pole barn and snow load?

i got this late 60's 102'x56' pole barn/shelter.
The poles are set 11'center squire.

The purlins(nailed with 3 spikes each end)to the poles.
rafters are 2x6,4' apart,then 1x8 boards across and metal roofing on top.
The highest part is 16' feet high and runs the full 102'lenght. the roof there spans 22' between the poles.(look at the dinky construction of the rafters)


I got between 1 and 2.5' of snow on it now,i wonder how much it'll hold before it'll come south No deflection of rafters or purlins detected yet

In my experience it depends a lot on the composition of the snow. If it is light and powdery it may not weigh much at all, if it is wet it could be very heavy. Around here in the lake effect snow belt in northern NY it seems that buildings collapse most often when we have a heavy rain on top of the snow, since the snow prevents the rain from running off. I'd be a little worried about your barn if it were mine, but I don't know what you can do about it. We shoveled the roof of a 28x50 or 60' pole barn once when it had up to 6 feet of snow on it in places. It took all day, and as well as being smaller than yours it had a steeper roof.
Zach

It looks like the center might be the weakest, you could run chains or cables across the clear span part. If they can't spread out they shouldn't come down. In our area last year a lot of buildings went down. mostly pole barns. Didn't seem like was any particular brand, Mortons seemed to go down also, but they probably are the oldest. We have a old Srurdi-Built, my dad built in the early 60's and it is still here.

If that pole barn was around here it would have been a pile of wood and steel years ago. We have to figure basic min 60#/sqft snow load. The bigger it is The higher, and then any static loads added inside. We always either mortise in the top plates and /or through bolt them, and then we use trusses that are engineered to hold that load. We also have to consider wind loading for structures like that. If you also have animals in the building, they will generate moisture and heat that will cause even more snow to collect on the roof at certain temps. Zack is right that the moisture content in the snow will determin weather the roof structure survives. Looking at your pics.; Frankly I would get anything you value out of there if you have a lot more snow coming. Good Luck, The Acg.

If your pole barn was totally enclosed and you had a nice day around 32 degrees. You could park a tractor inside and let it run. The exhaust has been known to heat up the sheet metal and the snow just slides off. A friend of mine had the sun take the snow off the south side of his pole building, the north still had a good load. The big door was open and he was about 10 feet from entering the building when the roof came down. Knocked him back about 20 feet. Snow is not the friend of roofs.

Get some heat in that building. Torpedo heaters, set a tractor on fire, whatever. Heat rises and will start melting the snow on the roof.

I"d be shoveling if it were mine.

In the 1950s we had a building with snow drifted to the peak of it during a blizzard. It was many hours later after the snow had stopped when the first rafter cracked. Several quickly after that as they took on added weight from the failure of others. Luckily the roof never failed and I"m sure it was because we had already started to move snow off of it.

In my area of Michigan there have been roof snow removal subcontractors, in bad winters. You just have to make sure they are insured.

I myself have a roof rake, large ranch home. My roof is 10' up from grade at the eve.

I did put a 3/8th rebar with a readyrod welded on trough the purlins and poles on the clear span , and cranked it back together a number of years ago.

Is that picture of the outside the current condition ? I f so it looks fine to me. Lumber has a tremendous capacity to be overloaded. If nothing is bending I think you are good. It is of some concern that there is so much water staining in the photos. Might be more rot than you are aware of. I think the week link is the nails holding the headers or purlins to the columns.

It's not what is on there now but what will be added to it. The forecast for parts of MN, IA and WI is for rain or very wet snow late this week. That will be a heavy addition to what is already up there. And we are still not half way through the winter!
I spent half a day on Sat and then about the same amount of time today removing snow from roofs.

For the snow load you picture I doubt it's in much immediate danger... but if that snow got water laden or you got a good strong wind... all bets are off. I think what concerns me most about that barn is the general lack of proper bracing. A rafter can carry a lot of load in that configueration IF that post/purlin system doesn't start to twist and sway... but there isn't a lot there to prevent that. As a comparison here... a building that size would have a full 'W' truss with probably 2x8 or 2x10 top and bottom chords, spaced on a minimum of 4' centers, 2x10 or 2x12 wall plates and 2x4 strapping on the roof and walls at 16" and 2' respectively. IN addition there would be two knee braces on every truss and several runs of 2x4 above the bottom chords of the truss, end to end... as well as more diagonal corner bracing on the top chords towards the end of the building.
This is clear span I'm talking about... but still probably 3 times the material.
I'd also be concerned about the stains on some rafters. Leaks above there? Rotten wood? Nails?

As someone else suggested, it might be a good time to remove the valuables...

Rod

Thanks for your input guys.

There is more snow on that roof than the pic suggests.
The wood is sound,the stains are just that,stains'

I got pretty much all i own in tractors and tools and such under that roof.My shop is under it too.

I had at times up to 3' snow on that roof,but the barn is getting older(i didn't build it though)and i had planned to re enforce the clear span rafters and double up the headers last summer.But i guess it didn't happen(it seems its always next yrs country up here)

I don't look forward to it, but i think i head on that roof tomorow and start clearing it off before the next snow fall brings it down.

Been there done that too, I"ll get to that tomarow, only "tomarow" never comes for me. I hope you can save it. Good luck.

If I was your insurance agent, I wouldn't write insurance for that building. I have built about a dozen pole buildings, and around here they need to be engineered for 50 lb/sq ft snow load. I doubt yours will stand a 25# load.

