hey all,
I’m probably the last guy on earth who hasn’t used engineered floor joists.
Can anyone give me the pros and cons of these modern wonders?
I’ll appreciate any info that’s more informative than a sales brochure.
Thanks kmac
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They're long, light, straight and strong. The major caveat is they'll fail faster in a fire then conventional lumber. I've used them in my place and I'll use them again, I just add more fire protection in areas around a garage or kitchen.
On previous threads about them, some of the guys thought that they wouldn't hold up as long (time wise), or be as stable in say 25 years. A lot of that has to do with, I think (and correct me if I'm wrong), the idea of a lot of the new engineered materials (OSB, mainly), that some have had a lot of trouble with. That, coupled with the idea that regular floor joists have been in use so long has not helped their reputation among some of the finer builders who post here.
That being said, I would not use ANYTHING but engineered floor joists, even on very small additions. They are light, fast, strong, and basically perfect. They save me a lot of time on installation, and make a much better floor system IMHO. I say this because we cannot get any type of decent lumber here. We have nothing but SPF #2 available, and quite frankly, it's horrid; huge crowns, knots you can see thru (and sometimes stick a finger through), strange and unusual dimensions (the heights vary up to about 1/2" among the same bunk), plus the usual splits and cracks. It takes us less time to install these than it did culling the crap we got. And they basically make perfect floors. Just my 1.02 there...but for our area and operation, they're the cats' ass.
I've used enginered floor joist in more than a hundred homes and find that they are the product of choice to most builders. However they definently have there good and bad points. The good being that there light,strong,straight,and almost any lenght that you need. They seem to hold nails better than dimensional and make a much more sound floor. The cons are that it is made of osb and laminated wood. The problem with this is that nailing to close to the end creates splits which can undermine the fact that they are enginered. Also definetly glue down your subfloor to prevent squeks from missed nails or nails that just catch the edge. Another problem is that in areas where a water leak may occur the joist could potentially fail over years of water damage. Not saying dimensional would not fail or rot just that It would take longer and can handle more abuse. As mentioned above they are very flammable. In subfloors it is not a real concern, however for ceiling and garage areas two layers of 5/8 drywall is necessary. I would however use them myself.
We have used engineered "I" joists for the last 4 years or so and I have to agree with whats been said above. One other pro I will add is that these joists are much more dimensionally stable after going through the first heating season of the home. With the dimensional lumber available in our area, this has always been a problem. Callbacks after that first winter to re-adjust doors out of whack from floor shrinkage and moving joists is eliminated for us. On a basic plan they will save labor also, but in a complex layout there is a little extra work with proper details. Another pro is the availability of the 14-16" high joists capable of clearspaning garages for bonus room space. Overall I do prefer them.
Fire protection is a definite concern and recently hit close to home. In this case it involved an open web floor truss system rather than "I" joist, but I think the concerns are similar. I am a fire commisioner in our rural town, and last year we hired as a part time paramedic/firefighter a young man who died a couple of months ago, along with one of his fellow firefighters, in a structure fire. The house was about 12 years old in a neighboring town. The fire fighters arrived at the scene, with no visible fire apparent but a lot of smoke. It seems the fire was in a basement workshop area, hidden from view. Upon entering the building the two firefighters were unknowing to them, directly over that area of the basement, when the floor collapsed under them, sending them directly into the inferno. The rush of Oxygen caused the fire to backdraft over the top of them, hampering rescue. It took hours to recover the bodies. It seems the metal plate fasteners failed on the floor trusses causing total failure.
We are currently talking of possibly notifying 911 on all new construction of the prescence of both roof and floor trusses, and considering local surveys of existing homes for these trusses. 911 has the capability to notify responding depatments of this type info. Possible code changes may also happen in our area due to this incident. We also are looking to better educate firemen on the types of construction being used now. You can never completely eliminate the risks in this type of incident but hopefully some good will come from this.
