Traditional building for owner builders and our "gut feelings"

[John Raabe]

While this site has valuable information on code rules and when you need to have an engineer involved in evaluating you house plans, most of the traditional and historic houses that have stood the test of time were not built that way. They did not use professionals and were built with structural rules of thumb and the builders intuitive experience.

Sometimes our "gut feelings" are able to tap into information that can be right in ways that go beyond the rational approach. Engineers and most professionals break things down into component parts that can then be modeled with mathematical tools. This isolates the studied elements from the rest of the structure. Intuitive thinking is usually more inclusive of the whole building.

Here is an interesting article on this topic:

http://www.rationaloptimist.com/blog/when-less-means-more

[speedfunk]

Very nice. 

[Don_P]

There is a slight difference. I believe you all are advocating the patient make the judgement call that the doctor is making in the article. Although I do firmly believe I could drive a semi or fly a plane by "gut feeling" there is probably some underlying reason behind a good number of the rules that are in place. In the case of houses our gut feelings about strength of materials gets pretty sketchy about the time that we can't break it over our knee. I've seen girders attempted out of everything imaginable, there is no innate common sense about these things. What you don't see in the traditional homes catagory is all the houses that didn't make it due to dead reckoning. If you first know the rules and reasons and then choose to make some adjustments then the argument has merit. As an excuse for laziness it gets plenty of mileage.

[John Raabe]

Trustable gut feelings come from experience. Without experience you should not blindly put your faith in vague hunches.

The master builders who built the historical buildings we treasure were well experienced (they had put in their 10,000 hours). They weren't born knowing how to do this.

It is quite possible to build dangerous buildings (though it takes genuine stupidity) and it's even easier to build buildings that will need later repairs (some not very much later).

If you don't have trustable experience, work with someone who does. A professional expert (architect or engineer) will know how to use the current standard models to rationally analyze the structure. This will likely satisfy the authorities but does not totally protect against stupidity. Any experienced builder will likely have colorful stories to illustrate this point.

[carroll]

Stories abound of mistakes:  I was on a steel-building crew for a few years, and one of the foremen left a cap off of a few roof vents one night;  you can guess what happened.  Torrential rains came (great timing, right), flooded the floor beneath, which caused myriad problems underneath them -- it was the typical "cluster@$#%$" -- foreman got fired over that one!

A few years later, they'd put up the whole metal skeleton of a two story big building for a  company, but hadn't gone back and tightened down ALL of the bolts (or so I heard -- wasn't with them at the time);  tremendous wind came up, blew the whole thing over!  That was considered an 'act of God' so no one got fired over that one . . . .  Everyone was marveling how God saved the foreman's you-know-what  . . . .!

Stupidity can intercede even with engineered marvels . .  . .

[MountainDon]

Some "gut feelings" do come from within. The fear of fire for example. Pretty much anyone knows to run away from a wildfire for example. But sometimes, experience dictates differently.

During the dry summer of 1949 a ferocious prairie fire broke out in the Mann Gulch river valley in Montana. The fire-fighters who had been parachuted in to fight it, known as smokejumpers, were walking down a very steep gulch on the other side of the river when all of a sudden the wind abruptly shifted and the fire changed direction and blew across the river. The smokejumpers started to run back up the hill - one of the most basic instincts we have is to run from fires.

But fires tend to move very fast uphill because heat rises. Their leader, Wag Dodge, quickly realized that there was no way they were going to outrun the flames and ordered them to stand still. Needless to say they all thought he was committing suicide and carried on running.

Yet Dodge, who had nine years experience as a smokejumper, realized his fear was going to lead him to his death. In that moment he invented what is now known as an escape fire, when you light the ground in front of you and lie down in the burnt embers waiting for the fire to pass over you. He emerged unscathed, while 13 of his 15 men died.

None of us come with a built in trustworthy sense of strength of materials, though. That is learned from books or reliable internet sites and better yet from books and work experience.

