Tag Archives: registered engineer

Dear Building Officials

Dear Building Officials

I have met (either in person, via phone or technology) more than just a few Building Officials, Inspectors and Plans Examiners over my nearly four decades of post frame buildings. I have even been privileged to be a guest speaker for several groups of these fine folks, regarding Code conforming post frame construction. My expert opinion – collectively folks who work in Building Departments most genuinely go above and beyond their call of duty to assist building owners in building safe structures.

Several members of Building Departments are either subscribed followers of this column, or regular readers of it via Linkedin posts. These are most likely ones who are providing excellent service to those venturing into their offices.

My most recent two articles covered questions we require our clients to ask of their building officials in regards to pre-construction of a new post frame building. With these answers in hand, we can assure our contracted Registered Professional Engineers have data necessary to design, meet or exceed structural requirements.

Unfortunately, there does not exist a central clearinghouse database for structural design criteria by jurisdiction. For builders and RDPs (Registered Design Professionals) who provide services over more than just limited geographical areas, this would be a tremendous tool.

Now I do have a “hero” building department and will give them kudos here. Kittitas County (Washington) Community Development Services provides a parcel-by-parcel load analysis covering their minimum design requirements (https://www.co.kittitas.wa.us/cds/building/cgdc-form.aspx).

Many building departments have posted climactic design requirements in their websites. When kept up to date, we find these to be quite handy. I would imagine RDPs appreciate availability of this information.

Recently, one of our clients in Wisconsin was facing a challenge – their Building Official would not provide them with minimum loading requirements for their proposed new building! Although rare, I have seen this occur before. In one instance, I had a Building Official refuse to provide accepted loading information. Instead they wanted us to submit engineer sealed plans and then they would tell us if what we had guessed for loading was correct or not!

Why this information was withheld baffles me. In some cases (especially where permits are issued without any sort of structural plan reviews) it could be a permit issuing authority just frankly does not know!

In my humble opinion, an expedient way to streamline permit acquisition processes would be to have readily available design criteria. For sake of public safety, I also feel all building plans not falling under prescriptive code requirements should be produced by a Registered Design Professional.

Converting a Pole Barn to a Residence

Converting a Barn to a Residence
Reader MARK in PORTLAND writes:
“I have a pole barn structure that was converted to a residence without a permit. The slab is 4″ thick with a 4×4 skirt edge around the perimeter. Since the foundation is a pole (pier) system, does the slab edge (non-load bearing) need a thickened lip to extend below the frost line (18″ here)?”
Mike the Pole Barn Guru pole responds:
slab edge insulationWell Mark, as I am sure you are finding out, an entire plethora of issues now exists from the conversion being done without proper permits. Your slab issue just being one of many.
Homes are now required (in most jurisdictions) to meet with energy code requirements. This means you are going to (at the least) have to be adding some insulation below the finished grade of your building. This will eliminate the need to have a thickened slab around the perimeter of your building – which would not only prove to be an added expense, but also a royal pain to install.
I’d approach this challenge with the Frost-Protected Shallow Foundation method, which you can read more about here: https://www.hansenpolebuildings.com/2016/11/frost-protected-shallow-foundations/.
It may take having a RDP (Registered Design Professional – architect or engineer) on board in order to plead your case to the local permitting authorities, who could very well make your immediate future a miserable one should they become angered in regards to the change of use without a permit.
Your building itself could very well pose some other challenges. Most often these come from walls not stiff enough (from a deflection standpoint) to prevent the cracking of any gypsum wallboard surfaces. This is an area which can be looked into by the RDP you are going to hire (please nod your head yes).
Chances are excellent the roof trusses in your building are not designed to support a ceiling load, so you are probably looking at needing an engineered truss repair.
The siding should probably be removed and reinstalled with a housewrap underneath. In the event a dead attic space has been created, the attic area needs to be adequately ventilated to prevent condensation. You can find out more about adequate attic ventilation here: https://www.hansenpolebuildings.com/2012/08/ventilation-blows/.