Bish
I choose to use timbers for my home. Their size ensures durability, their cost is much lower than engineered products yet will in time give the floor some lovely character which cannnot be achieved with engineered product.
Walk thru the finest homes in the area and drop a marble on anything hard. True level floors the marble wouldn't roll. I have yet to find a house that the marble won't roll, if not this year, in a couple of years when the settleing is done.
Once you accept the fact that no floor will ever be perfect,why not enjoy character? Squeaks? they can be dealt with, nail pops? well, use ring shank or screw.
To me there is a durability question when you glue something together, moisture is a fact of life, moisture cycles could damage a engineered product faster than timbers.
The next step from engineered products is plastic products, are you prepared for that?
I only use them for ceiling joist in garages with rooms above so I will not have to use support post. If you are doing your own framing there may be some labor savings otherwise dimensional lumber is less expensive (and in my opinion better)
I like LVL's but do not care that much for I-Joist. If you use the mfgs table and use the code acceptable your floor will have quiet a bit of deflection. Until there is a real cost savings I cannot see using them
I am currently building a home for my family. I am using ICF's for walls which may be considered cutting edge. However, for the floor I will be using 2x8, 2x10, 2x12 all 12" o.c. for the different spans.
Danny
sparkies like 'em, justb hit that ko wHammer, no drillingno turn left unstoned
Bish -
A couple of points I would like to contend on your post -
First, Wood webbed Floor trusses don't necesarilly fail more quickly in a fire. Depends on the fire, building construction, and other circumstances. But let's say for the sake of arguement that they do fail more quickly. If the fire fighters had arrived a few minutes later, and the house had 2X10 floor joists, they might have also been at the point of failure. The added weight of the fire fighters could have also made them fail. (Like it apparently did with the floor trusses)
Or the floor trusses might theoretically failed before they got there, so they could see that the floor had already colapsed and subsequently not gone in. Sound like a tradgedy based more on bad luck and bad timing. (Not to minimize the loss of life here)
I don't agree with the notification of emergency services thing regarding roof and floor trusses and/or I-joists. What I would prefer to see is that firefighters don't enter burning buildings unless there is someone inside that needs rescued. There's no sense in risking people's lives to save parts of buildings.
Also - The metal plates don't fail in fires. The wood burns away from them, and so they become ineffective becuse they have no wood to grip anymore.
There's more info here, if you care to read it:
http://www.woodtruss.com/fire.htm
Edited 5/20/2002 7:31:39 AM ET by Boss Hog
This is sort of unrelated, but.......
Take a look at the following link. (Loads an adobe acrobat doc)
http://www.woodtruss.com/images/firedeathcause.pdf
According to that, 45% of fire fighter deaths are caused by heart attacks. That seems amazingly high. Anybody in the fire service that can comment on that? Is it accurate?
I always wanted to be a procrastinator
Boss,
I'm a firefighter/paramedic and yes, about 1/2 of the firefighters that die in the line of duty die of heart attacks. Not surprising if you consider that we wear about 40-65 lbs. of gear and go into buildings that are HOT, temp. can reach 1200F just prior to flashover and when you put water on the hot stuff you generate alot of steam. It is very stressful on your body. Imagine doing hard physical labor in a snowmobile suit in the summer.
In the previous discussion about truss joist and trusses in general, in a fire condition these will fail much sooner than solid wood joist. The gusset plates that hold roof trusses can fail in 10-15min of intense heat. I-joists also burn through very quickly, just put a 2x12 and a truss joist in your burn pile and watch which one is gone first. Solid wood tends to seal itself once charred and wont burn as fast and that coupled with the fact that when solid wood is burned through at about 50% it still has a high percentage of its original structural integrety.
Having said that, we're build a new house this summer and we'll probably use TJI's, microlams and maybe tusses...have to work on the budget alittle more and see.
Will these houses last 150yrs. or more.. I dont know???????? I wont be around to find out.