[MushCreek]

Gut feelings that come from years of familiarity are what I would call educated guesses. As an example: I've been designing and building plastic injection molds for 35 years. I had the opportunity to design a mold with my son, a newly minted mechanical engineer. With no experience, he didn't know where to start, so I threw some numbers out, which he then crunched (actually, the software did the number crunching). Turns out- no surprise- that my numbers were very good, and the design stood. I can tell at a glance whether something (particularly metals) will be strong enough and last long enough. When it comes to wood, I tend to over-build, not necessarily a bad thing. To me, code is minimum, and I always exceed it. When it comes to non-prescriptive building, I defer to the engineers, and then bump that up to the next increment. If the plan calls for such-and-such an engineered truss on 16" centers, I'll either go up a size on the truss, or put them on 12" centers. Wasteful? A bit, perhaps, but the results are solid. When I have my roof trusses made, I simply increase the load rating desired.

All that being said- I've seen some very lightly built structures that have nonetheless withstood the years. My mother's 125 y/o house in CT was way under code minimum, but it's still there. My brother and I noticed that the kitchen floor was sagging a bit, and went down to the basement to investigate. The floor joists were 2X6's on 24" centers, spanning about 12'. Several of them were rot and insect damaged, causing the floor to sag. We sistered them up with PT 2X8's, and jacked the floor back into place with lally columns. This house has withstood 125 years of use, heavy snow, and the occasional hurricane.

Toolmakers will drive regular builders crazy. To me, everything not only has to be overbuilt, but perfectly level, plumb, and square. I routinely work to .0001" (one ten-thousandth of an inch), so to me, 1/8" is a football field!

[OlJarhead]

I would add that inspectors and engineers etc also are influenced by politics.  Something the gut is not.

How do I mean?  Well if the inspector is a state or county (etc) inspector then he must abide by the law of the state/county etc and not physics.  So, if an R19 floor will provide all the insulation you would ever need and the 2x6 joist all the strength you will need according to the span you have then he can't go with physics and approve it but rather must go with politics and insist on R38 and 2x12's.

Another example is 2x4 walls.  I live in a house that is now 59 years old.  It has 2x4 walls on the ground floor (original) and 2x6 on the addition out back that I put in...only thing?  It now also has a 2nd floor standing on top of those 2x4 walls which are obliviously strong enough to hold it.

Point?  I can't build a home with 2x4 walls if I want to.  Why?  Politics.

[Don_P]

The gut is certainly influenced by politics, you've given shining examples. Just like any good politician, I've seen plenty of peoples logs and lumber get to be just as strong as the math says it needs to be. Structurally I agree with code math. Also called accepted engineering practice, or rational design. This is the agreed upon physics in the real world and the limits of what an inspector can require. This then tempers ones experience. Through time my body has become attuned to the reverberations of an l/360 floor, with a simple heeldrop I have a pretty good idea as to whether to check the floor joists. My gut is politic in that regard. 

In Springfield IL I was required to use a minimum of 2x10 treated joists under any exterior porch, deck, or stoop. It is the only time I've really been required to do something structurally that was intentionally outside of the agreed upon physics. We can take the math to the span tables, they are right. Nothing structurally in the code prohibits 2 story 2x4 construction.

If your gut is correctly tuned, an 8' 2x4 "column".... stud, etc, should be giving you pause. It is stepping on one of those physical lines, the column slenderness ratio. A point where your gut should be warning you of buckling danger. The code allows a 2x4 stud even though the physics doesn't because we know empirically that it works. Looking at that dimension and length, that geometry should be triggering pause that you then can rationally step through. My guess is that no one here has ever experienced a tremor from their gut on this.
http://www.wikiengineer.com/Structural/ColumnStabilityFactor

Do you think that is one lone instance?

We cite our guts, our smarts and the knowledge of ancient builders as if even modern novices are above that level. The old master builders were a good bit better than that. I'm not here to rain on anyone's parade but certain assumed knowledge is not there and it is unsafe to pretend that it is.

[MountainDon]

About 2x4 walls. The reason you can't use 2x4 for walls has nothing to do with strength. It is solely the need to meet a certain level of thermal resistance. The least expensive way to do that is 2x6 walls. You could do it with 2x4 and external rigid foam sheets. 