An Engineer Didn’t Design This Building

If an Engineer Didn’t Structurally Design This Building, Then Who Did?

Many of you have been reading the ongoing and sad saga of Jimmy’s building…..here is the next installment:

Jimmy: “You should go buy a lottery ticket, I asked the builder, he told me only on industrial buildings do they use engineering plans. There is the concrete discs the post sit on, but other than that….it’s just sandy dirt mix supporting the posts.

 Can I take pics or take measurements…and send them or is there somewhere I can tell someone what I’ve got material wise and see if it would work. I think what they’re doing is using the minimum requirements. I originally ordered and paid for the trusses to be built on 2×8 top and bottom chords (on a gentleman’s agreement), when they arrived they were built on 2×6 top and bottom chords, when I contacted the guy he said the truss company made a revision since the attic was going to be for storage and not hay that 2x6s would be suffice for the top and chords. Well that was the straw that broke the camel’s back, so I said either get me the trusses I paid for or give me the difference between the 2×6 and 2×8 trusses, he said I’m not giving you any money. And because it was on a gentleman’s agreement I don’t have a leg to stand on (everything from now on will always be in writing). I asked the builder what he honestly thought, he said the 4×6’s will be fine, but if my father would have went wider than 30 foot he definitely would have gone with 6×6’s. I’m going to follow through on what I added to the original build, but if there’s a way I can prove this guy is building a structurally unsound building I will take him to court.

 What’s your thoughts on concrete? We are planning to insulate the underneath with foam (250 psi) was recommended, and the concrete will be reinforced with fiber, but not with metal screen.”

Dear Jimmy: Please feel free to send any photos or measurements to me for review and I will give you my best honest opinion. My question always is – if an engineer didn’t structurally design this building, then who did?

truss-drawing-150x150The 2×6 top and bottom chords may very well be sufficient, as it will depend as much on the grade of the material used, than just the size. There should have been a sealed truss drawing delivered with the trusses – scan it and send it to me. I spent many years in the truss industry, so if something is amiss, chances are good I will catch it.

Sadly, you already have a building which is structurally unsound. There is no way those “concrete discs” are going to be adequate to prevent your building from settling. It might not happen immediately, but it will happen. A good building, takes a good foundation, it is just this simple.

As to your concrete floor, the best way to get a great floor, is with great site preparation. I’ve written extensively on this topic in the past: https://www.hansenpolebuildings.com/2011/11/site-preparation/. Fibermesh is a product I have used in my own floors and have been pleased with the results. Unless you or someone in the future is going to climate control the building, there is no reason to put insulation under the slab. If you are considering a future with climate control then you should also be reading this article: https://www.hansenpolebuildings.com/2016/08/pex-tubing/
For all you gentle readers I implore you to take to heart the following advice – regardless of whom you invest in a building with:

  1. Never, ever invest in a building which does not have the seal of a Registered Design Professional (RDP – engineer or architect) on the plans. Unless your builder happens to be a RDP, he is just winging it.
  2. Make sure the plans are specific to YOUR building, with exactly the dimensions you ordered, showing your doors. The plans should have your name and the site address on them.
  3. GET IT IN WRITING https://www.hansenpolebuildings.com/2015/04/successful-relationship/

Building Code: Things Which Make My Head Hurt

International Building CodeThe International Building Code (IBC) is the resultant of years of practical experience and sound engineering practice. The authors are a collective group of Building Officials and engineers, whose mission is to protect the safety of those who will be utilizing the structures built under the auspices of the Code. For practical purposes, every word, of every section of the Building Code has been scrutinized, analyzed, hashed over and rehashed to produce what can only be considered as a magnificent work. Even at this, amendments, additions and subtractions are proposed and made or rejected, providing an updated version every three years, which reflects changes which have come about from better science and research.

The Code also allows individual jurisdictions, to make local amendments to the Building Code. Oftentimes this is done without a sound engineering basis, or research to confirm the reasoning behind the amendment(s).

