Tag Archives: ground snow load

Building Department Checklist Part I

BUILDING DEPARTMENT CHECKLIST 2020 PART I

I Can Build, I Can Build!

Whoa there Nellie…..before getting all carried away, there are 14 essential questions to have on your Building Department Checklist, in order to ensure structural portions of your new building process goes off without a hitch.  I will cover the first seven today, finishing up tomorrow, so you have a chance to take notes, start your own home file folder of “what to do before I build”.  Careful preparation will be key to having a successful building outcome (whether post frame or some other structural building system).

Provide answers to these questions to your potential building providers!

IMPORTANT SIDE NOTE: Building Departments’ required snow and wind loads are absolute minimums in an attempt to prevent loss of life during extreme events. They are not established to prevent your building from being destroyed. Consider asking your providers for added investment required to increase wind and/or snow loads beyond these minimums.

#1 What are required setbacks from streets, property lines, existing structures, septic systems, etc.?

Seemingly every jurisdiction has its own set of rules when it comes to setbacks. Want to build closer to a property line or existing structure than distance given? Ask about firewalls. If your building includes a firewall, you can often build closer to a property line. Creating an unusable space between your new building and a property line isn’t very practical. Being able to minimize this space could easily offset a small firewall investment. As far as my experience, you cannot dump weather (rain or snow) off a roof onto any neighbor’s lot, or into an alleyway – so keep those factors in mind.

#2 What Building Code will be applicable to this building?

Code is Code, right? Except when it has a “residential” and also has a “building” version and they do not entirely agree with each other.

Also, every three years Building Codes get a rewrite. One might not think there should be many changes. Surprise! With new research even things seemingly as simple as how snow loads are applied to roofs…changes. Obviously important to know what Code version (e.g. 2012, 2015, 2018, 2021) will be used.

 

#3 If building will be in snow country, what is GROUND snow load (abbreviated as Pg)?

Make sure you are clear in asking this question specific to “ground”. When you get to #4, you will see why.  Too many times we’ve had clients who asked their building official what their “snow load” will be, and B.O. (Building Official) replied using whichever value they are used to quoting.  Lost in communication was being specific about “ground” or “roof” snow load.

As well, what snow exposure factor (Ce) applies where a building will be located? Put simply, will the roof be fully exposed to wind from all directions, partially exposed to wind, or sheltered by being located tight in among conifer trees qualifying as obstructions? Right now will be a good time to stand at your proposed building site and take pictures in all four directions, and then getting your B.O. to give their determination of snow exposure factor, based upon these photos.

#4 What is Flat Roof Snow Load (Pf)?

Since 2000, Building Codes are written with flat roof snow load being calculated from ground snow load. Design snow load has become quite a science, taking into account a myriad of variables to arrive with a specific roof load for any given set of circumstances.

Unfortunately, some Building Departments have yet to come to grips with this, so they mandate use of a specified flat roof snow load, ignoring laws of physics.

Make certain to clearly understand information provided by your Building Department in regards to snow loads. Failure to do so could result in an expensive lesson.

#5 What is “Ultimate Design” or Vult wind speed in miles per hour?

Lowest possible Vult wind speed (100 miles per hour) only applies in three possible states – California, Oregon and Washington for Risk Category I structures. Everywhere else has a minimum of 105 mph.  Highest United States requirement of 200 mph for Risk Category III and IV buildings comes along portions of Florida’s coastline (although there are scattered areas nationally defined as “Special Wind Regions).  Don’t assume a friend of yours who lives in your same city has your same wind speed.  City of Tacoma, WA has six different wind speeds within city limits!

Vult and nominal design wind speed (Vasd) are different and an errant choice could result in significant under design (or failure). Make certain to always get Vult values.

#6 What is wind exposure (B, C or D)?

Please Take a few minutes to understand their differences:

(https://www.hansenpolebuildings.com/2012/03/wind-exposure-confusion/).