Lt. Brian Green
http://www.wlfpd.org
Brian -
Glad to hear from you. I wasn't surprised that firefighters died of heart attacks, just that it was such a high percentage. Is this something that the fire service is addressing? I've never heard it discused before.
As for "throwing things on a burn pile" - That hardly represents actual fire conditions.
I'm not clear why you said "when solid wood is burned through at about 50% it still has a high percentage of its original structural integrety.
" I'm not sure that's true. Charred wood is basically assumed to have zero strength.
I'm curious what you think about my suggestion of *NOT* going into buildings if no one is in them. Haven't heard this discussed much in the past.......
Grammar has gots to be one of the most importantest things ever
50% of the cross sectional area still unburned. Will not be as stiff, but still retains a remarkable percentage of it's original strength.
Edited 5/20/2002 1:37:48 PM ET by Uncle Dunc
I think TJIs are a definite plus in construction. Uniformity of product, no warping, checking, wane, cracks, splits, knots...
The web is not run-of-the mill OSB. It used to be, but several years ago the I-joist manufacturers took over control of the manufacturing of the web material. they manufacture it to higher tolerances than standard OSB sheeting, and thus get a better product.
I'll use TJIs in every floor.
Fire? They definitely burn faster than 2-by joist lumber. I use 5/8ths fireboard for ceiling gypsum board to cover the bottoms of the TJIs. I also use 5/8ths on the inside of the exterior walls. It may not help much, but whay not?
I used TJIs in my house, and I'll sleep well if my kids use TJIs in their houses, too. I also used all 12ga wire in my house, didn't back-stab the outlets, didn't overload the boxes, or overload the circuits. Good smokes, both versions.
A little bit here, a little bit there.
I don't use TJIs as roof rafters unless required for span, and then that's usually in a cathedral ceiling. I never truss, I always stick build roofs.
" I never truss, I always stick build roofs"
You sure know how to hurt a guy, don't you ???...........(-:
My identity lies in not knowing who I am
Boss,
If I had a quality man like you to design my roofs, perhaps I could be persuaded...<g>
Just tried the following center blocking method on a 17' + TJI span:
5/8" plywood gusset each side of TJI @ centerline, full height x 16" long, glued and nailed
2 x 4 blocking (vertical 2 x 4) from gusset to gusset
3/4" sturdifloor T & G subfloor, screwed & glued
I'm VERY impressed with how solid and stiff this feels compared to other center blocking methods, like TJI cutoffs offset. If you really want to go nuts you could shore the joists slightly first.
T. Jeffery Clarke
Quidvis Recte Factum Quamvis Humile Praeclarum
Edited 5/21/2002 9:30:17 AM ET by Jeff Clarke
Boss,
I think uncle D answered the cross sectional area question when joists are burned through. I put an ax (checking structural integrety of the floor) through some tongue and groove flooring that had burned through and completed my search in a fire 2 wks ago--later we examined the joist and the floor. If you scraped away the charred joist you had about a 1"x10" (2x12joist) of intact wood left, and that held up the bedroom furniture and 220lb of me.
The NFPA generally controls alot of what the fire service does, and it has been recognized that a good PT program can help lessen the # of heartattacks, but I'm also not sure of a manditory standard other that yearly physicals. Alot a firemen that I know also smoke.
As far as fighting a fire from outside---Old school guy scoff at that and use the #### word alot. We have a saying in the fire service that probably applies to alot of things in life; RISK VS. BENEFIT. We do interior attacks and primary searches because maybe the vacant build was occupied by transients, maybe the family that was supposed to be on vacation came home early.....now having said that if the fire is too large and a risks are too great ( and the people were certainly crispycritters) we would fight the fire defensively (from outside)....in fact we often initiate and attack from outside. Sometimes putting out the fire is the best way to save someone. We take risk, but those risks are calculated. I have a family to go home to and so does my guys, that is the ultimate goal...everyone goes home safely.
Hope your quote doesn't reflect on my grammer.
BG
FWIW I stumbled on this these fire test done by U of Cal Forest Products Labs.
