How often are y’all doing any calcs for single-family residential? 7

[ANE91]

Had a friendly lunch with some sorta-competitors in my market who were very frank about never doing calcs for their work. Work ranges from design to repairs/retrofits, almost all wood. Are they messing with me or what? Obviously, a practitioner can output more work without pausing to do any pesky analysis.

 

[DoubleStud]

I do calc but I dont submit them. I have the calculation files but I dont create a calculation bundle with title block and table of content. The counties don't require the calcs. They just want stamped drawings.

 

[milkshakelake]

I am not confident in my wood abilities, so I end up calculating a lot of it in terms of gravity (I'm a bit more confident in lateral, having done like 250 apartments in a past job and spending a ton of time on it). I'm far more confident in concrete and cold-formed steel, for which I've made quick standards and reference tables that work for my size of buildings. I think the number of calculations comes down to AHJ requirements, the general culture of that area, and how confident you are in fulfilling it. I'm not that confident.

 

[Aesur]

We calculate and submit almost every gravity member and shear walls and diaphragms, but do put "B1 sim" etc.. where we can, typically this helps with beams or lintels mostly. The jurisdictions where we design high end houses scrutinize the calculations more for houses more than they do commercial it seems many times.

 

[SinStrucEng]

I do all critical member calculations (beams/girders/headers/lintels), tall wall framing, masonry, as well as shear walls, but residential foundation design is "standardized" where I am - provided that the bearing capacity and soil specs are typical and not odd/special. We aren't required to submit calcs in our jurisdiction.

For what it's worth there are many smaller residential jobs that I've done where calcs truly were not necessary. These are often additions or something on a lesser scale where designers (not licensed architects or engineers) could have done the work but the homeowners simply preferred an engineer's input/review.

 

[ANE91]

For what it's worth there are many smaller residential jobs that I've done where calcs truly were not necessary. These are often additions or something on a lesser scale where designers (not licensed architects or engineers) could have done the work but the homeowners simply preferred an engineer's input/review.

Just about everything that goes up in my market is done without an engineer/architect. Builders here have gotten very good at toeing the IRC.

I only get called when it goes sideways.

 

[JoshPlumSE]

My old boss would look at the project (which was similar enough to previous projects he'd done in the past) and say something like, "This is what we're going to do. Just add in some sister joists for the increased weight. Pretty sure that will be the easiest solution."

We still did the calcs, but he was almost always right. If it didn't work out, I'd tell him and we'd take care of it.... His "engineering intuition", based on years of experience with similar projects, had an incredible batting average.

 

[skeletron]

Yikes! Surprised to see lots admit they eyeball or otherwise don't document any analysis. In my jurisdiction, this would almost be a sure sentence to spending the rest of your days as a barista with a neat little $10k penalty for the association's legal party...er, department. That being said, I'm also not surprised given that wood is almost purely synonymous with prescriptive design and constructed by labour that makes sure you-know-that-they-know it'll work 'cause wood is strong.

Formal calculation packages are rarely requested for submittals in my jurisdiction. A formal package to me is something organized in one document with a cover sheet, TOC, or otherwise linear narrative to the design. An informal package to me is a bunch of labelled PDFs that sit in a folder and could be sent to an interested part or investigator upon request. It is good practice (and my own baseline) to keep a record of the critical bits and I typically do the informal method. For me this includes the loads used, member sizing generally done with envelope sizing, basic foundation check, lateral design showing your nails and hold-downs meet the force effect requirements. It is debatable whether designers go a step further and do the lateral drift calculation for simple residential. My experience is that most don't because it's not something that you can eyeball.

I honestly wish I didn't feel as morally compelled to meet the letter of the documented law, but I would rather stay in the legit game for another couple of decades. And, I think that is how you develop engineering judgement/intuition/eyeballs...repetition and memory.

 

[GaStruct]

In most states the IRC is the adopted code and therefore IS the letter of the law. So, you can rest assured that following it satisfies your morals where the residence falls under the IRC provisions.

When the IRC applies, you can and absolutely should use it where applicable. Lateral being the #1 thing to use it for. There is no reason to riddle a house with shear walls and moment frames if it works prescriptively per the code. This only adds unnecessary cost and contributes to the perception that our profession overengineers solutions

Additionally, I can just about guarantee that the houses that get a SW design have more diaphragm discontinuities and load path breaks than you can count. How effective are those shear walls if the load path is broken? In SFR construction, designing or correctly building an irregular diaphragm is impractical. Even in multi-family projects, especially on the East Coast, it’s rarely done. Prescriptive is your best friend.

If you're not yet comfortable determining at first glance whether a residence will meet prescriptive lateral requirements or needs additional shear walls, that's okay - you'll develop that skill with time and experience.

 

[Eng16080]

If you're not yet comfortable determining at first glance whether a residence will meet prescriptive lateral requirements or needs additional shear walls, that's okay - you'll develop that skill with time and experience.

No problem with this approach if it's somehow backed by a rational analysis. What I see all too often is that the "experience" is gained by providing a questionable design and suffering zero consequences. Then using that as justification.

I hear all too often stuff like:

"Houses don't just fall over"

"We don't get earthquakes here"

Blah blah blah. Some of these engineers act more like your local builder that's "been doin this for 30 years"

 

[JoshPlumSE]

What I see all too often is that the "experience" is gained by providing a questionable design and suffering zero consequences. Then using that as justification.

A friend of mine (California SE) was brought in by a neighbor to take a look at a pissing contest between the contractor and engineer. This was +20 years ago in the post Northridge era.... 1997 UBC or very early days of the IBC.

The contractor was complaining to the owner about the engineer. Doing one of those, "I've been doing in this for 30 years and I've never done what this guy is asking for."

My friend looked at it. Thought to herself, maybe it's a little conservative. But, told her neighbor, "Look, the contractor has probably been doing this for 30 years. That's true. But, in Northridge, this type of system collapsed and people died.... As a result, the codes have changed. He'll have to get used to this if he continues to do this type of work".