A Building Department can add hundreds, or even thousands, of dollars to your project cost, by trying to mandate an excessive wind exposure.  Once again, a good place for photographs in all four directions from your building site being shared with your Building Department.  Some jurisdictions “assume” worst case scenarios.  Meaning, your property could very well have all four sides protected and easily “fit” category B wind exposure requirements.  However, your jurisdiction may have their own requirement for every site in their jurisdiction to be wind exposure C, no matter what.  It’s their call.

#7 Are “wind rated” overhead doors required?

Usually this requirements enforcement occurs in hurricane regions. My personal opinion – if buying an overhead door, invest a few extra dollars to get one rated for design wind speeds where your building will be constructed. Truly a “better safe, than sorry” type situation.

I’ve covered seven most important questions for your Building Department Checklist, and they really weren’t so difficult, were they?  Come back tomorrow to find out the last seven!

Getting the Best Deal on Your New Post Frame Building

A price quote is merely a number without a complete understanding of exactly what is or is not included in said quote.

You have requested quotes for your new post frame building from a dozen or more providers and actually gotten four back, even after having to hound all of them for pricing! Frustrating when you are ‘knocking at their door’ trying to spend your cash.

One quote stood out above all others with an exceptional price, so you place your order. Only after “everything” arrives and you try to assemble it do you find out what you thought you bought and what you really purchased are not quite equal.

Disappointing.

If you prefer to read books by starting with the last chapter, you can skip to there to find a solution.

Here are a few points to be aware of:

Will Your Building Meet Minimum Building Code Standards?

Those quotes you got….few, if any, will specify what loads your building are designed for.

Some of them will just be a list of materials! Are they right? Is there even enough there to construct a building?

Every quote should include (at a minimum): engineer sealed plans specific to your building at your site. Complete Building Code information – including Code version (there is a new one every three years), Ground snow load (Pg), Flat roof snow load (Pf), Design wind speed (Vult or Vasd), Wind Exposure (there is a big difference between Exposure B and C) and assumed soil bearing pressures.

You can easily acquire this information for yourself, so you have a point to check from: https://www.hansenpolebuildings.com/2019/01/building-department-checklist-2019-part-1/

If Code information is not on a quote, chuck it.

Do Roof Trusses Quoted Meet Your Needs?

Here is where investing in an engineered building comes into play, as your Engineer of Record (person who seals your building plans) should be reviewing prefabricated roof truss drawings for their adequacy for his or her building.

Planning on supporting a ceiling, either now or at a later date? If so a ceiling load of no less than five pounds per square foot (psf) should be indicated on engineered plans as well as a BCDL (Bottom Chord Dead Load) to match on sealed truss drawings.

At Hansen Pole Buildings, we ran into this situation so often, we decided to upgrade all trusses up to 40 foot clearspan to support a minimum five psf load.

 

How is Roof Steel Condensation Being Controlled? Most providers are not even going to mention this. Most of us prefer it not to rain inside of our new buildings. 

I answer questions online every Monday. Problem/question number one is regarding condensation.

From cheapest up – a Radiant Reflective Barrier (aka bubble wrap – if going this route you only need single bubble, six foot wide rolls with an adhesive pull strip); Integral Condensation Control (https://www.hansenpolebuildings.com/2017/03/integral-condensation-control/); Sheathing with 30# felt; Closed cell spray foam.

Planning on insulating and finishing walls? If not using closed cell spray foam you will want to apply a Weather Resistant Barrier between wall framing and steel siding.

What Written Warranty Comes With Your Building?

If it does, how long does it last? What does it include? When it comes to Post Frame Building kits, Hansen Pole Buildings stands alone with a Limited Lifetime Structural Warranty (https://www.hansenpolebuildings.com/2015/11/pole-building-warranty/).

Are Assembly Instructions Included?

If not, there is plenty left to chance. Hansen Pole Buildings provides a fully illustrated, step-by-step 500 page Construction Manual. And, if you get stuck, there is unlimited FREE Technical Support from people who have actually assembled buildings!

 

How About Your Potential Provider?

How long have they been in business 2 years, 5 years? How about 18 years? How many post frame buildings have they provided? How about roughly 20 thousand buildings located in ALL 50 states!

