Tilting foundation beam on cabin frame 12x18 plans)

Started by ethulin, June 26, 2016, 05:54:25 PM

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ethulin

Last summer we put up the foundation, floor, and walls for a cabin based on the 12x18 plans. We came back to continue work the following summer, and saw that one of the beams that the floor joists are resting on seems to be twisting out. We noted that neither beam is tilted at any other post, including the two other posts on this block, meaning the beams are straight at the other 5 posts). We know that this was not like this when we left last summer, so we suspect some sort of settling is responsible.

We were hoping that you might have some suggestions on how we might go about remedying this, as we don't really have any idea how to proceed.

Here is a photo: https://goo.gl/photos/SscXCT2yMJvydJ598

NathanS

It can be normal for wood to twist as it dries. Were those beams green when you bought them?

Did you check the posts for plumb?


Don_P

That is why building codes require lateral support at beam ends and at intervals depending on size and span. I'd block them well, plumb at each post.

ethulin

Thanks for the advice.

Yes, we checked the post for plum at the time of construction. Honestly I just assumed the lumber yard would not have sold green lumber, but maybe they do? It is pressure treated, if that gives any indication to whether it is green.

I can certainly see the value in having that lateral support at beam ends, and should certainly do so now.

Could you give some more detail on how you would go about blocking them now? Sorry for the presumably obvious question, but we are incredibly novice and very much appreciate your advice.

Don_P

Treated lumber is generally sold at high moisture content, you can special order KDAT treated, kiln dried after treatment. Nobody does.

You'll need to figure out how to lock (laterally brace) the good locations, which can be dimensional lumber between girders and strapping to hold it, then work your way across the floor working the tipped end back to plumb. You probably won't get it all but try to lock it so that it can't move more, at either end, as it dries. This was a tree with a spiral and as it dries that spiral is showing itself. However... I saw blame creeping in, that is not the fault of the lumber it is common, it is the fault of the method of construction. Remember dry framing lumber at the building supply is not fully dry, 19%, it'll dry and shrink down into the low teens or below in service. The lateral bracing is really intended to keep those beams from flopping over in the wind or a earthquake. This mistake began with the choice of foundations.