I've got bad news and worse news. First the bad. The article that you were referring to mentions the likely superiority of wood that was used near the "turn of the century". The writer apparently forgot that we've turned another century mark since then. While it's true that most of the framing was done with the thought of when in doubt make it stout, and the framing members' nominal and actual sizes were much closer. That meaning a 2 X 4 used to measure much closer to 2" by 4", whereas today their actual dimensions are typically closer to 1 1/2" by 3 1/2" due to the finishing now done at the mills where the boards are cut. The older growth lumber was also cut differently and from larger trees. Without going even further over the edge with comparisons of quarter sawn boards vs. flat sawn, etc. suffice it to say that the old lumber was just better, but that doesn't mean that the old engineering was also better.
One of the most common causes of old house floor deflection, sagging floors, is also caused by an old misconception where wider sections of wood were sometimes used in place of deeper sections of wood. That is a pair of 2X6's might be used in place of a single 2x10. Again, there is a difference, but it's not necessary to understand for the purposes of this discussion. What is necessary is that you understand that the time that this happened was between the Spanish American War and the Great War. We aren't Europe with 1,000 year old cathedrals but we have been building wood frame houses here for quite some time now.
And speaking of framing, don't take a few span tables and engineering equations and think that you're going to figure out your home's floor load designs. There are a multitude of other factors that come into play when calculating loads. Was the house balloon framed or stacked, were the joists ends given a fire cut, did the contractor get away with using a #2 or #3 grade larch rather than a #1 fir, were the doubled joists directly under the load above or offset for the plumber, did that cable guy destroy the integrity of your joists buy drilling 1 1/2" holes for his coax 'cuz that was the last sharp bit that he had on his truck that day?
As for homes built 20 years ago...well you're right on the cusp of a period when some of the shabbiest crap in America was passed off as home construction. Being in Virginia you're doubtless familiar with the fact that folks who live on the Eastern Shore of the DelMarVa Penninsula are a little different from those on the more urban western shore. Specifically here this refers to the fact that many jurisdictions over there (I'm on the western shore), didn't even adopt modern building codes until this century. Even here we have significant differences between brick shell 200 year old row houses and WW II era pallet shacks that were thrown up for the hordes of West Virginia miners that moved here to build airplanes during the war. Many of the houses along the Chesapeake are updates of updates of updates that were originally summer screen porch cottages people used to escape the city heat. Looking under these usually reveals extensive termite damage and some very creative interpretations of structural engineering and design.
Older is not better, but yet neither is modern. Most of the East coast housing built in the early 1900's was built by German, Italian and Irish immigrants, but the preponderance of labor was German. Today Hans, and Adolf have been replaced by the ubiquitous Pablo and Juan. Not gettin' political here, most of the Hispanic construction labor that I've worked with are the hardest working people I've ever met, but it is a fact all the same. An unfortunate reality of that is that most of the "American" bosses don't hablais too good, especially here on the East Coast where Spanish as a second language is a somewhat newer phenomena.
Basic communication is frequently the basis for many construction oversights and omissions. I had a great framer that was the most cooperative, hard workin' son-of -a-gun I'd ever met on a crew for two days before I realized that his ever willing "O.K. boss" was the full extent of his mastery of the English language. The third day was spent renailing blocking and sill plates that he'd been told to nail off, and rechecking whatever else he'd worked on.
The realization that we used to over build everything and that the prevailing wisdoms, "concrete's cheap, just fill the hole" were unnecessary lost profits has caused the pendulum to swing sometimes a little too far in the other direction. Tighter houses use less energy but now grow mold with just the addition of an aquarium. If you're in Northern Virginia, the D.C. suburbs where so much of our tax money lives, there are tens of thousands of acres of old corn fields that have been covered in the last 30 years with giant cities of McMansions that are often two story structures covered with cardboard, tinfoil and wrapped in a thin sheet of plastic with an over lay of vinyl. There are thousands of homes in our area that have steel entry doors with big heavy deadbolt locks...that you could literally cut your way into through the living room wall with a box knife.
During the 70's and 80's many new home builders were finding out just how much they could get away with. ABS pipe, Thermax cardboard sheathing, OSB roof sheathing, stapled rather than nailed wall and roof sheathing, panelized and prefab modular housing were all gaining popularity during that time. Since then we have come to realize that much of that was a big mistake, or at least it led to a host of expensive complications for future owners, but the damage has been done nonetheless.
Do yourself a favor. If you've got the dough to afford a 100 gallon artificial reef or Amazonian river section, be prudent and invite an engineer to your next cook out. No engineer or experienced carpenter worth his salt is going to advise you with out looking at your particular situation with their own eyes. Potentially catastrophic failures are still a reality today whether your building is 100 years old and sitting on a fault line or buttressed between two pre-war brick row houses in the heart of the city. If you don't know enough find some one who does and pay them if you have to to get the peace of mind, and insurance coverage, that you probably need.
