Barn maintenance

[Alan]

I rent a small barn to store equipment. It is a "sort of" post and beam structure with 6x6 main columns. Shorter posts beside the coulumns support 8x8 timbers spanning the width (21') and supporting a loft floor. Columns at the door opening are shorther and support a 6x6 oak timber as a header to carry roof loads over the opening.

I'm thinking the building is 30+ years old. It appears in good shape from the exterior, and indeed it is,,,, considering. I was expanding the loft about a month ago and started noticing things just didn't look right. The more I looked the more I found wrong. Then I added up the value of the stuff I keep in there and started getting nervous.

Here's the exterior shot. The area at the upper right corner of the door opening will be shown in in various closeups as this tale continues.

[Alan]

From the inside at the right side of the door opening, The column is the vertical member on the right. To the left of that is the post that carries the loft beam (8x8) running horizontally across to the left. There is a 1x board nailed across the column and post and carried to the next column over to the left, 6' away.

As it turned out, that board was all that was holding the post in place agasint the column. And the 8x8 was sitting there by gravity alone. There is a through bolt showing in the side of the column, I put that in when I realized how it was all built.

There are four cross beams in the building but none are connect to the columns. As a result there is nothing acting as a collar tie to counteract the spreading effect of roof loads on the rafters. The walls at the door opening were spread about 2" on each side at the top. If you looked close you could see a bit of sag in the ridgeline.

The short boards under the end of the crossbeam are shims I put there when I was expanding the loft and found that the building is out of level by 2" across a 12' span. I brought the low side up so that I had clearance for my truck strobes under the loft on the low side. It was when I found I could lift that crossbeam with almost no effort that I discovered that gravity and friction were the main fasteners holding things together.

[Alan]

The column beside the door had moved 1 1/2" out from under the header. Again, there was nothing connecting the column and header on either side of the door. Luckily the metal roof never carried a lof ot snow load of this would have been far worse. I still haven't figured out why the column moved outward without the header following. I would have thought that the rafters would have spread and moved the header, taking the column along for the ride. The best I can come up with is that wind loads made the structure wiggle enough to gradually walk the colunm out, With nothing hooked together there was no resistance to wind loading except at the endwalls.

[Alan]

I made up some fairly substantial connection brackets, one for each corner of the center bay. They attach to the columns with through bolts and are hooked across the width of the building with 5/8" rod and turnbuckles. Through bolts are backed up with 2x2x3/16" plate washers so I can reef everything up tight.

Once everything is where I want it I'll through bolt to the crossbeams as well. While not as good as knee braces these won't be head knockers and they will provide a fair moment connection to resist lateral (wind) loads.

[Alan]

Witht he turnbuckles in place I started drawing the sides back to plumb. The right hand side responded nicely, very little strain and no funny noises. On the left, where the loft is planked solid with 2x rough lumber, the front wall moved very little but the rear came back to plumb. I can live with the out of plumb in the one spot as I know it can't get worse now. The alternative would be to clean out the loft and rip up all the planking, or at the least pull all the nails (20d).

[Alan]

Where the header was off the column it now sits flush. Because I didn't know what was holding the top plate to the columns, and knew the header was floating I made up clip connections at each location. Again, everything is (or will be) through bolted. I just don't trust lags for holding anything structural.