust as shrinkage occurs. We precut/splice the cable as we drill prior to taking apart the building....all pretty simple.

[Dan Bodenstein]

Tim,

You're right it sounds simple. So simple it doesn't make sense why others would not use it. Although, does it cause a problem while stacking the logs. In other words, it sounds like the logs are just sitting on top of each other while being stacked... no support until the last log is placed.

I'd love to see a drawing of this system. Do you have one you can post.

I am glad that I am not insane on the OlyLog issue. :)

Thanks for clearing that up!
Dan

[Tim Bullock]

Dan........It is simple actually.......If there was a tendency for the logs to roll in/out...temporary bracing could be used. Further, unlike thubolts, it is not necessary to be 100% accurate with the hole drilling. You can see through bolt blow-outs on Handcrafted Log Homes all of the time.........pretty hard to drill a 10' long hole.
No drawing program here at home........but it is really as simple as it sounds.........LOL.

[Kyle - Utah]

Hello Dan,

I noticed that you took an interest in the spring and cable method of securing logs. It is quick. It is easy, but is it the right thing to do? You need to ask yourself whether the purpose for doing this is to create a self-adjusting compression fit that adds safety and stability to your home or if the purpose is to just squeak by with the bare minimum that your local building codes require.

How about a couple of examples?

Take ten pencils and drill holes through them about an inch from each end. Then cut a couple of rubber bands and thread them through the holes. Tie big knots at the top and bottom so that they look like they are stacked logs. They hold together nicely and keep pressure near the areas where they are threaded through. The finished product creates a flimsy 'board' that acts like a slice of cheese unless the rubber bands are pulled very tightly.

Now take another ten pencils and pre-drill holes so that you can connect them together in stacks of three with small brads. Stagger the holes so that the third pencil in each group is included in the next group. This just gets confusing so assume that the 'n's in the following example are the nails and it should make a bit more sense:


.=====n==========n==========n======
.=====n====n=====n====n=====n======
.==========n==========n============
.=====n====n=====n====n=====n======
.=====n==========n==========n======
.=====n====n=====n====n=====n======
.==========n==========n============
.=====n====n=====n====n=====n======
.=====n==========n==========n======
.=====n==========n==========n======

If you pick this puppy up you have what amounts to a board.

In the first example you have a finished product that would appear to be more seismically sound. The only problem is that if you pull hard on any of the pencils the rubber band either snaps or pulls through the entire assembly. This leaves you with pencils flying everywhere.

In the second example you must imagine that the holes are actually larger in diameter than the rods that pass through them. This allows them to slip and move in the event of an earthquake. They still exert downward pressure to keep the logs snugly joined, but they are 'fluid' in the case of settling or in an earthquake.

You can have the best of both worlds here. It involves a product called "All-Thread." This is the stuff that looks like a threaded bolt without the hex top. It's just threaded rod. The beauty of this stuff is that it comes in lengths of up to 24'. This permits you to custom cut every 'bolt' so that it fits exactly. You use this stuff just like the example using the n's above, but with a slight twist. The bottom of the 'bolt' receives a nut and a washer as you might expect. The top gets a washer, a spring, another washer, and finally a nut. The nuts are secured using a product called LockTite, or better yet, tack-welded and using LockTite. (Tool discount centers usually sell small 110V 100Amp welders for under $75.) This prevents them from moving over time.

What you get looks something ike this:

#
----
@
@
----
==========

Log Here

==========

Log Here

==========

Log Here

==========
----
#

And now for the bad news. Doing things this way means that you will also need to back-drill the log that is going to sit on top of this assembly. This allows the spring and nut on top a place to live. Be sure to use a torque wrench when tightening the top nut so that each 'bolt' applies even pressure to your logs. The number of foot-pounds of pressure to apply will depend on the type of wood that you are building with. Amazingly enough, this pressure rating will likely be found in the building codes in your area, so you won't have to guess.

Speaking of building codes, be sure to check them before you decide on any construction method. The spring & cable thing does not meet the codes where I live, but your area may be different. If you're building a small mountain cabin then the codes will probably be a bit more relaxed than if you are building in a residential area. Still, what is your safety and the safety of your family really worth to you?

