Tag Archives: prefabricated truss drawings

Things to Know When Adding onto an Existing Pole Building

Things I Need to Know When Adding on to a Post Frame Building

home-addition-150x150Real life scenario – one of our clients is adding onto the end of a clearspan 24 foot wide by 36 foot long by 10 foot eave post frame building. The add-on makes the structure another 24 feet longer, same height and roof slope.

Piece of cake – right?

I’d written an article about this very subject previously, so the Hansen Pole Buildings’ Designer had the advantage of being well educated in this area: https://www.hansenpolebuildings.com/2015/08/building-endwall/.

There were some known challenges in this addition. The client needed a 12 foot tall overhead door in the new endwall. Luckily the existing roof slope was 7/12 and by using interior columns and rafters, instead of clearspan trusses, the door could be placed in the center of the endwall.

Problem solved…..

However, the existing building has an 18 inch overhang beyond the endwall, which was not communicated originally. The challenge was resolved by attaching the roof purlins in the bay closest to the old building to the old fly rafter.

However a larger challenge appeared – the client wanted to remove the endwall columns from his old building. The client knew this, the Building Designer knew it, however it was not communicated up the chain to those who were having to do the structural design for the building.

What might have been helpful, would have been getting our hands onto the truss designs from the existing building. However, no truss drawings could be found.This made it impossible to determine if the existing endwall trusses were designed as a clearspan, or if they were reliant upon the existing columns for bearing.

In the end – the solution was to span the end of the existing building with a large LVL (https://www.hansenpolebuildings.com/2013/01/lvl/).

So – things I want you to tell me about your existing pole building….

If you have the building plans and/or truss drawings, please share them with us.

Any paperwork you have from the original purchase (we want to as closely match what you have as possible).

Send us photos of the outside and inside of the building. Make sure they are clearly identified, so we know which wall the photo is showing.

Will you be making any changes to the end of the existing building? Will siding stay on the building, or will some or all of it be removed? Do you plan on moving or eliminating any columns?

Provide the measure of the eave height of the building (https://www.hansenpolebuildings.com/2015/02/eave-height-2/). Make sure to do this right, as this will be crucial in getting the best possible result.

Measure the distance from the bottom of the pressure preservative treated splash plank, up to the bottom of the base trim.

If the end of the existing building does not have a prefabricated roof truss on it, the roof slope needs to be verified.

Be prepared to have to answer more questions – the more we know about your existing building, the happier you will be in the end.

Why 10d Nails?

Readers: This is another one of those “Dear Pole Barn Guru” questions where the answer is so lengthy it deserves an article all of its own!

DEAR POLE BARN GURU: Why 10d nails?

Do you know how difficult it is to get 10d nails? Every hardware store in my area has big boxes of 8d, 16d, and even 12d, but NONE of them have 10d.

I was able to find them in the small 5 pound boxes, but those are over $15 a box! A large box was a special order. I got them, but what a pain in the butt. SAM in PORT ORCHARD

Dear Sam: Nails are sized by engineers in order to get the most strength value out of a connection, without resulting in failures usually due to (in the case of nailed connections) wood splitting.

Most building plans and prefabricated truss drawings will specify 10d galvanized commons for framing installation. These are three inches long with a 0.148” diameter. Because we know not every lumber yard or hardware store has them in stock, Hansen Pole Buildings does offer, for purchase, competitively priced “strip” type framing nails which fit many common power nailers.

Lesser diameter 3 inch nails (typically referred to as “box”) cannot be substituted.

Nails greater in length than 3 inch, used for general framing, can cause lumber splitting with catastrophic results.

Researchers have found when a nail is driven into a board, further than the lumber face width, the board will likely split (example: driving nail 2” into 1-1/2” board face).

The building plans have specified 10d common (3” long, 0.148” diameter) framing nails. Proper nailing technique use is essential for ideal results and adequate building performance.

Nails distances are measured in several ways:

  • “Edge distance” is the distance from member edge to nearest fastener center, measured perpendicular to wood grain.
  • “End distance” is the distance measured parallel to grain from the square-cut member end to nearest fastener center.

In photo below, board “end” has white tag stapled to it. “Edge” would be either of the long sides.


  • “Spacing” is the distance between fastener centers measured along a line joining their centers.
  • For ideal results, install 10d common nails so no nail edge or end distance is less than 3/4”.
  • Space nails no less than five times the nail diameter (with 10d common nails 5 X diameter is roughly ¾”) while 1-1/2” is preferred.
  • In any case, edge distances, end distances and spacings shall be sufficient to prevent wood splitting.
  • When a bored hole is desired: To prevent wood splitting, bored hole diameter shall not exceed 75% of nail diameter.

EXAMPLE:     For a 10d common nail, maximum bore hole would be 0.111” (7/64” bit would be safe).

  • Install nails perpendicular to member surface.

I hope this answers your question about 10d nails… and a whole lot more.

Mike the Pole Barn Guru