They are all on outside of home, decks, walls, roofs, and windows.
http://www.ucfpl.ucop.edu/WDFireResearch.htm
On the deck test they they test many composites and some wood.
A few of them did not last but a couple of minutes from a fire below.
Boss,
I will agree with you that with some changes in the circumstances that night, out come could have changed. In this case, it certainly does appear that the trusses failed, wether from actual plate failure, or failure indirectly caused by the wood burning away from the plates causing them to loose their grip. I still use trusses and I joists and believe they are here to stay.
As Brian states here, heart attacks happen so often because of the combination of heat, physical exertion, mental exertion, etc. Our local dept., which I've been a member of for over 25 years, now requires mandatory physicals every year for active firefighters. Our ambulance and medics roll at evey fire call possible, and the medics monitor everyone working the scene.
Also stated here, there are many times the fire has to be attacked from the inside. The fire command has to acess the conditions and determine if the attack can be made safely. You don't always know if a place is unoccupied. In this case, these firefighters were paid, well trained, experienced men, who unfortunatly entered a building that had hidden fire and died because of it. I am not saying that we shouldn't use the material anymore, but believe that there does need to be better awareness of new materials for these firefighters. Right after this incident, there was much talk by local lawmakers of new laws to either outlaw these joists or require stickers on the front of any homes using them. I disagree with both of these. I know when I build someone a $3-400,000 house, they wont be to pleased to have a bright orange truss sticker in front and it probably wouldn't last 6 months before dissapearing.
Bish PS. Interesting link you posted.
three points here,
First there is hundreds/thousands of years of experiance with timbers/ solid wood joists. We know how durable they are and how well they survive a fire or water damage. The durability of TGI's have yet to be proven. who knows if they will become another failure like asbestose insulation. At one time it was the best thing because of it's fire resistance.
Second is cost.
Not just the up front cost of making them, that require large expensive factories but also the energy cost they require in their fabrication energy which is viruatally non-replaceable. In addition large central factories have monster distribution costs, both on material required to run them and on storing & distributing.
Third
the cost to society. OSB is frequently made with fast growing wood like Aspen. Hundreds and hundreds of acres of aspen. grown like corn for maximum growth/ minimum harvest cost. Hardly the dream of picnics and hunters. The forest and woodlots serve multi purpose. When that purpose is denied society is denied.
Finally someone commented that he wouldn't be here in 150 years so why should he care.
I hope that was simply light hearted attempt at humor. In the event others take it seriously , please rethink. If it takes more than your lifetime to grow the material to replace that home then you should care. While there are a lot of trees in the forest, the number is limited. There are no longer any old growth forests available for harvesting. Thus the wood of today is vastly inferior to the wood of yeasterday. Think of the wood that was wasted in the past because of poor management. It's too late for that, now if we continue to build disposable homes we'll run out of our wood sources.
There are still virgin forests in the former Soviet Union, is that what we have to look forward to? Importing Russian wood?
While I agree, Frenchy, that there's a long history of solid wood products, I have to disagree that we really get the same product anymore. The larger dimensional lumber I see is basically unfit for any type of home, let alone a home of any type of quality. Secondly, I guess I'd also think that it's fire, water, and mold resistance ain't nothing like it used to be. So sure, solid wood USED to be great, but it ain't anymore. Also, lumber here and in many places is like any other crop...it's grown for use just like corn or potatoes. I'd much rather see it treated as such, rather than more of the truly older forests taken out simply for better quality floor joists. Will TJIs and other engineered products stand the test of time? I'd guess so...remember, it was only a few short years ago that "plywood" was the bastard cousin of "real wood" for sheathing...but then again, only time will tell.
Jason,
you make several good points and I have to admit that my perspective is slightly skewed. I'm building my timber frame out of mostly old growth timbers that were too difficult to access during the hayday of logging in this region. The quality of my wood is great and I honestly don't look at the few boards I've purchased at the local "yard" I need some tonight so I'll make a point of it.