That is another government rule. Politically driven I suppose. There are benefits to my wallet though. 

[MikeC]

In this area (N ID) I'm amazed at the number of newish code built commercial buildings which collapse from snow or wind loads, yet the 100 year old commercial structures are unaffected in the same conditions.

Something doesn't seem quite right.

[Sassy]

The building inspection dept building in Mariposa (approx 15 y/o - millions of $$$) flooded out 5 yrs ago when we got a lot of rain (at that time the bldgs were only 10 yrs).

The carport for the car inspection station at the DMV started falling down w/a light snow...  this too was engineered & built to "code."

The old courthouse is still standing & it was built in 1851...     But the city planners want to spend some more of the non-existent money & build a new courthouse 

[SouthernTier]

John references in passing the "10,000 hour rule".  This is the rule of thumb (which probably doesn't always apply) that it takes 10,000 hours of practice to become an expert in anything.  It was popularized in Malcolm Gladwell's book Outliers.  Here is a reference to it.

I think what people are referring to regarding the buildings from the 1800's and whatnot that are still standing are the products of people who had the ~10,000 hour experience.  They may not have had the PE license, but they had something better, experience.

What code and structural calculations are good for is this: people like me and lots of others who frequent this site who *don't* have the 10,000 hour experience.  Yet we still want to build a cabin.  Fortunately, folks like us can still build a cabin because there are these ways developed to know when something will reliably work over the long term, namely things like span tables, and building codes.

These have limitations.  For example, they have to apply to the generic case and try to anticipate all sorts of applications, and thus for many applications, are overkill.  As noted above, they work through looking are discrete components of the system (beacuse they don't "know" what the overall system is), and this always provides an incomplete view.  Another limitation is that some parts of the code aren't related to whether it will work, but for other reasons (i.e. energy efficiency, etc.).

But considering I don't have the luxury of doing the 10,000-hour apprenticeship before I build my cabin, I am glad there are these resources out there, otherwise, things could go to hell quickly.

[alex trent]

Pretty much a tradeoff. I could never have done my place (actually not done yet but the planning is, which is the most important part) without the advice on here. This advice is most always "code based". I know that in some ways I am way overbuilt, but other things I would have done would have been a disaster, even though they looked right...and sometimes had the blessing of a "builder". And as I read things on the web, I see a lot of bad advice that could get a person in trouble if they just went with it.

So, while I look  at some things on my house and pretty much know I am 2x on it, I worry less because i know I am not 0.5 x on something that can cause problems.  I wake up at night worrying about the 0.5x part!

[MountainDon]

Sorry.... I was quoting something squirl posted and screwed up and deleted it. 

I am quite embarrassed about that.

[Squirl]

In this area (N ID) I'm amazed at the number of newish code built commercial buildings which collapse from snow or wind loads, yet the 100 year old commercial structures are unaffected in the same conditions.

Something doesn't seem quite right.

Because the ones that were built poorly collapsed or were demolished 99 years ago.

I have done a lot of renovations on 100+ year old houses where a lot of hands did what "felt right" to fix things without knowledge or experience.  It worked too, until it failed.  Then I had to fix it and curse why people did it that way.  Codes and laws are just another publicly available form of knowledge that can be found in most books and as second had to good professionals.  The difference is they don't have to look it up or find a code section, they have the experience to know.


Sadly that experience is largely gone in many areas.


No worries.  I still had it open in another window.

[MountainDon]

No worries.  I still had it open in another window.

God Bless You

  It worked too, until it failed. 

Words to remember.

[UK4X4]

In order for "gut feelings" to work

there has to be either a level of experience or knowledge

if either of those are lacking a practical test can also be carried out.

ie I think that beam can hold X weight

two blocks on the ground - add beam and a centralised water container - work in kilo's and its a litre of water per kilo
fill to required weighting and measure the movement if any.

As far as succesfull old buildings go - like many have mentioned the failed ones are'nt arround anymore !