Here is how to vet any potential provider: https://www.hansenpolebuildings.com/2015/01/pole-building-suppliers/

I promised you a solution (aka Last Chapter of Book)

We are offering to shop for you.  Seriously? Yes! You provide up to three names of competitors to Hansen Buildings, where you can purchase a complete wood framed post frame building kit package, and we will shop them to get quotes for you.

Now we say three, because frankly, some people just are not very prompt or cooperative when it comes to getting back with price quotes.

Why would we do this?  Comparing “apples to apples”, we know our price will beat theirs, every single time. We offer to do this for your peace of mind.   We guarantee all other prices will be higher.  And we will provide you with documentation to prove it!

There is a catch…..before we go shopping you have to place your order for your new Hansen Pole Building kit….. subject to us “proving our point” by going shopping. Your payment to us will not be processed for ten calendar days. Within seven days of order, you’ll have competitive quotes in hand, or our documentation of having hounded them every week day for a week trying to get pricing for you (seriously, if you have to hound someone for a price, what kind of after sale service will you get?). 

After we email you proof, if you seriously want to purchase from one of these competitors, just let us know before ten days pass and we tear everything up and go away friends.

Building Department Checklist 2019 Part 1

BUILDING DEPARTMENT CHECKLIST 2019 PART I

I Can Build, I Can Build!

(First published six years ago, it was more than past time to update to reflect current code requirements!)

Whoa there Nellie…..before getting all carried away, there are 14 essential questions to have on your Building Department Checklist, in order to ensure structural portions of your new building process goes off without a hitch.  I will cover first seven today, finishing up tomorrow, so you have a chance to take notes, start your own home file folder of “what to do before I build”.  Careful preparation will be key to having a successful post frame building outcome.

#1 What are required setbacks from streets, property lines, existing structures, septic systems, etc.?

Seemingly every jurisdiction has its own set of rules when it comes to setbacks. Want to build closer to a property line or existing structure than distance given? Ask about firewalls. If your building includes a firewall, you can often build closer to a property line. Creating an unusable space between your new building and a property line isn’t very practical. Being able to minimize this space could easily offset the small investment of a firewall. As far as my experience, you cannot dump weather (rain or snow) off a roof onto any neighbor’s lot, or into an alleyway – so keep those factors in mind.

#2 What Building Code will be applicable to this building?

Code is Code, right? Except when it has a “residential” and also has a “building” version and they do not entirely agree with each other. IBC (International Building Code) only applies to post frame buildings, not IRC (International Residential Code:

(https://www.hansenpolebuildings.com/2018/10/what-building-code-applies-to-post-frame-construction/).

Also, every three years Building Codes get a rewrite. One might not think there should be many changes. Surprise! With new research even things seemingly as simple as how snow loads are applied to roofs…changes. Obviously important to know what Code version will be used.

#3 If building will be in snow country, what is GROUND snow load (abbreviated as Pg)?

Make sure you are clear in asking this question specific to “ground”. When you get to #4, you will see why.  Too many times we’ve had clients who asked their building official what their “snow load” will be, and B.O. (Building Official) replied using whichever value they are used to quoting.  Lost in communication was being specific about “ground” or “roof” snow load.

As well, what snow exposure factor (Ce) applies where building will be located? Put simply, will the roof be fully exposed to wind from all directions, partially exposed to wind, or sheltered by being located tight in among conifer trees qualifying as obstructions? Right now will be a good time to stand at your proposed building site and take pictures in all four directions, and then getting your B.O. to give their determination of snow exposure factor, based upon these photos.

#4 What is Flat Roof Snow Load (Pf)?

Since 2000, Building Codes are written with flat roof snow load being calculated from ground snow load. Now design snow load has become quite a science, taking into account a myriad of variables to arrive with a specific roof load for any given set of circumstances.

Unfortunately, some Building Departments have yet to come to grips with this, so they mandate use of a specified flat roof snow load, ignoring laws of physics.

Make certain to clearly understand information provided by your Building Department in regards to snow loads. Failure to do so could result in an expensive lesson.

#5 What is “Ultimate Design” or Vult wind speed in miles per hour?