Best Regards

[MikeS]

"You can see through bolt blow-outs on Handcrafted Log Homes all of the time.........pretty hard to drill a 10' long hole."

No, if you do it the right way, it's easy to do. Drill the holes after the rough scribe, and prior to the final scribe. We use a leveling tool to transfer the hole to the top of the log being drilled, and drill with a drill that has a bubble level. Hits the hole below all the time. No blow outs because we scribe after the hole is drilled. Rod can be installed after the assembly is completed.

There is no absolute one way to do things right. It's if you don't solve the short falls of a system that it is wrong. Do you use springs, Tim? Highly recommended, from my experience.

[Rod]

Hi Everyone:
I'm new to this forum and must say that it is truly an invaluable source of information. I especially find this discussion of thru-bolts very interesting and have a quick, likely naive, question:

For full-scribe, handcrafted construction why are thru-bolts necessary, and where would they be located? I suspect that the answer to this is "beside door and window openings" but wouldn't the keyways and splines suffice for this?

Cheers,
Rod.

[Tim Bullock]

Mike, I do use the springs in the basement or crawlspace......Rod,
We use cables only when we have to conform to building codes....
I really dislike through bolts for the following reasons:
1. They are close to actual diameter of the hole and are prone to rust and condensation.
2. They are not nearly as strong as steel cable.
3. If the holes do not line up perfectly, this will affect the normal settling and could hang up the logs.

Mike is quite correct in that you can drill from log to log without the blowouts but can the total hole be plumb???

I have never liked the concept at all but the kit homes (log on log) had to do something to make their buildings stay together other than spikes...........Nuff said.

[MikeS]

Rod

I use through bolts plus springs because it improves the fit of the logs after settling. This is a long term benefit. In addition, since I also general contract, I have been aware of problems carpenters experience with overscribing techniques in log construction. I like overscribing, and use it. In the short term, through bolts allow adjustment, in order to plain out the top plates, so the roof is easy to frame and build. We'll use an impact wrench to drive the underscribed saddles tight, in preparation for the carpenters. This is not possible with cables or lag screws.

Some of Tim's comments about the problems of through bolts, like alignment, is an issue for one not experienced with their use. We have not found this to be a problem for us, and have used through bolts for 10 years or so. I'm not too concerned about the steel issue in logs, because we seal our logs such that the dew point is farther out in the laterals. We also do restoration, and steel is not the cause of rot in buildings we have worked on. We also encase our through bolts in plastic tubing, and use plated bolts. From my experience, the advantages far outweighs the disadvantages, if there are any disadvantages.

Location of through bolts is based on the builder experience and building methods. Near the corners of overscribed buildings is a minimum.

I would never build without some sort of fastener, especially for the top three courses minimum. We use so much insulation and packing, that our logs float during the assembly. The fasteners are essential to prepare the building for the carpenter, and plain it all out at the top plate and roof lines. Some sort of fastener is essential if you live in a high wind area, which is practically everywhere. What happens if a tornado goes over your log home?

There are many different ways to build. Each handcrafter, whether experienced or not, uses a list of components as part of their log work. Through bolts, cables, cutting methods, overscribing... all are components. The right combination gives good fitting log work, after drying and settling. There are several right combinations.

Look through my web site and read the "building methods" section, which goes over many of the handcrafted components used within the industry. It's a good summary for your education.

You won't be able to judge or choose a builder by whether or not they use through bolts, cables, pins, or any other fastener.

[Dan Bodenstein]

No one mentioned Elmers Glue.

Well at least I can see that lag bolts and OlyLogs are not an option.

I am concerned with the "slice of cheese" effect, as Kyle mentioned. It seems to hold water. But I assume thickness of the logs would also be a factor.

It looks like springs and thru bolts are the way to go. I'd still like to hear some more opinions on this and would love some drawings. (Crayon drawing are ok)

Thanks to everyone who shared the knowledge.

I'm still a ways off from building log home #2 in North Carolina. So I am doing the homework!

Thanks!
Dan

[Rod]

Tim, Mike: thanks for your informative and thought provoking replies.
Mike, I was surprised to hear that thru-bolts are used near the notches, as I had assumed that they are typically used for lateral support on log ends that are not notched. I'm assuming that this is to pre-compress the notches? I can understand how this would be beneficial to leveling the plate logs for framing.
You mentioned overscribing the laterals which brings to mind another question: during construction would you not end up with a significant gap between the header log and the log directly below at window and door openings? After settling, this gap would close, but how do you deal with it in the interim?

