TJI'S VS LUMBER JOISTS

[CREATIVE1]

I need some help here.  If you were in a damp climate (Pacific Northwest near a rain forest) with a stem wall foundation 30 inches above grade, would you be comfortable using TJI's?  My plan was engineered for them, but I've heard some negatives and don't want the joists to fail down the road.  Flooding isn't an issue, just dampness. 

[John_M]

Isn't there any way to add a vapor barrier on the ground of your foundation, to stop moisture from coming up through the ground?  I used some heavy construction plastic.

I would think that both dimensional lumber and TJI's would both have problems in the long run if there is moisture issues?

[PEG688]

20 years ago I'd have said use lumber , but today with a concrete foundation , AND proper VENTING , the "I" joist are the way to go. Even in the Forks area.

[mvk]

Peg
Do you have much experience with these, you have mentioned them to me in a different post. I like open space and have thought about them. I have no experience with them and have been out of the trade for about 15 years. My friends who are still carpenters don't like em! They are a bunch of old farts like me, set in their ways, so I don't no what to think. I'm sure there are all kinds of facts about how they are stronger then wood etc. Might be the only thing you will have to use when I get around to building if I ever do. 

If I just went 16' how do the cost out to 2x12, guess you would go 2' oc.

Mike

[PEG688]

Yes we use them all the time , they have some issues , most folks over-span them , which creates bouncy floors. They are rated for the spans , so they "really " aren't over spanned , BUT  no one likes  a bouncy floor.

Lumber as you know is pretty crappy these days so IF IT where my cabin , or one I was building ( contracted to build / IF I where the business owner)  I'd do one of two things.

I'd go hand select my own joist , sounds like your building a 16' wide place , is that right?


If so ,

#1: I'd go select / hand pick the 2 x12 DF joist. MYSELF. As well as the rim joist stock and the beams. 

#2:  If I could not go hand pick the joist , I'd use TJI's or BCI's and I'd go with a joist that was span rated for at least 20' , whether that meant  using a 11 7/8" joist as opposed to a 9 1/4"  , I'd go to bigger  joist in size and I'd stay at 16"OC IF I where using 3/4" T&G ply.

If you want to go to a 24" OC span I would recommend a 1 1/8" T&G ply product, even at a 19.2" OC  spacing it is my opinion that 3/4"T&G flex's to much between the joist.



G/L PEG

Edited for clarity , I hope     

And yes it would be stout as it is something I do know about .( See tag line for clarity/ joke / pun) 

   

     

[Jackson Landers]

Think about how long it takes for an open flame to burn through a 2x joist. Something like 25 minutes. Then think about how long it takes for the same open flame to burn through the thin webbing of an engineered I joist.  What, like 8 minutes or so?

Sure, engineered joists are every bit as strong as a regular joist. Stronger, really. But in the event of a fire, your house will experience structural failure and collapse under you or the firefighters who ran in to look for you much sooner.  A very hot, serious fire can burn downstairs for as long as 5 minutes before someone in a bedroom with a closed door upstairs smells it. With engineered joists, that doesn't leave you or a family member with much time to find a way out of the building before the floor collapses under that person and he or she falls into a burning pit of hell.

Don't do it. Don't use engineered joists in residential construction. Garages, outbuildings, recreational buildings, fine. But please don't use these things any place where they will be underneath sleeping people. If you don't believe me, ask an experienced firefighter what he thinks. My family has lost people in a house fire and I can tell you that you DO NOT want to take a risk like that for the sake of a more open floor plan.

[John Raabe]

PEG's solution is VERY sturdy!

But deflection (bounce) is at least partially subjective. The span charts I use in my plans for I-joists use the 1/480 (improved performance) tables that are more than the code required 1/360 deflection. This (improved performance) standard is satisfactory to most people. However, having your 300 pound brother in law doing jumping jacks in the living room will jiggle the china cabinet a bit!  . If you don't want that follow PEG's suggestion (basically going up one joist size from the 1/480 chart).

I think PEG means to say to go to an 1 1/8" subfloor if you go to 24" centers for the joists.

[PEG688]

Think about how long it takes for an open flame to burn through a 2x joist. Something like 25 minutes. Then think about how long it takes for the same open flame to burn through the thin webbing of an engineered I joist.  What, like 8 minutes or so?