Lowest possible Vult wind speed (100 miles per hour) only applies in three possible states – California, Oregon and Washington for Risk Category I structures. Everywhere else has a minimum of 105 mph.  Highest United States requirement of 200 mph for Risk Category III and IV buildings comes along portions of Florida’s coastline.  Don’t assume a friend of yours who lives in your same city has your same wind speed.  The city of Tacoma, WA has six different wind speeds within city limits!

Vult and nominal design wind speed Vasd are NOT the same thing. Make certain to always get Vult values.

#6 What is wind exposure (B, C or D)?

Take a few minutes to understand the differences:

(https://www.hansenpolebuildings.com/2012/03/wind-exposure-confusion/).

A Building Department can add hundreds, or even thousands, of dollars to your project cost, by trying to mandate an excessive wind exposure.  Once again, a good place for photographs in all four directions from your building site being shared with your Building Department.  Some jurisdictions “assume” worst case scenarios.  Meaning, your property could very well have all four sides protected and easily “fit” category B wind exposure requirements.  However, your jurisdiction may have their own requirement for every site in their jurisdiction to be wind exposure C, no matter what.  It’s their call.

#7 Are “wind rated” overhead doors required?

Usually this requirements enforcement occurs in hurricane regions. My personal opinion – if buying an overhead door, invest a few extra dollars to get one rated for design wind speeds where the building will be constructed. Truly a “better safe, than sorry” type situation.

I’ve covered seven most important questions for your Building Department Checklist, and they really weren’t so difficult, were they?  Come back tomorrow to find out the last seven!

 

Structural Engineering for $400

I’ll take Structural Engineering for $400 Alex

Proper Engineering in post frame construction can not be overlooked.

Alex Trebek has hosted Jeopardy!, the iconic daily syndicated game show, since 1984. With over 7,000 episodes aired, Jeopardy! has won a record 33 Daytime Emmy Awards. Some of you may even have tuned in for an episode or three.

Today’s Answer Is:

Insufficient Data to Provide an Answer

And reader PAUL from FINKSBURG has the question:

“What size header would be required for a 20′ wide overhead garage door placed on the truss bearing wall?”

Okay, enough of my being snarky. The answer to Paul’s question should be clearly indicated on the engineer sealed plans for his building, along with the required connections from truss to header and header to columns.

If somehow the engineer of record overlooked this critical element, he or she should be contacted immediately to provide the missing data. Even worse – maybe an engineer happened to not design the building, in which case CALL ONE NOW.

Whilst this may appear, on the surface to be a simple question, there are a plethora of factors which go into the determination of a structural header to carry roof loads. This would include, but are not limited to:

Pg – the Ground Snow Load

Ce – the Snow Exposure Factor (sites which are open to the wind allow snow to blow off the roof, sites which are protected from the wind keep snow on the roof)

Is – the Snow Load Importance Factor (Risk Category I buildings are a lower hazard to human life, therefore the flat-roof snow load will be reduced)

Ct – the Thermal Factor (heated buildings melt snow off, unheated buildings allow snow to build up)

Pg, Ce, Is and Ct are multiplied together along with 0.7 to determine the Flat-Roof Snow Load (Pf)

But wait, there is more…..

Pf might be further reduced depending upon the roofing material (steel roofing being slick allows snow to slide off quicker), whether or not snow retention systems are present (which hold snow on the roof), as well as the roof slope. Mix them all together and the Sloped Roof Snow Load (Ps) is created.

The dead loads imposed upon the roof also need to be added to the mix – the weights of trusses or rafters, purlins, roof sheathing, insulation supported by the roof system, roofing, truss bracing, ceilings are amongst some of the weighty culprits.

Once all of these contributing factors are combined into a psf (pounds-per-square foot) load, concentrated loads are applied to each of the truss bearing locations along the header – these are based upon ½ of the truss span (including any sidewall overhangs) multiplied by the truss spacing and the applied loads.

Not only does the header need to be verified for adequacy in load carrying capacity, but also limited in deflection. A sagging header can cause unsightly rooflines as well as preventing doors from operating correctly.

Self-engineering is not a good choice – call your engineer….now!