Cheers,
Rod.

[Kyle - Utah]

Well Put MikeS! :)

[BradBradstreet]

Mike, we have discussed this a bit on the olde version of this forum. There is another alternative that seems to work in some situations. We used long, round, chinked dry logs (they go from corner to corner & are saddle notched).

With this approach we have 1" galvanized pipes that are cut to a length of 15" used a pins in the logs - every 18" or so. Each pipe section goes through a log and half way through the one underneath. The logs are spiked with a 12" spike at the corner notches - I think more for positioning.

As the log is being put in place a pad of insulation is put at the notch - log is lowered into the final position. Then the 2 corners are spiked. Then the 15" pipes are pounded through the log and half way through the one below. While the crew is doing this activity the crane goes back for the next log off the truck and gets it in place. With enough of a crew this can be a smooth operation with no pauses. One semi-truck load of logs gets placed and pinned each day. Truck arrives early in the morning and leaves empty at the end of the day.

In our case the log supplier had marked on the logs where to place a small plywood spacer (or two). As long as it is not too windy they stay in place. On day #2 we had to put a few back in place. On day #3 we could not move any of the spacers as the logs had settled down on the pipes. These spacers were to stop the settling. As the logs expand and contract that movement is taken up by the chinking since it is elastic. We have not seen any issues from our "owners' perspective".

Maybe Mike can provide insight into this approach from a builder's viewpoint.

[BradBradstreet]

Alan, that is one way of saying it. The log supplier told us up front the ridgepole would settle about a foot between the time the logs were erected and when the first door or window opening was cut. By then the expectation was that settling would be "done". Certainly the major settling.

Where we have a sheetrock wall on the first floor (bathroom) that joins into the exterior log wall. One can see where there is a gap between the top of a log and where the paint was put on the sheetrock. This shows about 1/4 to 3/8" of settling since the wall was painted (at the end of the building process).

[MikeS]

"would you not end up with a significant gap between the header log?"

Rod, you are right. This is one of the reasons we use through bolts, and torque the logs down strongly and compress the notches. The through bolts near the corners do the majority of the compression. With overscribing technique, the notches in fact are UNDERscribed. Laterals overscribed, notches underscribed, depends on what your basis of comparison is. This method does result in much tighter notches, after settling. However, it does create construction problems that have to be addressed, including the issue of a space at the window header log. Initially, tightening through bolts addresses this issue immediately after logs are set, plus it plains out the plate logs so the gables and roof go on to a flat plain. The ability to continue to tighten them keeps the top courses tight after settling and resists high wind uplift.

This is why techniques and components of differing log builders will be different. I would not use cables in conjunction with my fabrication techniques, undersribing for example. Bolts fit the bill much better.

20 years of experience is what this and all the other stuff we do is all about. It's the reason many customers hire log builders like me and Tim and other experienced log builders. (I had to include Tim in this, because he is buying me a beer soon, see "partay" thread.)

Brad; The logs in a chinked building are tied together structurally 1) at the corner notches, and 2) at the window/door splines. This is inadequate alone, consequently the addition of pipes and spikes. Your pipes and spikes, which are pounded in, not slipped in, are 1) reducing settling of the building and 2) stabilizing the log wall. To make this work, one needs to use very dry logs, build in a dry climate, use smaller diameter logs, and use synthetic chinking.

A scribe fit building does not need fasteners for structural reasons. The cope cut lateral will "grab" the log below in a way similar to tongue and groove boards. Fasteners are added for other reasons, such as above for one. Fasteners ARE required between the floor framing or foundation and the sill logs minimum. I would also suggest, minimum, the top 2 or 3 rows be fastened together, to resist wind uplift. High wind areas, more.

[BradBradstreet]

use smaller diameter logs

Mike, when you say this what sizes are you thinking about? We are about 12" in diameter - but, they vary from end to end. Do you have any rules of thumb?