Sure, engineered joists are every bit as strong as a regular joist. Stronger, really. But in the event of a fire, your house will experience structural failure and collapse under you or the firefighters who ran in to look for you much sooner.  A very hot, serious fire can burn downstairs for as long as 5 minutes before someone in a bedroom with a closed door upstairs smells it. With engineered joists, that doesn't leave you or a family member with much time to find a way out of the building before the floor collapses under that person and he or she falls into a burning pit of hell.

Don't do it. Don't use engineered joists in residential construction. Garages, outbuildings, recreational buildings, fine. But please don't use these things any place where they will be underneath sleeping people. If you don't believe me, ask an experienced firefighter what he thinks. My family has lost people in a house fire and I can tell you that you DO NOT want to take a risk like that for the sake of a more open floor plan.

I asked this question to a professional F/F buddy of mine ( yes we have met each other at wooden boat shows so he is areal person).

My question :
  Quote:
From a Fire Fighters prospective, IE faster burn thru / potential collapse on rescue?

Is that a factor in your attack plan? 


His answer :

This only touches on one perspective of lightweight construction. Yes, they burn through faster than older types of 'solid wood' construction, but they typically don't fail as fast as lightweight trusses. By not as fast, we are only talking minutes of time. Typical rule of thumb is that if a lightweight component is exposed to flame, you have a bout 10-15 minutes before failure. factor in the time for somebody to call dispatch, dispatch to call us, turn out time and response time, we usually arrive right at collapse time.

Lightweight trusses fail sooner due to the gangnail plates used to assemble them. These metal plates absorb more heat and transfer it more readily into the wood via the little spikes on them. This heat transfer causes faster pyrolysis and degradation of the wood that holds the gangnails in place. On a truss, all it takes is one component to fail with catastrophic results. I had and addition to my garage added in my last house. The 24' span trusses were 2x3! Yes, 2x3 not 2x4!

Engineered joists don't have that metal component, so to fail, they need to burn through and also have the floor decking above fail in order for collapse. I have been amazed to see the amount of extreme burn through on this joists (After a fire) and th floor above was still able to support weight.

This is a very involved topic that we debate in the fire service. What is the best tactic, ventilation and time frame? Add to this, the 'new' houses that look like an older stick framed house and there is another variable we have to consider. Oder houses (stick framed) were typically made of larger components and mass is what gave us the time factor before collapse. We were working a fire several years ago and my guys were getting very concerned about the time that the house was involved, and they were fearing collapse. As I pointed out, the house was built in the 50's and would withstand a greater amount of fire before w would have to worry. We worked that house for well over and hour and never had a problem.

I guess in my Department we have been fortunate. We haven't had a collapse to my knowledge since I have been there in the past 17 years.

I realize that we can not build all structures with firefighter safety in mind and that lightweight components are going to become more and more common. It is a matter of being aware of your surrounding, not getting overly confident and what I would like to see it better fire protection of those lightweight components. A 1 hour separation with sheetrock may last that long in the laboratory, but if it makes it 20 minutes in the real world it is amazing.

Am I getting close to the answers you are after?



So long term I don't know what it's worth , I guess each person should decide for themselves. 
 

[CREATIVE1]

Isn't there any way to add a vapor barrier on the ground of your foundation, to stop moisture from coming up through the ground?  I used some heavy construction plastic.

I would think that both dimensional lumber and TJI's would both have problems in the long run if there is moisture issues?

We have to build to IBC2006, so there is a vapor barrier on the ground.  I raised the foundation  up a tad to allow more room for air circulation (?don't know if it helps, but it also gave us more room to access plumbing). I'm concerned about using something made of OSB, Strandboard, or whatever you call it because our ten year old well-constructed and painted shed on the property made of such stuff is showing some swelling and damage.  I'm using plywood everywhere because of that too.

In winter it is super damp and cold enough so that nothing that gets wet can dry.  Our house is well away from the trees, so we are doing OK there.  Despite the extra expense, we're going with metal because shingle roofs get mossy and start breaking down.You would be amazed at the damage to construction less than 40 years old.

[CREATIVE1]

Lumber as you know is pretty crappy these days so IF IT where my cabin , or one I was building ( contracted to build / IF I where the business owner)  I'd do one of two things.

I'd go hand select my own joist , sounds like your building a 16' wide place , is that right?

Yes, 16 foot wide Victoria.  Great suggestions, but a shame that lumber is so crappy you have to go through extra trouble.



