I was at a trade show at the week-end and saw a couple of new building
methods and was wondering if anybody on the list have used them and if
so what were their experiences.

The first was an engineered flooring joist it was made from 75mm
square timber frame with steel diagonal ties and occasional 75mm
square reenforcing. It came lengths up to 5M. It seemed like a good
idea as it allowed easy running of plumbing and electricals through
the joists without drilling as they were hollow and it is supposed to
have better flex and load carrying characteristics

Joist Side on, all horizontal and verticals 75mm timber, diagonals
steel ties.

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The second item was a building block made from extruded clay it was a
sandwich of a 125mm inner block, 100mm polystyrene insulation and 75mm
outer block. They are used alot in Finland apparently. They are fixed
using an adhesive rather than traditional sand/cement mortar. They
were very light but seemed flimsy to me.

In article , Michael
Walsh wrote:
The first was an engineered flooring joist it was made from 75mm
square timber frame with steel diagonal ties and occasional 75mm
square reenforcing. It came lengths up to 5M. It seemed like a good
idea as it allowed easy running of plumbing and electricals through
the joists without drilling as they were hollow and it is supposed
to have better flex and load carrying characteristics

Catnic tried an idea like this about 20 years ago. The diagonals were
V shaped galvanised pressed steel, with the ends and point being
stamped out to form nails like the plates used to assemble trussed
rafters and pressed into the top and bottom members in a similar way.
They didn't catch on.

The second item was a building block made from extruded clay it was
a sandwich of a 125mm inner block, 100mm polystyrene insulation and
75mm outer block. They are used alot in Finland apparently. They
are fixed using an adhesive rather than traditional sand/cement
mortar. They were very light but seemed flimsy to me.

I would wonder about the resistance to rain penetration. In some
respects a climate where it stays below freezing for months on end is
less demanding that our freeze/thaw driving rain winters.

--
Tony Bryer SDA UK 'Software to build on' http://www.sda.co.uk
Free SEDBUK boiler database browser http://www.sda.co.uk/qsedbuk.htm

"Tony Bryer" wrote in message
...
In article , Michael
Walsh wrote:
The first was an engineered flooring joist it was made from 75mm
square timber frame with steel diagonal ties and occasional 75mm
square reenforcing. It came lengths up to 5M. It seemed like a good
idea as it allowed easy running of plumbing and electricals through
the joists without drilling as they were hollow and it is supposed
to have better flex and load carrying characteristics

Catnic tried an idea like this about 20 years ago. The diagonals were
V shaped galvanised pressed steel, with the ends and point being
stamped out to form nails like the plates used to assemble trussed
rafters and pressed into the top and bottom members in a similar way.
They didn't catch on.

What were the reasons for it not catching on? Just too new, people too
suspicious of something unfamiliar? Presumably it had been tested and proved
to be suitable.

Mary

In an earlier contribution to this discussion,
Michael Walsh wrote:


Joist Side on, all horizontal and verticals 75mm timber, diagonals
steel ties.

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| \ / \ / | \ / \ / | \ / \ |
| \ / \ / | \ / \ / | \ / \|
---------------------------------------

So what was the overall size of cross-section? Do you have a feel for size
of ordinary wood joist it would replace - in terms of equivalent strength
and bending siffness?
--
Cheers,
Set Square
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In article ,
Mary Fisher wrote:
What were the reasons for it not catching on? Just too new,
people too suspicious of something unfamiliar? Presumably it
had been tested and proved to be suitable.

At a guess (a) cost: though the builders probably weren't
factoring in the time saved in drilling holes for servicing,
sorting out twisted joists etc; (b) need to be ordered to length
probably several weeks ahead, whilst for 8x2 you can phone a
timber yard and they'll be delivered tomorrow; (c) they probably
needed somewhat more careful handling which cannot be relied on
on many UK sites; (d) they might (though might not) be damaged
by overloading - as might occur when the bricklayers have loads
of bricks or blocks stacked on boards across the joists.
Ordinary solid timber joists might deflect a but they'd spring
back.

(b) and (c) apply to trussed rafters too. With these though the
time saving is more obvious. In my BCO days we did have trouble
sometimes with badly stored trusses being damaged.