[MikeS]

Brad

No rule of thumb. Logic of what is happening in your system, understanding log construction and having done a few chinkers. I did see a MAJOR chinker company in MT go out of business, who built exactly the way your company does. They built a large project, things did not work right, and had MAJOR settling problems. The project was even featured on the cover of one of the log home magazines with an article inside, prior to problems.

When I build with lodgepole, I purchase logs from the same broker that supplies the whole Bitterroot Valley. I have seen 4% shrinkage with dry lodgepole. Rare building, but I was shocked. That was the only building where I had to go back and make some re-cuts for shrinkage. I had even put a moisture meter to those logs, and they were good. Shrinkage, using scribe fit cope system and standing dead logs is more like 2% or maybe 3%.

[Bob Warren]

Well...I have been away awhile. If anyone wants to see pictures or hear stories of a house at the end of the ice road, on an island in Northern Manitoba, just let me know. -30 the other day when we finished up and got out.


Rod had asked earlier if through bolts were necessary. In a hand carfted house they are a complete waste of time and money IF (and that is a big if) the builder does his job properly. Use dry wood, a good design and there is no need. Just like over scribing, shrink (or compress) to fit, and so on they are all ways to compensate for green wood. Dry the logs and do it right the first time.

[MikeS]

Bob

You are right in all ways. However, one additional issue exists in the Midwest and East, that is not so critical in the west, rot. Upward facing checks collect rain and do not dry out fast enough. Consequently, rot.

Upward facing checks are DIFFICULT to seal permanently, some impossible. I've had one home with a callback problem with an upward facing check. It will require constant maintenance by the owner. Used many check sealing products, and the best compromise is Emseal type foam, Denarco specifically. Caulk and many other products squeeze out of the check as it swells and shrinks.

With green logs, you control checking with the proper cutting and fastening system. No upward facing checks with green logs, and no surprising hidden rot in the heart (hidden red rot in dry lodgepole, hidden rot in a check in dry Englemann spruce). No problem with rain that follows a check into the window spline cut or an electrical chase hole, and penetrates into the house.

Even Lloyd Beckedorf swears by green, and he is in the Calgary area, east side of the Rockeys. He gets tight work...

There IS more than one way that work very well. Each region has different issues, and that is the reason you see so many different methods among quality and experienced builders. Through bolts are important to some systems, and not to others.

What kind of fastening system to you use to address wind uplift with the top rows of your homes?

[Bob Warren]

12" lag screws Mike. The question of wind uplift did cause me to do a bit more thinking about it last night. I have never heard or seen of a problem with the upper reaches of a log house to do with wind loading. I wonder if anyone else has?

It seems improbable to me that anything less than a hurricane would cause a roof on a log house to actually lift. But I could see a long straight stretch of roof catching enough wind to shift slightly, and push the top round over a bit. Anyone seen or heard of this?

So I wonder if the question is one of resisting lateral loads that have been transfered from the roof.

[MikeS]

Bob

I heard of one building that lifted in the eastern Rockies, Chinook winds. Curtains were pulled through some log laterals. I won't announce the builder, a very good and respected one, since I'm not absolutely positive of name in fact.

In the end, wind uplift is an issue to me. We get tornatoes in the lower MN, WI, IA and central/eastern US. We had a major blowdown in our area, including at least one if not four or five of our homes in the path. Major straight line winds. The whole forest was flattened.

It's reassuring, while something like that happens, to know the roof will blow off before the logs lift up and dislodge all the seals between the logs, or worse. Better yet, the whole house will stay put and together, and noone will be unhappy, contractors and owners included.

I believe Tom Hahney suggests the top three courses connected together, minimum. With uplift, you also loose lateral wind load stability and your engineering becomes a big mess for a few moments. I'd hate for logs to come back down, but not in the right place any more, and not fit back together.

[blue eyed devil]

Even if you do not live in Tornado Alley, wind load should always be considered.
Downburst winds (the ones Mike described) can happen almost anywhere.They produce tornado like conditions.
Heavy wind can happen in winter too.
A logging contractor in my town had a large new pole shed destroyed by a combined wind and snow overload.
A structural Engineer surmized that the parallam beams sitting atop the poles had actually rolled off the posts when the snow give way on one side during a winter storm.
The parallams had been attached to the posts with bolted steel plate but only on one side of each post.
Plates on both sides of the beam might have saved this building.