Hi all
I saw this the other day on site.
The upstairs floor joists are made of 6mm masonite with top and bottom cord made of laminated 70x30mm pine. :eek:
I just had to take a piccy to share with yous lot.
Al
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Hi all
I saw this the other day on site.
The upstairs floor joists are made of 6mm masonite with top and bottom cord made of laminated 70x30mm pine. :eek:
I just had to take a piccy to share with yous lot.
Al
****!!
That looks actively dangerous. The top and bottom chords on the RH joist in the photo are already splitting.
Is it legal?
Must be, the builder I am working for, beleive it or not ARE quality builders.
It just shocked me to see masonite used in this way.
Al :)
Shouldn't there be a double top plate? :confused:
Strewth!
I've seen some dodgy jobs before, but that one's right up (down?) there...
Has the owner seen this "clustermuck"?
Cheers!
Tell me it's a trick photo!
Or get me the web address of the company that do the joists!! My understanding of hardboard (masonite) is that it may just sag a bit when it gets damp, when it sags it may just cause the flange to fail??
Teejay?? or any other engineer????
Help!
P
:eek: :confused: :eek:
There are only double top plate on the outer walls.Quote:
Originally Posted by DavidG
Strewth Im a brickie and even I know that. :rolleyes: :p
Al :D
Sorry Midge.Quote:
Originally Posted by bitingmidge
The piccy I took, is what I took, no trickery.
I too think that with moisture, even if the web is water proofed, must sag/bend over time.
Al :eek:
Here is another one.
Al
They are very similar the the hyne beam which uses plywood instead if masonite. It is much stronger than you think. They can span further than regular joists. are much lighter and can be drilled thru in case plumbing or electrical cables are needed. I have never used those masonite types but all floor trusses are engineer designed. The strength lies in the glue and the way the thickness of the material used, not in the pine plates. Most times its just mgp10.
Try and bend a piece of masonite along its narrow end. Virtually impossible. You`d be amazed what is being used in construction.
That splitting is probable caused by the nails that are driven in to secure it to the top-plate.
stef
Thats it Smart Frame.
I tryed to search it on Google, but got nothing.
Al :(
Crikey, I've heard about them, now there they are, look worse than they sounded..............hmm wonder how they react to deflection or torsional pressure, moving clay soils all that sorta stuff.
If using this crap can save one more tree for me, Im all for them.
Al :D
They are engineer designed.
So was
The Titanic
& The Space Shuttle
Now Al I know you're tongue in cheek, cause masonite is made from what?Quote:
Originally Posted by ozwinner
not commenting on the pale crap either side of it tho.
I dont think Id like them in my place.
I used 250x50 Irish pine for my exposed ceiling with a tiled roof at 450mm spacings.
How would these things stack up to that?
How would you like them as an exposed feature? :eek:
Al :)
Sweepings off the floor?Quote:
Originally Posted by E. maculata
Al :D
Mmmm, i believe Hardwood fibres might be present in that there masonite, no glue just shredded hwd liquified, stirred and pressed into board using heat & pressure.
My understanding anyhow :cool:
You got that right! :eek:Quote:
Originally Posted by sol381
I'm sure you intended this comment to be reassuring. Why don't I feel reassured? :(Quote:
Originally Posted by sol381
Well see what happens when a bloke goes to sleep for a bit! The world just keeps getting smarter.Quote:
Originally Posted by
Ply and chipboard I've seen, but now hardboard too!
Why do I suddenly long for the good old days?
P
:eek: :D
Just wait for the cardboard to come on line...Quote:
Originally Posted by bitingmidge
Al :D
Guys, this is a standard construction technique nowdays. All our neighbours have sold out and subdivided and without exemption all the McMansions going up use this technique for the upper storey.
I have a suspicion that these joists are probably as strong as the traditional. They don't seem to mind getting wet either, as it has rained lately and there's been no attempt to keep the water off. They cant all be shonky builders, can they?
Even though I do work on the McMansions, I cant see them outliving 30 years.
Maybe thats the thing, built in obsolesence.
" Im sorry Sir, but you house has reached its use by date"
"please select from the following new houses ( at your expense of course ).
Al :)
Built-in obsolescence? Is that what they call shoddy workmanship nowadays?
I managed to take the trend towards laminating treated pine for bearers and joists in my stride, I can even turn a blind eye to the use of sheet ply and a nailgun in lieu of lintels over doors'n'windows... but the latest has me stunned. For a few years a polystyrene cladding has been used in lieu of blueboard for external upper stories, with good reason; but to use lightly rendered polystyrene as the sole cladding on the groundfloor? :eek:
Can you imagine? Your kid flies up the driveway on his bike, comes to a screaming halt throwing the bike up against the wall before belting inside to throw himself on the couch.
Only to find that he can't, 'cos the bike fell through the wall and beat him to it. :D
Seriously, at the latest site I'm working on, a new house of dubious quality sited on high-value beachfront (suitably priced for the rich but stupid, methinks), I leaned a crowbar against the side of the house while chipping some conc away to run a drain. Picked it up again and... uhoh... there's now this permanent imprint. A closer look showed similar marks & worse all around the place, and it hasn't any residents yet!
Tradies may be rough in the initial stages, but most at the finishing stages take at least a modicum of care, far more than a gaggle of kids would anyway.
Ozwinner
(usually outside walls are loadbearing).
I repeat.
Should there not be a double top plate on a load bearing wall where the load is not carried directly over the studs. :confused:
Ps
I am not a builder but I think I read it in one of the council requirements. Somewhere....??? :confused:
TJI's (truss Joist incorporated) are used almost exclusively for floor joists here, though the web member is usually OSB, and the chords are usually 2"x2" not 2"x4" like in your photo :eek:. they are indeed very strong if used as intended. i can't see masonite bieng any worse than OSB in the presence of moisture.
their performance under fire load however is alarmingly poor. at relatively low structure fire conditions the glue delaminates the web from the chord causing acute and early floor collapse.
