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Window and door settlement and alignment between

Started by Andy2018, June 19, 2018, 11:41:07 AM

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Andy2018

Hello all!

I have a short question regarding settlement: when log house is build when there is a need to align window upper level and door upper level how to manage the settlement? As i understand when window is attached to a window buck which is attached to sill log below and to vertical slots on the sides, when house is settled then window will go down together with sill log and logs below against ground level. For example window starts from 4th level of logs till 8th level. Then when house will be settled, then window will appear below the original height as 4 level of logs shrinkage (around 10 cm).
While the door which is attached to the sill log will stay on the same position against the ground- it could probably move below just as the one sill log will shrink.
If above things are correct, how upper level between doors and windows are aligned during house construction?

Thanks very much in advance!!

D L Bahler

Will you be using a traditional Russian log building technique with heavy posts framing your windows and doors? Or will you be using an american technique? This will affect the way that the windows and doors align with settlement issues.

If you have heavy posts around your doors, accounting for settling is easy. Here you cut the door uprights to account for settling of the logs -calculate the shrinkage of the logs, and make the door posts that much shorter than the opening.

To hide the gap, there is a notch cut into the log above the door. If this is not clear I may be able to provide some pictures. 

jander3

installed with a key.  logs settle 3/4" per foot of wall height.  gap is left over top of window or door, cover board installed.  I think I have photos of this on my cabin thread.  search on The Stump Ranch on the forum.

Don P

I understand the predicament Andy. If you can tolerate the settlement differential then that is the easiest thing. If not you need to make provision to lift the window and reinstall it later when settlement is done... I've never done that but if final alignment is critical, well, you gotta do what you gotta do. I do have a wall height shrinkage calculator here;
http://forestryforum.com/members/donp/logshrinkcalc.htm

In reality logs refuse to cooperate and do the math. Those numbers will be averages.

D L Bahler

In a traditional European style of log building, it is typical to have a header beam above the door that will conceal the settling differential. To do this, you simply cut a deep groove into the beam on the under side, which fits over the window just loose enough to be able to move up and down. Of course on a door, you can only cut a notch on the inside. 

one thing to keep in mind is that there is some settling that occurs from drying, but the logs will also have some degree of movement throughout the year from temperature and moisture changes within the wood, or at least this is the way I was taught (in Switzerland). So for this reason, we can't just wait for the logs to be done moving, because they will never stop this process even after 500 years. 

Typically we would frame a window or door opening with uprights at least 10 cm wide. The logs have tongues on the end that fit snugly into grooves cut into the uprights. These uprights are not fastened to the horizontal logs with any nails or screw, so that they can move freely. They are also cut the appropriate distance short of the opening height so the the log course above will never rest on the vertical timbers. 

This of course is speaking from the Central European tradition, which is in many ways very similar to the Russian and Scandinavian traditions. American log building is very different. Your profile says you are from Russia, so I naturally assumed you would be building a Russian style log structure. 


Andy2018

Dear all!

Huge thanks to your replies and you time. In principle i think Don P got my problem is that after the settling will be done, then top level of window and door will be located differently against floor level, in case when initially they are alligned, since window will move down as 6% of tolal length of the wall under window against floor level and door will stay the same level.

I'm using americal way of construction of window bucks so that keyways are cut and sliders are installed into it, also keeping extra space above window/door as 6% of window/door length.

Thanks a lot!
Best regards
Andy.

Don P

One thing to remember shrinkage and settlement are two different things.

Settlement is everything that gravity can do to a wall. That can be looseness of fit between logs, cope spread, or "slumping" in a scribe fitted log, and shrinkage of the logs. In a typical "American" style milled log where the logs bear basically flat on flat there is no slumping to account for.

Shrinkage is usually taken as radial shrinkage from the US Forest Products Laboratory shrinkage tables. Those shrinkage values are from very thin sections of wood which a free to shrink. In a log section you usually don't see as much shrinkage as those numbers. Cross grain, rays, pit connections, internal stresses tend to bind the logs compared to a thin section. Also, when a log opens up a check shrinkage has occurred but the check absorbed that amount of shrinkage so the overall height of the log has not lowered as much as the shrinkage numbers.

6% in an 8' tall wall is roughly 6" of settlement. There is nothing wrong with building for that possibility in windows and doors but in reality I can't recall more than about 1-1/4" of settlement in any of the milled log homes I've built. Where overestimating can get you into trouble is with stair settlement allowances.

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