Kwality Konstukshun

[bennylaird]

Understand but just pointing out we use balsa for the web and get good results.

[Auspiciousdna]

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:

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>

<o:p></o:p>

<o:p></o:p>

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>

[echnidna]

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.

[Andy Mac]

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,

[ozwinner]

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.

I wont be back there until mid next week, Ill get some measurements if I remember.

Al

[ausdesign]

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.

[grinner]

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 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!

As part of our structure firefighting training now, there is a module on building construction that covers this type of thing

Grinner

[silentC]

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.

[Bodgy]

Grinner - do firemen really get to pull more girls?

[Driver]

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.

[Auld Bassoon]

I have to agree Al,

The quality (if that's the right word) of that assembly is worse than I've seen in the average-to-poor humpy!

The design principle seems to be alright (I'm not an engineer though, so not really qualified to comment), but it's that way it's been flung together...

Cheers!

[boban]

Have a guess which one costs more fellas.

You will find that the bodgy guys will be using pine joists.

I beam joists are better than solid timber in so many ways.

The photo you are looking at is called blocking. It stops the joists from falling over. Similar to the function of bracing. You can use metal strapping or solid timber. Not too much wrong with it.

If you want to see the difference, you only have to walk on this type of floor.

[ozwinner]

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:

Ok I see the question.????
I was standing in the stair well, no at an outside wall.
I can see where you can be confused by the piccy.

Sorry for any confusion.

Al

[Markw]

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.

Something that you might note is a number of the Australian Standards Committees seem to be populated by more than a fair number of commercial interests which gives a lop sided bais to monetary interest.

The one I notice most is SF/15 (height safety) which has only a couple of user representatives whilst the bulk of the committee are from manufacturers each with a supposedly different claim to representation but in the end generally making decisions which would seem to benefit manufacture and not necessarily the end user.

Take a look at who ever approves these types of structures in the first place and see if there is a relationship between manufacture and the approval process.

[Marc]

Not forgetting the twin towers. If the I beam had been riveted to the outside structure, the towers would still be standing. Believe it or not the I beams where sitting on the outside frame and held in place by gravity.