[OlJarhead]

Man is not perfect.

Codes are made by man.

Therefore, codes can not be perfect.

Something to remember is that just because it is a law, does not make it rational/logical.

For example, code says that a cabin in some parts of this country MUST have a 2x12 floor and that if said cabin does not have a septic tank attached to it then said cabin owner must destroy his/her well.

Yes some codes, maybe even most of them, for buildings have good and logical reasons for being, however that does not mean all codes are so.  Again, 2x4 walls are fine but they are no longer 'code' -- this is politics influencing code.

[MountainDon]

Again, 2x4 walls are fine but they are no longer 'code' -- this is politics influencing code.

Let's be fair and correct about that, or show me a code that says 2x4 are not permissible for wall studs.

Under the latest IRC (2009 as used by WA state and many others) 2x4's are fine for wall studs, even two story residential. See IRC Table 602.3(5)
http://publicecodes.citation.com/icod/irc/2012/icod_irc_2012_6_sec002_par006.htm
Scroll down to the table...

There are some WA state ammendments but none address the size of wall studs.

Now then, a builder might have to use 2x6 studs to reach the minimum required wall insulation if they want to use batts in the walls. However, there are other choices. Rigid foam can be applied on the exterior, for example and can result in better insulation than filling wall cavities with fiberglass.. That's a different code and it does not state that 2x4 wall studs are not allowed; it simply states that so much insulation value is needed.

I'm being a stickler, a pain in the rear on this because the statement above about 2x4's not being permitted is not true ans this is exactly how false information is spread and becomes "truth".

[OlJarhead]

Let's be fair and correct about that, or show me a code that says 2x4 are not permissible for wall studs.

Under the latest IRC (2009 as used by WA state and many others) 2x4's are fine for wall studs, even two story residential. See IRC Table 602.3(5)
http://publicecodes.citation.com/icod/irc/2012/icod_irc_2012_6_sec002_par006.htm
Scroll down to the table...

There are some WA state ammendments but none address the size of wall studs.

Now then, a builder might have to use 2x6 studs to reach the minimum required wall insulation if they want to use batts in the walls. However, there are other choices. Rigid foam can be applied on the exterior, for example and can result in better insulation than filling wall cavities with fiberglass.. That's a different code and it does not state that 2x4 wall studs are not allowed; it simply states that so much insulation value is needed.

I'm being a stickler, a pain in the rear on this because the statement above about 2x4's not being permitted is not true ans this is exactly how false information is spread and becomes "truth".

Interesting post and I suppose you may even be able to convince the local inspector of that.  But therein lays the rub, the local inspect.

I've actually had a local inspector tell me I had to use 2x6 exterior wall studs.  Period.

Yes I'm sure that if I made the right argument (perhaps with a lawyer behind me) I could convince him otherwise but have you ever actually tried to do that?

Just as I had a local inspector tell me that I had to have an R38 floor in my cabin....best not to argue with them.

I might also add that my wife used to run a home daycare and the jack booted thugs who did inspections used to find her in violation of certain codes (RCW's).  I'd look them up, print them out and sit there with them (and her) and tell them that what I read is not what they are claiming (like a code which says the cleanliness of the home will be determined by the home owner which they used to claim you had to steam clean your rug once a month....yes reread that if need be).  Their answer:  we are here to interpret the code and we do not interpret it that way.

My wife no longer runs a daycare and they continue to abuse people with their interpretation of the codes.

Trust me on this one, your inspector, should he or she be on of those jack booted thugs, will decide what the code means as written and you are free to fight the state in court just so you understand that the attorney general is on the side of the state.

[Don_P]

I've actually had a local inspector tell me I had to use 2x6 exterior wall studs.  Period.

Yes I'm sure that if I made the right argument (perhaps with a lawyer behind me) I could convince him otherwise but have you ever actually tried to do that?

Just as I had a local inspector tell me that I had to have an R38 floor in my cabin....best not to argue with them.