As I see it your 2 main areas of weakness are the center section with its 22 ft span. If I wanted to keep that building, I'd bring in enough lumber to form W trusses at every rafter. Sure they won't look like factory trusses, but you can get a lot of strength with a 2X6 bottom cord and 2x4 for the webbing. Years ago, there was a booklet put out by the ag extension service having the details for building pole barns and making your own trusses by using 1/2" plywood for the joining plates. It is less convenient to do it now, but is a lot easier and cheaper than repairing or rebuilding a collapsed building. If you do the truss work on that 22 ft center span, use a nail gun to put lots of nails to attach the chords and webbing with the plywood. Take a little extra time and clinch over the excess nail length on the backside.

The second issue is the lack of sufficient nailing with spikes from the rafters to the poles. 3 each is about 1/2 of what you should have. As none of these rafters is "let in" to the pole, its entire load carried to the poles is supported only by those 3 spikes. Each spike can hold only so many pounds before it fails by bending or shearing. Make it 5 or 6 spikes at each pole junction.

Your steel rod reinforcement with 3/8" re rod with probably 3/8" reddi rod is way too undersize, but certainly better than nothing. When I do that kind of reinforcing, it is min of 1/2" rod on short spans, and most commonly 5/8". On your 22 ft span, 1/2" rod is the minimum I would use. When the tension gets high from heavy snow, standard size washers behind the nuts will pull right into the wood. So make your own washers out of flat stock steel 1/4" thick and about 2" square.

With the size of that building and its likely usefulness to you, I think it can be adequately reinforced.

Paul in MN

I have a shed dad moved onto theplace as an old used lumber shed. Then he added a leantoo on it as a shallower roof line. It's 40x 36 or some such. Very shallow roof. Very old. Lot of 2x4 wood. The walls are framed 2x4, but the end walls are kinda pole barn look to them. Really old odds & ends wood.

It seems to hold up. One summer I rebuilt one end wall, the old siding was rotting apart. Pullerd the old siding off, and wonder what holds it up?

I do need to shovel it every few years.

I've learned that, rain is the enemy, if it rains on a deep snow pack on the roof, it really adds the weight, the water will run to areas and pile up the weight unevenly.

As I get older and lazier, I will shovel out a path or 4 up & down the roof, so the water will have a chance to drain all the way off in those channels.

Any sun that comes up will heat up the exposed channels and melt off more snow faster.

Seems to me the channels, down to the roof, are a good deal, and don't have to maybe do the _whole_ roof.

Old wood with old nails seems to hold a lot more than new wood and new nails.

Lot of roofs going down here in Minnesota tho, we got a lot of snow early on, and more is coming, with perhaps a 3rd rainy period before the snows.

Think that rain is the real enemy.

--->Paul

How old is this building? Has it,or parts of it ever fallen in the past? If it has a good long history, with prior winter storms,... it will probably be ok?

The building is around 50 yrs old.
It must have stood the time well though,
By the looks nothing has been done for repair or upgrade, other than I put a new steel roof on it 17 yrs ago,at that time it was only used for hay storage and calf shelter.
I have later sheethed a part in for a shop and after the beef cows went i used te remainder for machine shed.
It is the only building i have on the place besides the house.

With all those posts it ain't gonna fall down. At least not all at once. the weakest spot looks like the peak span but I doubt that's the heaviest snow load either.

A barn with that little slope on the roof would never withstand the snows we have around here, near Spokane. Our outbuildings are almost always built with a 4/12 or 5/12 pitch, so the snow will slide off the sheetmetal roofs. A couple of years ago, we had over 6 feet of snow accumulation and it brought down lots of buildings, including some pole sheds that had been there for years. Lots of others would probably have come down except for the fact that the owners employed people to shovel or blow the snow off them.

But if your barn has done OK for 50 years, it must be strongly enough built for your area. If it was my roof, I would watch for any drifts developing on it, and would consider shoveling off any areas that got deep. If you do get up there, be super careful, since the snow covered metal will be incredibly slick. If you have access to a small snow blower, that might work well. I hate being on metal roofs when they are dry, much less snow covered! And always have a safety line to grab if I start sliding.

As far as heating the inside of the barn goes, I think you would need a lot of heat. And without a vapor barrier, any combustion heat will result in lots of condensation inside that you will have to deal with somehow. If snow will usually slide or creep down the slope of your roof under normal conditions, it might be worth it to heat the place up.

I hope your weather turns warmer and less snowy. It is flat scary to worry if a roof might come down...Good luck!

Looks to me like a lot of work and danger to life and limb to shovel that off. If you heat it, then heat it long enough so all the snow melts and you don't get a layer of ice between the snow and roof although the sun will do the same thing and then it refreezes at night. Exposed screw heads will make it a pain to shovel and won't help ice slide.

The discolored nail heads looks like standard rust from condensation on the nail heads. May not be indicative of the entire nail rusted but... They probably didn't use galvanized nails but those leave a stain as well. The discoloration of the 2 bys appears to be staining from condensation dripping on them from the roof. May or may not be a problem without tapping on them with a hammer to see if they are rotted or not.

Big knot in one pole doesn't look good. What I would do is get some 3/8" lag bolts and put in two per pole at the beams equidistant. Use a drill and check your cuttings for good or rotted wood, particularly the poles. Any weak or rotten 2 bys can be replaced or I'd probably just sister in another on top and tack it good with a nail gun.

As old as it is, I'd be more worried about the posts being rotted just below ground level. Dig a few out and check them. Particularly where water may sit. They can rot inside the concrete around them. Individual posts can be replaced with laminated treated 2bys. Plenty of info in the archives on how to do that.

Really boils down to the type of snow as well. If you can pack it and make snowballs and snowmen, then it is wet and heavy. If not, then it is the light stuff. Suppose you could cut a sq. ft. of it and put in a bucket to get a weight on your bathroom scale. Maybe a little more scientific so you have a number to use with all these other live and dead load numbers being tossed around. Let us know if you do and how deep it is. Good luck. I think you are all right but never say never as they didn't say at the metrodome.