As for the test of time, plywood only has to last another 400 to 500 years before some of us tradionalists start to accept it as a serious building material. As for me, I'm not certain that I'll wander around the suburbs of the future staring in awe at those 4x8 foot sheets of 3/4 inch plywood the way I do at the timber that holds up those old homes and churches of Europe.
Yep....it's all in perspective, Frenchy my friend. My own timberframe/SIP home is built out of much newer growth spruce. I've learned to work (and caulk, and paint, and trim), around it's ever changing dimensions. On the other hand, I got to contract a 4200 square foot log home a couple years ago, with 38" old growth pine, from one of the last stands of such wood in my state....almost a shame. It's always a hard choice (or should be), to make the right decisions in design, engineering, style, and in this thread, materials for any project. I shudder to think of the legions of 1950's post-WWII "housing" that used old growth, and what we could do with it today. On the other hand, I also think there's a place for using certain types of wood, particularly if it makes the structure last longer through either longevity or through design. But then again, and as I said...we don't get wood like that. I'll continue using TJI's and other engineered lumber, both because I think it's the wave of the future, and because it makes the most design and construction sense for the type of construction we do.
Movement in timberframes isn't only among 2nd/3rd growth wood. I was working on some of the timbers inside this winter and If I measured things shortly after bringing them in, the timbers were as much as 1 3/4 inch differant than once they'd been in for 24 hours and warmed up.
That was on old growth (some as much as 300 years old) white oak. It caused some real problems while I'd sit there trying to get those timbers to stop wiggleing and dancing. I made templates and would cut timbers to fit the template and come back in the moring and find giant gaps. I'd grumble and reject the timber only to have the same thing happen again and again. After I looked over and noticed that all 4 rejected bents were exactly the same length, the light bulb went on and then with just a little tune-up made everything fit again.
Please don't mis-quote me, my original statement was:
"Will these houses last 150yrs. or more.. I dont know???????? I wont be around to find out."
Not that I don't care....I certainly hope that a home that I build will last for more than just a decade or so.
BG
It is interesting, Frenchy, that you criticise engineered products as being inefficient uses of wood or energy because those are the things that are most often pointed out as their benefits:
Engineered wood is supposed to make use of inferior woods to create structurally similar products to dimensional wood. As you pointed out, we don't have much more old growth wood to rely on any more so hopefuly the engineered stuff will work in its place.
The other interesting thing that you said is that the forrests grown to produce eng'd wood can't be used for picnicing and camping because they lack diversity. Well does that mean that we should stop farming in the midwest then? That whole prairie was converted from a diverse ecosystem into a food producing region. The huge agri-business has been unbelieveably efficient at producing all the food for our needs and for a lot of the rest of the world as well, the cost savings is so large, in fact, that the transportation costs shrink in comparison. Much the same will probably be true of the eng'd lumber business, transportation costs continue to drop historically and centralizing production has continued to be more efficient in many industries.
Now, these trends could change, or reverse, but as long as they exist we'll likely see business move towards them.
The costs to our society of any big change are always a risk, but sometimes the change is too big to prevent/avoid. The best thing in these cases is to find the most good and to find ways to avoid/minimize the bad in them.
For instance, if some fast growing Aspen 'farms' can provide the wood material for a factory that will allow some other forrest to return to an 'old growth' state over time, or allow us to protect the remaining old growth areas with more ease, then that good could outweigh that bad.
I can't speak with authority about other regions, but in the Pacific Northwest, there is a misconception about the lack of diversity in tree farms. While I watched with dismay the rambunctious old growth Doug Fir harvests during the 70's ( and often the export of same), the young tree farms are actually quite diverse. In the clear cuts and new plantations, browse for elk and deer and most other wildlife habitat is abundant and many bird and mammal populations increase because of those new environments. It's not truly a monoculture as is often believed.