I doubt whether you`ll find many guys using kd hardwood for joists any more. Even they are never the same width and the do bow as well so you are forever packing or planing to get the levels. With these kind of joists they are dead straight, are the same width, can span much further. They do work and after the plasterboard is on you wont even think about it. I doubt whether they would be used or even get approved if the didnt work.
stef
The basic idea is quite sound, aeromodellers have been using the webbed spars like this for years. Very strong in compression for high loads but we use spruce spars with balsa webbing, call it an "I" beam.
I don't think it's the I beam idea people are objecting to, it's the use of masonite for the web. I beams have obviously been around for awhile, we're using some in our house but it's LVL, not this stuff. Dunno, I can't see why it would be any weaker than LVL. Similiar principle to a torsion box when you have a heap of them side by side under your floor. As long as they can't tip over, it should be strong enough.
Ryan's point is a good one though. My joists are going to be LVL beams and I suppose they will suffer the same fate in a fire. If the glue lets go it's just a bunch of pine veneers standing on edge. We're only single storey though, so maybe not such a problem as it would be in a two storey house. If it gets hot enough to melt the glue, it's probably going to be a knock down and rebuild anyway :(
Understand but just pointing out we use balsa for the web and get good results.
These prefab frames are usually fab to engineer’s specification with a thicker T/P than the studs e.g.; T/P 90 x 70 or 90 x 90, studs 90 x 45 and you can kind of see it in the first pic posted, the stud dose look thinner. Some can have DTP if the project builder’s customers want to change what’s on their tried and tested plans, to negate the need to re-engineer the whole building or to adhere tocouncil requirements (Not all councils would require DTP’s if any).<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /><o:p></o:p>Quote:
Originally Posted by DavidG
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P.S If some of you guy’s think what they make ibeams out of, are out there as far as building goes, you should watch some of the build show on cable and what they’re doing O/S<o:p></o:p>
Hey Al,
Could you measure up the joists , span length and spacing etc.
The dimensions could be handy for making overhead shelves in my workshop.
Changing subject slightly, I was talking to an engineering mate recently about those support trusses for sheds and carports made from pressed galv steel, zigzag structure between two U sections. He reckons the simple addition of bracing ply(6mm?) tek screwed to the face will dramatically increase their strength. Similar effect maybe as this masonite I-beam, in the direction of load.
Cheers,
I wont be back there until mid next week, Ill get some measurements if I remember. :pQuote:
Originally Posted by echnidna
Al :)
David, as you said, if the load onto the top plate is within a distance of 1.5 times the thickness of the top plate from the stud then the plate is not considered load bearing - just holds the studs in position.
If the load is towards the middle of the top plate span then the plate is designed for the load it has to carry. For example a rafter 3 meters long carrying a tile roof may require a 45*70 top plate. A rafter 6 meters long carrying an iron roof may require a 45*90 plate. A rafter 6 meters long carrying a tile roof may require a double 45*90 plate.
With a truss roof often a double plate is used on the outside walls not for strength but to lift the bottom chord of the truss away from the internal walls.
As well as the glue, what about when the heat from the fire causes the gang nail plates to expand and fall out of the timber, such as in trusses!Quote:
My joists are going to be LVL beams and I suppose they will suffer the same fate in a fire. If the glue lets go it's just a bunch of pine veneers standing on edge. We're only single storey though, so maybe not such a problem as it would be in a two storey house. If it gets hot enough to melt the glue, it's probably going to be a knock down and rebuild anyway :(
As part of our structure firefighting training now, there is a module on building construction that covers this type of thing
Grinner:D
I suppose the question is how often would a house that has been burned to that degree actually be patched up? I'd imagine that sort of fire damage would result in the house, or the damaged part of it, being pulled down and rebuilt, wouldn't it?
So is it really less about whether the house survives the fire and more about what fireys have to watch out for when entering a burning house? In which case, it makes bugger all difference to the home owner because either way it's a rebuild on the cards.
Grinner - do firemen really get to pull more girls?
Ryan would be able to provide a more informed comment than I can but I have some experience in major infrastructural construction - albeit well out of date (it's over sixteen years since I was involved in that industry).
One lesson I did learn was never to put too much faith in the attitude of the authorities towards new construction methods and materials and the supposed safety standards that are imposed upon them. When it comes to fire, no-one knows how a new material will perform until a major fire occurs. Most of the safety standards are created by committees comprised of a mixture of public servants and industry representatives. These are well-meaning people but they are making decisions based upon data that is frequently theoretical, speculative or empirically gleaned from small scale experimental studies. I know because I spent a bit of time supplying some of the data.
Most of the major changes in fire safety regulation have come about not because problems were foreseen and predicted but because disastrous fires, sometimes with major loss of life, have demonstrated the utterly unforeseen dangers inherent in some new method of construction.
There were examples throughout the 20th century. Some that I can recall (because I had to study them at various times) were:
- Firestone's factory at Akron, Ohio (use of bitumenised roofing material without fire breaks on massive roof spans).
- A leisure centre in the Isle of Man (use of plastic daylighting material)
- A chemical factory in the North-East of England (use of polystyrene insulation in high sidewalls)
One piece of Aussie ingenuity and foresight: the RAAF had an obsolete aircraft hangar (can't remember where). Some bright spark (pun intended!) came up with the idea of burning it down in a controlled experiment to learn how major open structures perfom in fire conditions. A great deal was learned from this.
Unfortunately, most observed wisdom about the fire performance of construction materials and methods is gained expensively and sometimes at great risk to firefighters and others.