I am going to now pick upon a single permit issuing jurisdiction. This unnamed county has, as is their right, adopted the following:

15.16.060 Post Frame Structures (pole buildings).

A. Post frame structures over twelve hundred (1200) square feet in area shall be designed by a professional, licensed by the State of (Name Withheld) to design such buildings. The licensed professional shall affix his/her certification and signature to the design, including design drawings and details, specifications, and calculations. Any changes to the design, drawings, details, specifications, and calculations during review or construction shall be prepared and certified by the licensed professional designer of record and submitted for approval of the building official prior to incorporating such changes into the work. The minimum design criteria for post frame structures are as follows:

1. Minimum snow load is thirty-five (35) pounds per square foot (PSF). Reductions in live load/snow load are not permitted.

2. The minimum roof purlin dead load is 5 PSF.

3. The maximum total load deflection is:                       

 a. With ceiling: L/240

 b. Without ceiling: L/180

4. The maximum wall wind load deflection is L/120.

We recently had a plan review done, in this county, and the Plans Examiner/Building Inspector threw in this curve:

“Our standard design for accepting engineered plans for pole buildings over 1200 square feet, require that purlins/girts are spaced no more than 24” O.C.  Your plans call for girts spaced at 31 5/8” and purlins at 29 ¼”. “ 

After some discussion with the Plans Examiner the resultant was (as relayed from one of our owners):

They don’t have a 24” oc girt and purlin requirement – just the change to deflection that we looked at. His (building officials) reasoning was ‘experience’ – that engineers use code to under design buildings.

I will only address issues which I feel are either contrary to the Building Code, do not make sense from an engineering standpoint, or do not have a rationale under the Laws of Physics.

Minimum snow load. The Code addresses how to calculate Pf (flat roof snow load) and Ps (sloped roof snow load) based upon Pg (ground snow load) as well as factors such as Is (building importance), Ct (temperature factor – is building heated or not), Cs (sloped roof factor), and Ce (roof wind exposure factor).

Picking an arbitrary roof snow load, leads to the possibility of either gross over design (causing more cost to the building owner) or gross under design (leading to a possible failure).

As espoused by this jurisdiction, a roof for an Essential Facility (think fire station), which is unheated, has a 4/12 slope shingled roof, and is protected from the wind, would have the very same load as a heated storage building with an 8/12 pitch metal roof, which is exposed to the wind. Common sense says this is just not the case.

Minimum roof purlin dead load of 5 psf. The dead load should be set by the RDP (Registered Design Professional – architect or engineer) who designs the building to reflect the actual imposed loads. As 60% of the dead load is used to calculate the wind uplift forces on the building, an arbitrarily high dead load could result in the under design of the connections between purlins and trusses, as well as trusses and columns.  Potentially this could result in a design, by statute, which results in an overstress of these connections.

In reality 2×6 roof purlins at 24 inches on center, supporting a 29 gauge steel roof induce an actual dead load of about 1.5 psf (pounds per square foot). The 5 psf requirement is 333% higher than reality.

The Building Code allows for purlins supporting a light gauge steel roof to have a deflection of L/150, rather than the stiffer L/180. Deflection criteria have nothing to do with the structural integrity of the roof, merely esthetics under high loads.

The Code allows for wall girts supporting light gauge steel siding to have a deflection of L/90, rather than the stiffer L/120, as long as brittle finishes (such as plaster or drywall) are not being supported. Again deflection criteria have nothing to do with the structural integrity of the siding, merely esthetics under high loads.

Creating criteria which are counter to the majority of the jurisdictions in the country only creates confusion for RDPs, building providers and contractors, as well as increasing costs (without reciprocal benefits) to building owners. These criteria appear to be arbitrary and capricious in penalizing post frame construction against other forms of building construction.

If the feeling is the Building Code allows RDPs to under design buildings, then the jurisdiction should move the International Code Committee (along with providing rational proof as to why) to change the IBC. If snow load is their concern, the utilization of higher Pg values than have ever been historically seen (while not a reality), would allow for a uniformity of calculations by registered engineers.