--
Tony Bryer SDA UK 'Software to build on' http://www.sda.co.uk
Free SEDBUK boiler database browser
http://www.sda.co.uk/qsedbuk.htm

"Tony Bryer" wrote in message
...
In article ,
Mary Fisher wrote:
What were the reasons for it not catching on? Just too new,
people too suspicious of something unfamiliar? Presumably it
had been tested and proved to be suitable.

At a guess (a) cost: though the builders probably weren't
factoring in the time saved in drilling holes for servicing,
sorting out twisted joists etc; (b) need to be ordered to length
probably several weeks ahead, whilst for 8x2 you can phone a
timber yard and they'll be delivered tomorrow; (c) they probably
needed somewhat more careful handling which cannot be relied on
on many UK sites; (d) they might (though might not) be damaged
by overloading - as might occur when the bricklayers have loads
of bricks or blocks stacked on boards across the joists.
Ordinary solid timber joists might deflect a but they'd spring
back.

So the builders need to adapt their techniques ... that happens in all
trades with all new products.

In my experience :-)

Mary

(b) and (c) apply to trussed rafters too. With these though the
time saving is more obvious. In my BCO days we did have trouble
sometimes with badly stored trusses being damaged.

--
Tony Bryer SDA UK 'Software to build on' http://www.sda.co.uk
Free SEDBUK boiler database browser
http://www.sda.co.uk/qsedbuk.htm

Mary Fisher wrote:

"Tony Bryer" wrote in message
...

In article , Michael
Walsh wrote:

The first was an engineered flooring joist it was made from 75mm
square timber frame with steel diagonal ties and occasional 75mm
square reenforcing. It came lengths up to 5M. It seemed like a good
idea as it allowed easy running of plumbing and electricals through
the joists without drilling as they were hollow and it is supposed
to have better flex and load carrying characteristics

Catnic tried an idea like this about 20 years ago. The diagonals were
V shaped galvanised pressed steel, with the ends and point being
stamped out to form nails like the plates used to assemble trussed
rafters and pressed into the top and bottom members in a similar way.
They didn't catch on.


What were the reasons for it not catching on? Just too new, people too
suspicious of something unfamiliar? Presumably it had been tested and proved
to be suitable.

Basically its actually more expensive than just whacking down 6x3 softwood.

To make the most out of all this stuff you need a slightly different
approach to design.

If you mass produced a complete celing/floor using them, so the blokes
on site just laid it en bloc, it might be worthwhile.

All this clever stuff means you have to change teh way things are done.
Pre-fabbing is vheaper, but you have to think about plumbing and wiring
eairler, and have things like cranes on sie to lift in prefab chunks.




Mary

The first was an engineered flooring joist it was made from 75mm
square timber frame with steel diagonal ties and occasional 75mm
square reenforcing. It came lengths up to 5M.

Wow, what was the name? I'd really like more information on this one.

I'm currently considering steel to get a 4m span under 100mm. A wood based
product would probably be easier to install than steel, provided it can be
approved for 30 mins fire resistance with only plasterboard below.

Christian.

In article ,
Christian McArdle wrote:
Wow, what was the name? I'd really like more information on
this one.

I'm currently considering steel to get a 4m span under 100mm.
A wood based product would probably be easier to install than
steel, provided it can be approved for 30 mins fire resistance
with only plasterboard below

It wouldn't help you on height. IIRC the Catnic ones I referred
to had top and bottom chords of something like 75x38 flat (one of
selling points was lots of nailing room for floor deck and
ceiling) and the overall depth was about 300mm. So it had the
stiffness of a 9x2 but weighed half as much.

With timber joists deflection is nearly always the limiting
factor, and stiffness is proportional to the cube of the depth.
Keeping the width and joist spacing the same, if you reduce the
size from 6" to 5" the deflection goes up by (6/5)^3 = 1.75 and
from 5" to 4" by (5/4)^3 = 1.95 - i.e. 2 x 50x100 = 1 x 50x125

--
Tony Bryer SDA UK 'Software to build on' http://www.sda.co.uk
Free SEDBUK boiler database browser
http://www.sda.co.uk/qsedbuk.htm