Tag Archives: adding to pole barns

Adding Onto an Existing Building Endwall

Picture this…..

Your present pole (post frame) building is just not big enough. Whether through lack of planning on your part, or the previous owner – there just is not enough space.

So – just add onto the end of it. Simple, right?


Building EndwallAssuming the existing building endwall is fully enclosed, there is a very good chance the building was designed using what is called “diaphragm design”. If the existing building endwall steel (or structural sheathing) is removed, the entire building should now be reanalyzed by a registered design professional (RDP – engineer or architect) including the portion being added on.

This extra length can cause some unforeseen issues – shear intensity in the roof may be too great for the roof steel or sheathing, requiring some special design consideration in order to resolve.

The shear intensity also increases in the endwalls – not just the new endwall, but also the one on the opposite end of the building. This may necessitate having to reinforce one or both building endwalls with plywood or oriented strand board (OSB) sheathing in order to make them stiff enough to adequately transfer wind loads from the roof to the ground.

Special consideration needs to be given to the old endwall. Chances are the old corner columns are not sufficient in size to prevent failure due to wind loads. They may need to be reinforced or braced to prevent possible failures.

Trying to remove columns from the old endwall? Just because there is a truss on the end, does not mean it is designed for a clearspan. Often end trusses are designed to bear upon some or all of the endwall columns. If the existing building has dimensional lumber rafters as opposed to trusses, it further complicates matters.

What if there is an overhang on the existing building endwall?

If old and new portions of the building are the same width and eave height it could be possible to attach roof purlins from the addition to the fly rafter of the existing overhang with joist hangers.

No matter what the case – the more information which can be provided, the better. Plans for the existing building, as well as photos are always helpful, and be prepared to answer lots of other questions.

And – make sure to only add to an existing building endwall under the auspices of an RDP – a Registered Design Professional. The failure you save, may be yours!

All Steel Buildings: Non-expandable Building Frames

All Steel Buildings: Non-expandable Bearing Frames

I learn at least one new thing every day. Seemingly whether I try to or not, which makes it ever so much more interesting. I’ve deduced this – when I stop learning, I am dead.

This morning, Eric (one of the owners of Hansen Pole Buildings), asked me, “non-expandable bearing frame – any idea what this means? I’m sure it is something off a steel building quote”.

I told Eric I would have to research further, and once again (thanks to the wonders of the Internet) I quickly had the answer.

This answer came from an all steel building website. A “main frame” is an assemblage of rafters and columns which support the secondary framing members and transfer loads directly to the foundation. An Expandable Frame is designed to support any future building additions with the same width and height which will tie-in to this frame. A Non-Expandable frame is used when X-bracing is not allowed in the endwall. It provides added structural support, compared to the bearing frame. It is also used in Hangar Buildings to support the Header system for the hangar doors in the Endwalls.

While all of this is a mouthful – it did set me to pondering.

My educated guess is, the majority of all steel buildings are designed so as the ends of the buildings cannot be added on to. Or, at least not without major structural considerations.

Post frame (pole buildings) can have their ends added on to relatively easily – however some thought still must be involved.

The easiest – is when the original design incorporates trusses on the endwall which are designed to carry the roof loads from a future “next” bay. In most cases, this takes having a double truss on the endwall which will be later added onto.

There are some things to be looking for when adding to the end of a pole barn.

If the siding is to be removed from the end of the existing building, the adequacy of the roof skin and both endwalls needs to be checked for the ability to carry the shear loads. Not just the new endwall, but also the remaining endwall of the existing building, which is opposite the proposed addition.

Are the existing endwall columns to be removed? This can be tricky – as some buildings are designed with rafters on the endwalls, rather than trusses, or the existing end trusses are not designed to be clearspan, they require the support of the endwall columns.

In any case, the adding to the end of an existing building is best done when involving the assistance and experience of design professionals who can do an analysis on the existing structure, as well as the proposed overall new building. This is the assurance of a result which will perform structurally as desired.