Last but not least. If you're over an unfinished crawl space and think about bracing your floor off of the dirt, don't. Go get a copy of Modern Carpentry out of the library and learn something about house construction first. Wood shrinks, dirt settles and washes away, top soil organics decompose and the soil compacts...the list goes on and on and the simpler you try to make it the more potential for a Homer Simpson moment.
Good luck.
One of the most common causes of old house floor deflection, sagging floors, is also caused by an old misconception where wider sections of wood were sometimes used in place of deeper sections of wood. That is a pair of 2X6's might be used in place of a single 2x10. Again, there is a difference, but it's not necessary to understand for the purposes of this discussion. What is necessary is that you understand that the time that this happened was between the Spanish American War and the Great War. We aren't Europe with 1,000 year old cathedrals but we have been building wood frame houses here for quite some time now.
And speaking of framing, don't take a few span tables and engineering equations and think that you're going to figure out your home's floor load designs. There are a multitude of other factors that come into play when calculating loads. Was the house balloon framed or stacked, were the joists ends given a fire cut, did the contractor get away with using a #2 or #3 grade larch rather than a #1 fir, were the doubled joists directly under the load above or offset for the plumber, did that cable guy destroy the integrity of your joists buy drilling 1 1/2" holes for his coax 'cuz that was the last sharp bit that he had on his truck that day?
As for homes built 20 years ago...well you're right on the cusp of a period when some of the shabbiest crap in America was passed off as home construction. Being in Virginia you're doubtless familiar with the fact that folks who live on the Eastern Shore of the DelMarVa Penninsula are a little different from those on the more urban western shore. Specifically here this refers to the fact that many jurisdictions over there (I'm on the western shore), didn't even adopt modern building codes until this century. Even here we have significant differences between brick shell 200 year old row houses and WW II era pallet shacks that were thrown up for the hordes of West Virginia miners that moved here to build airplanes during the war. Many of the houses along the Chesapeake are updates of updates of updates that were originally summer screen porch cottages people used to escape the city heat. Looking under these usually reveals extensive termite damage and some very creative interpretations of structural engineering and design.
Older is not better, but yet neither is modern. Most of the East coast housing built in the early 1900's was built by German, Italian and Irish immigrants, but the preponderance of labor was German. Today Hans, and Adolf have been replaced by the ubiquitous Pablo and Juan. Not gettin' political here, most of the Hispanic construction labor that I've worked with are the hardest working people I've ever met, but it is a fact all the same. An unfortunate reality of that is that most of the "American" bosses don't hablais too good, especially here on the East Coast where Spanish as a second language is a somewhat newer phenomena.
Basic communication is frequently the basis for many construction oversights and omissions. I had a great framer that was the most cooperative, hard workin' son-of -a-gun I'd ever met on a crew for two days before I realized that his ever willing "O.K. boss" was the full extent of his mastery of the English language. The third day was spent renailing blocking and sill plates that he'd been told to nail off, and rechecking whatever else he'd worked on.
The realization that we used to over build everything and that the prevailing wisdoms, "concrete's cheap, just fill the hole" were unnecessary lost profits has caused the pendulum to swing sometimes a little too far in the other direction. Tighter houses use less energy but now grow mold with just the addition of an aquarium. If you're in Northern Virginia, the D.C. suburbs where so much of our tax money lives, there are tens of thousands of acres of old corn fields that have been covered in the last 30 years with giant cities of McMansions that are often two story structures covered with cardboard, tinfoil and wrapped in a thin sheet of plastic with an over lay of vinyl. There are thousands of homes in our area that have steel entry doors with big heavy deadbolt locks...that you could literally cut your way into through the living room wall with a box knife.
During the 70's and 80's many new home builders were finding out just how much they could get away with. ABS pipe, Thermax cardboard sheathing, OSB roof sheathing, stapled rather than nailed wall and roof sheathing, panelized and prefab modular housing were all gaining popularity during that time. Since then we have come to realize that much of that was a big mistake, or at least it led to a host of expensive complications for future owners, but the damage has been done nonetheless.
Do yourself a favor. If you've got the dough to afford a 100 gallon artificial reef or Amazonian river section, be prudent and invite an engineer to your next cook out. No engineer or experienced carpenter worth his salt is going to advise you with out looking at your particular situation with their own eyes. Potentially catastrophic failures are still a reality today whether your building is 100 years old and sitting on a fault line or buttressed between two pre-war brick row houses in the heart of the city. If you don't know enough find some one who does and pay them if you have to to get the peace of mind, and insurance coverage, that you probably need.
Last but not least. If you're over an unfinished crawl space and think about bracing your floor off of the dirt, don't. Go get a copy of Modern Carpentry out of the library and learn something about house construction first. Wood shrinks, dirt settles and washes away, top soil organics decompose and the soil compacts...the list goes on and on and the simpler you try to make it the more potential for a Homer Simpson moment.
Good luck.
