Cut a large opening in the log wall for a patio door

[heimlaga]

Of course, there are no blueprints. When they had smoked the tobacco package empty, it went into some fire. With blueprint and all;-)

 

[Tykon]

I think you should let the door opening be the size it is!

Around an opening in a log wall, there are either swords, which are standing planks inserted into grooves in the ends of the logs, and dowels that are driven into the logs from above and down a few tens of centimeters from the opening.

Log walls generally function so that you can saw as large openings as you want, however, after some time, the wall begins to bulge because it lacks support from any sword, and the joint usually starts to slide outwards because the dowels that prevented the logs from sliding over each other have been removed. This process continues slowly, and eventually, some log begins to crawl out of the wall.
When various owners have realized their visions and removed the supporting structure piece by piece, it is no longer possible to renovate the house. Many fine houses that could have lasted for another 200 years have been ruined in this way.

I have worked as a carpenter and patched up old logs, so I know how bad it can get. Furthermore, I have an engineering education in my background and understand structural mechanics.
The latest project was a house where someone had enlarged all the window openings. When I arrived, the upper part of the house was supported on half the length of the house solely by the window frames and some plank stumps inserted as filling beside the frames. The log walls between the windows had totally collapsed, and someone had chiseled away half the thickness of the protruding logs to be able to put up panels inside.
The only way to repair it was to lift the upper part of the house and partially rebuild between the windows with new logs. Dowel and insert swords. It was a lot of work. Just because someone felt they wanted bigger windows.

Now you already have a door opening that serves the practical function. Then you should not saw any more.

How slow? It feels like a relative question, but if nothing has moved for 40 years, it should be quite safe, right?
There is a window that has been widened and a door cut out next to it, not done by me, so I don't know how it was done, but I became a little worried/curious. About 1.5-2m from the outer corner and 1m from the inner wall, which I do not know if it is tied together with the outer wall. Opposite the inner wall is an outer wall on an extension (the log wall and inner wall with annex form a cross from above).

 

[heimlaga]

Hard to know...... but in 40 years it should have become noticeable that something is starting to happen gradually....... I would guess.....

 

[Tykon]

That's roughly the kind of answer I was expecting
I've inquired with someone who knew the house before the saw came out, and most likely the side towards the corner is untouched; it's just the other direction that has been widened.
Are there dowels along the entire length of the logs, or are they only around openings/joints? Built in 1905 if that matters, and it was widened 30 years ago, not 40 as I first wrote.

 

[Blwrgrl]

Bought myself a house with a timber frame, moving in October and read up a bit about the frame now but still worried after reading about your worry 😯😯 if you're lucky, the timber is not smooth-planed but U-shaped along the bottom, so it doesn't move sideways as easily as if it were flat - do you have somewhere you can see a knot/end of the timber? I will take a look to see how the previous owner made the extension exit (2008) as soon as I move in - both out of worry and curiosity 😁

 

[heimlaga]

Normally, one always cuts, saws, or mills a groove in the underside of the log. The groove is a hollowing that fits with the curvature of the log below. You don't see this on the corner joints because they are usually planed flat against each other. The corner joints have been shown to hold significantly better if they are planed flat against each other, according to one of the guys who taught me logging.

In the settler lands of Västerbotten and Norrbotten, it happened that they let the groove run out into the corner joints to speed up the work. Attention to detail couldn't be too meticulous when a farm was to be built and cultivated in the wilderness.

But as usual, there are exceptions:
The folks from Skåne and Blekinge and the carpenters who built certain medieval churches logged with squared or square-sawn timber and a shallow groove that provided room for a bit of moss in the middle. They are said to have fastened the walls extraordinarily tightly to get control of the timber because the groove didn't grip the planed underside of the log. I have never seen such logging.

 

[Blwrgrl]

Expanding is not an option. Half of the house has already been extended previously and built with standard studs. But unfortunately not in the part of the house where I want the door. I think it should be fine to widen as there was already a 90cm door there previously, but now it will be 140. But if you place planks on the inside and outside next to the opening and insert a threaded rod straight through every 3 logs and screw them together so that they clamp the logs, I think it would take a lot for the wall to collapse outward. It should be stronger than the tenon/chase.
/Anders

Do I understand correctly that you can't use the building permit-free 15 sqm? I was thinking if you could keep the opening and then place the doors on the extension.