Having said that, there are plant and animal species that are dependent on more mature forests and fortunately, the timber industry (which I was part of for many years) had to scale back it's appetite. There are some large tracts now protected, of course, hopefully, enough to ensure the survival of some of the more obscure, albeit important lifeforms. (Do you ever wonder why we put most of our effort into rescuing those critters at the TOP of the food chain?)
A current reality is that if suddenly the timber industry was given access to remaining old growth, there are few mills left with the capacity to handle it, not to mention the heavy logging iron required to harvest it. Some people would bitch even if they were hung with a new rope.
What happened to those old mills? are they still there just not or under utilized? OK there aren't too many trees that you can drive thru any more, but I still see trees that are much larger than evan the largest sawmill around here can handle.
To my knowledge the mill near La Cresent which has a 60 inch bottom blade and a 42 inch top blade is the largest in Minnesota. Thus if you need to through and through a log the biggest they can do at present is around 35 inches across. larger than that they need to slci it apart piece at a time.
I remember seeing some blades that were pretty big. have they all disappeared?
There are a few scattered old growth Doug fir mills in Washington and Oregon and Northern California, but most operators have converted to "small stem" (a lovely term!) technologies simply because there isn't an available and reliable source of big timber to support the appetite of those mills. I worked in Maintenance and Engineering in several of those mills (all but one are now parking lots and one of the parking lots is for an Indian Casino) and a couple of them were capable of, and did, cut over a million board feet of lumber in a single day! (two shifts).
There is old growth timber left, but most of it is on public land. The big players harvested most all of the original timber from their own lands, finishing up that task in the 70's and 80's because, in many cases they could make a $killing on exports of logs which they were not allowed to do with public timber.
While that was being done, they were researching alternative methods of wood fiber utilization, and have brought us to OSB, TGI's, Micro lams, Para lams, etc.
I, too, do some timber framing and log work and I really love to work with the old, tight grained wood, but modern west coast tree farms are pretty much on 50-year rotations at best (it's all economics) so in the building industry, we're pretty much at the mercy of engineers, glue, and special instructions.
When I come across some of the old, big wood to use in a project, I feel priviledged.
Out of couriosity, how large did the larger blades get? I've been in some national parks out west and looked in awe at those giant redwoods and wondered what diameter blade was used to turn those into siding?
Can you give me directions to some of the remaining mills that still are set up for large diameter trees?
Edited 5/25/2002 8:24:37 AM ET by frenchy
The mills I worked in and am familiar with were/are bandmills. The bigger ones run wheels 10 feet in Diameter. The bandsaw blades are often about 11" wide when new and some headrigs were double cuts which means there were teeth on both bandsaw edges and would cut both directions as the log passed the saw on the carriage.
Probably the most fascinating mill is Hull-Oakes Lumber Company south of Corvallis, Oregon. (I believe it's still operating). It runs entirely on steam off overhead pulleys. What's most unique about it is that it has a very long carriage rail on the headrig and a trailer can be attatched to the carriage to enable it to cut very long special order pieces. Several years ago, Hull-Oakes got some publicity for cutting some 110' long x 6" x 6" clear fir beams to replace the bulwark rails on the USS Constitution.
Email me [email protected] and I'll get an updated listing of active old-growth mills together for you.
Oh, to answer your redwood question...I'm not on real firm ground there since I've only driven through that area from time to time. I do know that some of those mills also use big bandmills but with longer centers between the wheels to allow for longer distance between the sawguides. And I've also seen some redwood butt logs split and quartered. Not only is redwood BIG but the butt logs (nearest the stump) are notoriously heavy because they contain a LOT of moisture, so handling is a consideration, too.
Edited 5/25/2002 9:31:18 AM ET by Notchman
Valid point,
I think I pointed out that not every parcell of ground needs to be "saved" nor should we be overly concerned about what an individual does with his own woodlot. I mean I would hate to be told what I can and cannot do on my own land. I should expect that forest products companies are the same.
Yet total loss of wild forests has it's own costs as well.