ED: repaired quote/message for better readability - MD

[CREATIVE1]

Think about how long it takes for an open flame to burn through a 2x joist. Something like 25 minutes. Then think about how long it takes for the same open flame to burn through the thin webbing of an engineered I joist.  What, like 8 minutes or so?

Sure, engineered joists are every bit as strong as a regular joist. Stronger, really. But in the event of a fire, your house will experience structural failure and collapse under you or the firefighters who ran in to look for you much sooner.  A very hot, serious fire can burn downstairs for as long as 5 minutes before someone in a bedroom with a closed door upstairs smells it. With engineered joists, that doesn't leave you or a family member with much time to find a way out of the building before the floor collapses under that person and he or she falls into a burning pit of hell.

Don't do it. Don't use engineered joists in residential construction. Garages, outbuildings, recreational buildings, fine. But please don't use these things any place where they will be underneath sleeping people. If you don't believe me, ask an experienced firefighter what he thinks. My family has lost people in a house fire and I can tell you that you DO NOT want to take a risk like that for the sake of a more open floor plan.

This is a real eye-opener.

[MountainDon]

That is food for thought. But so is the information from Paul's fire fighter friend. Note that he said in his experience the 2x and gang-nail metal plate trusses are the worst. The I-beam type do seem to be better.

FWIW, more food for thought...

Fire Info on TJI's (a PDF file)

and another with more info

[JRR]

A few months ago my wife and I decided we would drive around the country ... starting out from Georgia.  We drove more or less in a straight path to Seattle, did a clockwise loop up thru British Columbia ... back down around to Portland, down the coast to San Fransisco, and finally turned back to the east hugging Mexico, the Gulf, and then back up to Atlanta.  Over 5 weeks, over 9500 miles.

It was our first time to see Oregon and Washington State in such detail.  Wow!  That coast, all the way down, was just mind boggling for this old Southern lad.  The water falls, the rain forest ... really beautiful.  But I see the problem with moisture.  (Are there ever any brush fires there?)  I think it rained on us every day.

I wouldn't know what to suggest other than what PEG and John offer.  They live in that neck of the woods.  But I'm reminded of a well-house I once built.  It was built using  concrete block around the drilled well.  12x12, two storied.  In the damp forest near the house. The upper floor was to be a summer playhouse for the kids.  The lower space not only had the well-top, there was the water storage tank and the jet pump.  I expected dampness ... and got it!  Everything on the first (earth) floor was usually moist to the touch as the cool water brought up from the well would cause much cooling and sweating.

Instead of wood joists, I used homemade reinforced concrete beams for the second floor.  Took a bit of work, they were poured in-place.  They extended beyond the wall for a counterlevered porch. The second floor was like an upside-down flat roof:  T&G 2x's with roof felt plastered underneath.  The real gable roof had wooden rafters, t&g decking, and spanish tile on top.  The upper story stayed nice and dry but the first floor was always wet and dripping in warm weather.  Any steel or iron pipes or equipment was not gonna last long in there.  Angle iron, supporting the pump, just melted away over the years.  All doors and windows stood open except for dead of winter.  But the concrete beam/joists did their job, they are still there.

[CREATIVE1]

There was a fire near Mount Rose two summers ago that smoldered for awhile because it was burning in rough country and couldn't easily be reached.  The summers are dry-ish.  We're on the wet side of the mountain, and in a place essentially without lightning.

Any environment poses special problems that have to be addressed in style and materials and site selection.  That's also why our property is cleared 100 x 150 feet around the house--lack of sunlight and the dampness problem.  I'm glad someone else cut the trees before we purchased it.

My son would love your solution with concrete.  He seems to like it as much as I like wood!  And for your viewing pleasure, here's our lake.  We live to the right and bottom, on Dow Mountain.




ED: repaired img tag so image would show here - MD

[JRR]

...!!!!  That is fantastic!

[MountainDon]

Looks like a great place!  Little wetter than my desert here.   

[CREATIVE1]

Looks like a great place!  Little wetter than my desert here.   

Just a tad!  If you stood still too long, you might turn into a fungus among us.

[John Raabe]

Yep, pick your poison...

In the desert the wood dries and cracks up and you have to check your shoes for scorpions.

In the Pacific NW the wood grows mildew and rots and you have to check your shoes for slugs.