Dear Pole Barn Guru: Why Didn’t You get the Snow Load Right?

Welcome to Ask the Pole Barn Guru – where you can ask questions about building topics, with answers posted on Mondays.  With many questions to answer, please be patient to watch for yours to come up on a future Monday segment.  If you want a quick answer, please be sure to answer with a “reply-able” email address.

Email all questions to: PoleBarnGuru@HansenPoleBuildings.com

DEAR POLE BARN GURU: I recently ordered a pole building kit package. The agreed snow load was 35. A minimum of 34 is required in our area. The calculations supplied are for 28, not 34. So now we are out another $800 and

back to square 2.

What can be done, and how fast? SNOWING IN SNOHOMISH

DEAR SNOWING: We’d all like to believe Building Department Plans Examiners are infallible. The reality is, the IBC (International Building Code) is a huge and complex document, which is further complicated by its references to numerous other outside documents.                  

The agreed upon snow load which you purchased, was 35 pounds per square foot (psf) as a GROUND SNOW LOAD (or Pg). The Code references a document called ASCE 7-10 (for the 2012 version of the Code). ASCE 7-10 gives the formula to convert Pg to flat roof snow load (Pf). This formula takes into account factors such as Building Importance, if Building is heated or not and the roof’s exposure to the wind. The roofing material also comes into play with the heating or not of the building.

 Pf is also adjusted for roof slope, to get to the design sloped roof snow load (Ps).

 In your particular case, our office made a call to your plans examiner who has now been happily educated.

 For further reading on this subject, please see the article I wrote for Structural Building Components magazine: https://sbcmag.info/article/2011/it-isnt-your-grandpas-barn-tips-technicians-designing-post-frame-trusses

DEAR POLE BARN GURU: I have an old metal barn that needs new doors and hardware. A pair of sliding doors that are each 10′ wide by 14′ tall. We had a storm that blew them off and damaged the tracks and channels. We live in Fowler, Colorado. Do you have a dealer here in Colorado? Or can we get them from you to install ourselves? Any information would be appreciated. CAUGHT IN COLORADO

 DEAR CAUGHT: Sliding doors can be a challenge in wind storms. If they are not correctly designed, installed, or kept closed and latched during high winds, they can all too easily end up as an unusable pile of rubbish. Sliding door frames which are built either partially or all from wood, are especially susceptible to failure under load.

 Hansen Pole Buildings provides sliding door systems and components direct to builders and end users in all 50 states. The doors are designed for the average individual to successfully assemble and install their own sliding doors, by following the detailed step-by-step instructions.

Call us and we will get you started on the path to replacing those doors.

DEAR POLE BARN GURU: Hello, I am helping a friend build and install sliding doors on his pole building. The building is otherwise complete. The door openings are pretty much ready to go as I can see. They are framed in and the upper track is installed. So here I come with a pile of steel siding, steel studs, track for SIDS and button of doors, rollers (pendant) and screws… The instructions he has are very vague. Can you provide me with any plans, prints, instructions of any kind please? Also a photo or diagram of what the finished product should look like?

They have a binder with instructions that supposedly came with the kit and your logo on the front of it. I’m not there at this time so if you need the model name/# I can send it to you this afternoon when I get there.  WONDERING IN WASHINGTON

DEAR WONDERING: While our sliding door systems are relatively simple for the average individual to install – having the detailed step-by-step instructions included in our Construction Guide, in hand would be a serious assist.

 The manual devotes 18 pages which include actual photos, as well as diagrams showing how to properly (as well as most quickly) assemble and install each component. Check the manual for these pages and then let me know if you still need help. Often people think the instructions come with the door and we’ve found having them in the Construction Guide makes them easier to find.

Things You Never Wanted to Know About Snow Load

Yes I know, it is white (at least it starts out that way).

From a design standpoint there are lots of things to know about snow loads.

Cautionary Warning: The information contained herein is fairly technical in nature. We use ALL of this information in the design of your new Hansen Pole Building. Some clients will think this is all very cool, for others, it may cause your head to explode. I’ve been waiting three decades to pass along this information to a client, as I’ve always felt the understanding of it is pretty impressive.

