Tag Archives: roof only design

Post Frame Ramadas

For the uninitiated, here is the definition of ramada from the source of all human knowledge, Wikipedia:
Park Shelter Building“In the southwestern United States, a ramada is a temporary or permanent shelter equipped with a roof but no walls, or only partially enclosed.
Ramadas have traditionally been constructed with branches or bushes by aboriginal Americans living in the region (deriving from the Spanish rama, meaning “branch”). However, the term today is also applied to permanent concrete, wooden, or steel structures used to shelter objects or people from the sun. For example, public parks in desert areas of the United States may contain ramadas with picnic tables, restrooms, water sources, etc. Since sunlight is more of an environmental hazard than wind or snow or rain in this part of the world, a roof alone provides substantial shelter. And because there are no walls in the structure, airflow is unrestricted, helping to keep the temperature below the roof substantially cooler than ambient.”

My friend and loyal reader LONNIE in COLORADO SPRINGS brought up this topic to me recently when he wrote:
“I’ve read many of your posts concerning roof only structures and the issues of not having side or endwalls so I’m wondering if a post frame building should be considered for a ramada?

I would want a shade structure as open as possible and definitely not fully walled. Is it feasible to design a post frame building with partial walls close to the roof to achieve a reasonable ramada use building?”

Mike the Pole Barn Guru writes:
For those who are interested in a ramada, post frame construction is going to be the most economical design solution. At short eave height (generally 10 foot eave and under) there will be few, if any, additional costs. As the eave heights increase, there become additional issues in preventing the buckling of unsupported columns in their weak (small dimension) direction. By the use of “scabs” attached to the sides of the columns, the potential buckling issues can be overcome.

For more reading on ramadas please visit: https://www.hansenpolebuildings.com/2014/05/ramada/.

When Less is More – Economical Buildings

When Less is More – Economical Buildings

The beauty of pole building construction includes being very affordable and being relatively easy to build.

Roof Only Building

Roof Only Pole Building

In the affordability area – a common misconception is to construct the building as “just a roof”, with the idea of walls being installed at a later date. And this will result in a significant cost savings. In most cases – no, and in some cases, the roof only building will be even more expensive.

Huh? Why?

Pole buildings work like uni-body cars. The steel building skin (roof and wall sheathing), properly fastened to the interior framing, is doing the structural work. As siding is removed, the frame needs to carry progressively more load.

With a typically fully enclosed pole barn, the posts (wood columns) are designed as what is known as a propped cantilever. The very stiff roof transfers loads to very stiff endwalls, thence to the ground. In the calculations for structural design, the applied design loads are divided by eight.

The roof only – the columns act as a pure cantilever – like the end of a swimming pool diving board. In these calculations, the applied loads are divided by two (effectively the columns are carrying four times the load). In a pure roof only, the “slenderness” factor also comes into play, as there is no wall to brace the posts laterally (in the direction of the wall).

Greater loads carried by the columns, also mean the column embedments (the holes) are going to be larger in diameter and/or deeper. Plan on having to completely concrete backfill the holes, as opposed to just a small quantity of concrete around the base of the columns.

For very short buildings (10’ eave height and less), the structural differences between enclosed and roof only are negligible – some savings could be found in installing walls at a later date. As height increases, the issues become magnified, to a large part because in the design calculations the height of the column is squared.

While a 20’ tall wall is only twice the height of a 10’ tall wall, the applied loads are four times as great, due to the square of the heights.

Trying to find a balance in all of this? Leave the long (eave) sidewalls open, and the endwalls covered to the ground with siding. This will usually yield the best structural and least expensive design solution.