In your case neither party knew the law, so it just becomes a bluster match. Move beyond that. If there is a violation I don't understand I'll ask for a cite from the codebook. No cite, no violation. Then we discuss. We do interpret things differently and I'll normally voice my interp and listen with an open mind to his. An open mind...
If I seriously disagree with his interpretation I have no problem going up the chain, and have. These guys are hired by us to enforce our laws. It isn't the cops fault you don't agree with the speed limit. A true thug in that position isn't going to win with me nor should he with anyone, he'll become a special project  .

I've sat down with the codebook and the inspector many times. Last year on one job he approved things for an owner builder I was helping that I refused to do. It caused a bit of stress with the client but everyone was happy in the end. I was looking out for their safety. In one case it was the laws of physics that were being broken, in the other the laws of man, a set of stairs that were wrong... I agree with that law. By the time I sat down with the inspector he had found that stair code but wasn't going to say anything since he had given the homeowner an interpretation.

I don't normally have issues with inspectors and don't build for them. You all are arguing over the height of the low bar. That isn't to say I don't miss the mark, on this house the mason and I spent a day tearing out and reworking part of the fireplace and chimney... and I agreed with his interpretation. This requires that you detach yourself, be rational, logical and honest.

50 work weeks /year X 40hrs/week=2000 hrs. 5 years = 10,000 hrs.  I don't believe I'd leave a helper with 5 years experience alone on a job for long.

I've seen folks wanting to be able to use the combined strength of all the parts to develop a load path rather than being able to point to individual members and size them to take the load. A good bit of the collapses I've seen over the past few years are in modern engineered post frame. One of the professors that came up with the formulas that allow post frame to combine the skin with the frame in calculations said that post frame would be dead if we hadn't figured out how to apply those combined loads. I'm guessing that we will see some refinements as time goes by. And you want to do that from your gut? 

Trust me on this one, your inspector, should he or she be on of those jack booted thugs, will decide what the code means as written and you are free to fight the state in court just so you understand that the attorney general is on the side of the state.

On shadings of gray, possibly. On clearcut law such as the examples given, the board of appeals would probably not bother to hear it, they would simply give the inspector a dope slap. We aren't even close to court yet.

[flyingvan]

I think the tendency for us amateurs is to overbuild.  If you're building one place, the cost of framing with 2x6's instead of 2x4's is negligible.  If you're building 2,000 units, all the same, saving the $300 on the smaller lumber adds up.  Engineers can design structures to use the minimal size materials to meet structural and energy standards.  When people are going to take on a life-altering project life owner/builder, and have so much of yourself tied up in it, having it collapse would be catastrophic on many levels.

[Don_P]

Some overbuild, but then I've been under houses that were wired with cheap extension cords. Amatuers are all over the road. some do better and more thorough work than a pro, others are a clear and present danger to themselves and others. People tend to balk at spending money for basic life safety... notice the number of people that will do anything rather than build a real foundation under their home. Have you heard the difference between someone who learns to pick on their own and someone who has had lessons. A few self taught pickers are flat out awesome, but the majority have obvious holes in their skills. It is the weak link that pops.

[Squirl]

This reminds me of a conversation I had with my inspector on my current project.  I am a complete amateur.  I do this as a hobby and not as a profession.  I submitted my application for a 20 ft wide building with 2x12s at 12" o/c.  He wrote back to put in a center beam, and issued the permit.  I was completing the foundation and getting to the floor and I had the discussion with him.  I pointed to the code charts that it was within code.  I pointed out that my original design was even within code to the next higher deflection value of 480.  He nods his head and said that I could do it if I wanted, he wasn't going to stop me.  He said it is a suggestion because even though all the charts say it, I am still going to have some bounce or vibration in the floor at that distance, and I would feel it over time.  I thought about it.  He has been a licensed engineer designing and building structures for 20-30 years.  For the past 5 years he has been inspecting buildings from start to finish, seeing what works and what doesn't. He even took the time to explain some examples of where he had seen this done and how the house performed after it was built. I am going with his gut and putting in a center beam.  I can point to charts all day that tell me it will work, I just don't have that same life experience of how wood performs over 30 plus years to make that gut call.