1.  GROUND SNOW LOAD (otherwise known as Pg). This is based upon a once in fifty year (probability of event greater than design loads happening is 2% in any given year). The use of unrealistically high Pg values causes issues with the design for drifting snow.

The International Code specifies design snow loads are to be determined according to Section 7 of a document called ASCE 7. This document provides for all roof snow loads to be calculated from ground snow loads, however not every Building Department follows this procedure. When discussing snow load with anyone, it is crucial to have a clear understanding as to if the load is a ground or flat roof snow load.

Pf is FLAT ROOF SNOW LOAD – If, as a consumer, your concern is snowfall and you want to upgrade the ability of your building to carry it, THIS is the value to increase. Often changes of five or 10 pounds per square foot result in minimal differences in cost.

Pg is converted to Pf by this formula:

0.7 X Ce X Ct X Is X Pg = Pf

2. Ce is the wind exposure factor for roofs.

For an Exposure B or C for Wind; Fully Exposed = 0.9; Partially Exposed = 1.0; for fully sheltered (e.g. nestled in tightly amongst conifer trees as an example) Exposure B = 1.2, Exposure C = 1.1 (how you could have Exposure C and fully sheltered is beyond me)

We use partially Exposed (Ce = 1.0 as a default)

3. Ct is the effect of temperature (building heating), where:

Ct = 1.0 for heated structures (climate controlled)

Ct = 1.1 for Structures kept just above freezing and others with cold, ventilated roofs in which the thermal resistance (R-value) between the ventilated space and the heated space exceeds 25h – ft^2 – degreesF/Btu

Ct = 1.2 Unheated

We use Ct = 1.2 as the default value

Most truss designers will use a Ct value of 1.0 or 1.1 in their designs. This results in a decrease in the ability of the roof to carry snow loads. These values should only be used when appropriate.

4. “Is” is the IMPORTANCE FACTOR

ASCE I is a structure which is a low hazard to life in the event of a failure. Is = 0.87

ASCE II residences and frequently occupied commercial buildings (a warehouse or storage building is probably ASCE I) Is = 1.0

ASCE III Is = 1.1

ASCE IV Is = 1.2 (these are “essential” essential facilities – police/fire stations, hospitals)

5. There is also a Minimum Roof Live Load (known as Lr) of 20 psf (defined by Code) (psf = pounds per square foot) which accounts for weights such as construction loads, when Pg values are very low.

Lr is adjusted based upon the area the roof member supports and can be as low as 12 psf, in cases where a roof member supports over 600 square feet of area.

Doing the math, it would be unusual, using the laws of physics, for Pf to be greater than Pg – however, some jurisdictions have established Lr values which defy the laws of physics (e.g. State of Oregon, where most of the state has a minimum Lr of 25 psf – exceptions being some locations along the coast, where it is 20).

From Pf, Pr (Pressure on the roof) values are calculated depending upon whether the roof is a slippery surface or not, whether building is heated or not and the slope of the roof.

The Top Chord Live Load (TCLL) of any roof trusses will be the greater of Pr or Lr.

6. Duration of Load (DOL) for Snow is typically 1.15. DOL can play a part in some snow areas, where the Building Official (BO) has made the determination snow will remain upon the roof for extended time periods. Some Examples of this include Higher elevations in Utah and Kittitas County, WA where the BO has declared DOL = 1.0. In areas with little or no snowfall (where Lr > Pr) DOL = 1.25.

Yes, I know this is a lot of stuff to carry around in your head.  Trust me, I know all too well, and my character analysis consistently reads “does not like numbers”!  All these numbers and “code requirements” are why we not only ask, but insist you must take the page of our quote with the Design Criteria to your building department to get their blessing on it, and ask if there is anything else they require.  With over 7000 building departments in the U.S., it would be the greatest feat on earth if we could keep up with all of them, and which ones change on any given day. My last caution is to be careful when asking your building department about snow load.  Be sure you keep “roof” and “ground” snow loads separate.  Because when it comes to getting your building designed, priced and finally plans signed off by your building department, there is a difference!