Tag Archives: single slope pole barn

Single Slope Roofs

Ranking and Railing About Single Slope Roofs

Long time readers have read my beat downs of single slope roofs on pole buildings in the past: https://www.hansenpolebuildings.com/2014/11/single-slope-roof/

Single Slope BuildingLet’s take a gander at how wonderful a single slope roof pole building will work for an RV or tall equipment building.  We get folks coming to us for a quote with the mistaken idea single slope roofs are the way to go…and will be less expensive to build.

We will assume the building is in snow country so the design will slope from the high (door) side to the low eave in the rear – so all (or most) of the weather dumps off the side opposite the doors.

Sweetness! Far less snow to deal with on the door side!

In this pretend building, we can imagine a 40 foot or so depth (in the direction one will be driving in). The ideal sized overhead door for a recreational vehicle would be 12 feet wide by 14 feet tall. If it can be driven legally down the highway without the need for special permits, it will fit through the door. All is good so far.

To keep the building from being so overly tall, and yet still allow the weather to run off, we will imagine a happy compromise at a 3/12 roof slope. While this sounds fairly flat, on our 40 foot wide building, the front wall is going to be ten feet taller than the rear wall!

So what happens if the building slopes from say 20 foot tall on the door side (20 feet is twice the height of a basketball hoop, just to give a perspective), to ten feet on the low side?

The 14 foot tall door will easily fit on the 20 foot tall wall. No problems – lots of height above the door.

Door opens up, 13 foot tall RV easily sails through the 14 foot high door….we are crusin’ now….

Until the RV is pretty well all of the way into the building and it smacks into the roof system, making nasty noises, placing a healthy dent on the top of the RV and being generally embarrassing.

Now how did this happen?

Remember the low eave height was only 10’. Allowing for the thickness of the roof purlins and allowing for a nominal four inch thick concrete floor, the 13 foot tall RV starts to clobber things at 16 feet from the rear sidewall!!

A far better and more economical design solution would have been to use a 16 foot eave gabled building, with the big door in an endwall.

No nasty slapping sounds and the weather comes off the roof on each side, out of the way of the overhead door! And just to cap things off, the gable building will cost less. Guaranteed.

Single Slope Pole Barn

When the Requests Are Interesting

My encouragement to potential clients is to share with us your troubles and your goals – and let us structurally design for you the best solution which is a marriage between wants, needs, budget and available space.

Finding happiness in a new building, is much akin to success at finding the person to become the “ideal” spouse. If one goes into either situation with too much advice from well-meaning friends and lots of preconceived notions as to what they think they want, chances are the satisfaction level with the experience is going to be less than it could or should be.

Here is an actual recent request:

Single Slope Pole Barn“I will be building a single slope (roof and 3 sides covered with corrugated steel) pole barn similar to one of your designs online.  My ideal design is 20 by 30 with 1 foot roof overhang.  The structure consists of (3) 20 x 10 bays.  High side to be 12 feet and low side to be 10 feet with bay entry at high side.  I will only consider steel posts (8) for the vertical pole construction.  For the roofing material please include 2 each opaque roof sheathing for each bay (natural lighting).  Design to include high wind (50 mph) with 18″ snow load.  Please provide a detailed bill of material including foundation (30 to 36 inch footing depth (no slab) with bid.  I will be requesting engineered drawings.  The shipping destination is xxxxx zip code so please include shipping total and tax in bid.

I look forward to receiving your bid and perhaps purchasing your product.”

Obviously, this person felt they had their solution pretty well figured out…..

Except they neglected to do any research, which would have saved them from having to write out their wants and click submit!

Here is my take on their request:

Single slope buildings are rarely the best practical design solution. https://www.hansenpolebuildings.com/blog/2014/11/single-slope-roof/

With the building sloping only two feet across 20 feet, the 1.2/12 roof slope is not going to be conducive to moving weather off (rain or snow) and is so flat the steel warranty will be void.

Here is where the two of us are most certainly not a fit: “I will only consider steel posts (8) for the vertical pole construction.” As we don’t use columns other than wood, the specifying only considering the use of steel posts, eliminates us (as well as many others) from possibly being suppliers. The use of only eight “posts” means the 20 foot walls are going to have to span from corner column to corner column – while this might not be an issue in all steel construction, wood wall girts will be hard pressed to meet this criteria.

It also means trusses or rafters which must clearspan the 20 from wall-to-wall, which could significantly affect both project cost, as well as the interior clear (vertical) height.

For the roofing material please include 2 each opaque roof sheathing for each bay (natural lighting).” This request, especially given the near flat roof slope, is probably dooming the finished product to at least roof leaks, if not worse.

Read more about roof skylights here: https://www.hansenpolebuildings.com/blog/2014/09/skylights-2/

This client has not done his homework, as 50 mph (miles per hour) is not a high wind speed when the minimum Building Code requirement anywhere in the United States is 85 mph.

More on wind speeds here:


The 18 inch snow load is not going to be what his Building Official has in mind either: https://www.hansenpolebuildings.com/blog/2013/11/design-criteria-3/

And, of course, no true pole building kit package supplier worth their salt is going to hand out a materials’ list prior to a client ordering. Why not? Read this: https://www.hansenpolebuildings.com/blog/2012/03/materials-list/

While we do include delivery to the site as part of our quotes, sales taxes are typically a different situation altogether as noted here:


Perhaps the requirement of engineer sealed drawings will help to steer this client closer to what might be a more practical and affordable design solution while still getting his ultimate goal – a single slope roof design.