Structural Wall?

[dennis]

Correct, you are getting there. A builder that does something they don't know how to do or isn't covered by their insurance is a cowboy.

As I said, it obviously wasn't a structural wall.

[The Natural Philosopher]

No, it was I discovered later, political.

The prime customer was in fact a german company, and they insisted that instead of an FM tuner head made in Japan, we used a German one made by IIRC Siemens.

When I used that the noise level increased. I was under extreme pressure to finish other parts, so apart from knowing where the cause lay, I could not actually say why.

The Good Germans refused to believe that anything made in Germany could be so crap, so the consultant was called in to make an unbiased report. Most industrial consultancy seems to be more about solving political problems than technical.

Anyway, after all that I had to dive into the blasted tuner and work out why it was noisy.

I found two complete and utter balls ups in the design. It was an FM tuner head.

The first utter balls up was that an unsmoothed zener diode was being used to stabilise the voltage of the oscillator. Very good, as it meant there was no chance of drift with supply voltage, HOWEVER zener diodes are wonderful noise sources..which essentially caused the oscillator to jitter, giving the noise. The addition of a very large capacitor instantly removed that. I was able to demonstrate the actual noise levels equated to the frequency to voltage slope times teh theoretical noise of the zener..took a two day bit of math, but the Germans like lots of numbers.

The second fault was that the stupid designers had used a ferrite cored oscillator core. Ferrite is nice stiff, but it varies its reluctance? I think that's the right word - when in a magnetic field, and the mains transformer in this design had to be close..we retrofitted 1000 brass or aluminium cored cools to these stupid tuners. I would say that 'good german tuner' set the project back 3 months plus, and cost thousands of man hours.

Oh, don't get me wrong, I trusted the consultant: It was just that in terms of getting an answer, there were quicker ways. It didn't invalidate his way at all, juts made it seem very expensive!

Its not possible in structural terms to remove a wall to see if the house falls down, and then put it back. HOWEVER even structural engineers can be better than this suggests., I had one round to look at my roof and his answer was after 15 minutes looking at the loft, that no, I couldn't put anything heaver than shingles on the roof, and he was surprised that the bits of Christmas tree and old hoe handles even kept that up.. ;-)

Was there anything about the house at all that was sound? 'You will find out when you renovate it'

And I did, and the answer was 'nothing that wont be more expensive to keep than to demolish'

BUT even there, the builders used had a pretty good idea of what would take what sort of load. When you work around structures, and have seen some fail, you 'know' that a wood beam will or wont take that many bags of cement loaded on it, or being hoist by it.etc etc.

I 'know' that a 4x2 will take a couple of tons central over a 9ft span..just..because I have lifted that much on it. I wont ever do it again mind you, because it didn't look quite the same afterwards.

So I wouldn't e.g. use a 4x2 to support a solid wall above it, on its own.. of any height. I 'know' that a pile of bricks abut a meter cube weighs about 1 ton and a bit, because I had to put them in two landrovers and drive them, and it wasn't fun, three trips in all, and still hairy..

[The Natural Philosopher]

The cost of a structural engineer, whose report is enough to validate insurance policies, is a couple of hundred quid usually. In many projects its a trivial amount and all arses get covered. And if things go wrong, insurance pays out. You tried your best to reduce the risk.

But its pretty easy to see if a wall IS load bearing or not, by going up and seeing what is on top of it.

After all, that's really what the engineer does.

He doesn't have access to better data than the handyman, he is just able to interpret it better. And most of all, he actually asks the question 'will it fall down' where the handyman probably assumes it wont.

In engineering, provided you ask the right question, the answer is actually usually simple to arrive at. The major disasters that happen in engineering projects are almost always because the right question was not asked.

Once you say 'will the house fall down if I pull that wall?' you are already 90% of the way there.

The handyman isn't a structural guy: A builder is. The builder may be expected to ask the question, the handyman is not.

>

[The Natural Philosopher]

Ultimately in a building, there are no others.

Except maybe in prestressed concrete, where the stress is in the form of tensioned steel, or in groundwork where its soil movement due to humidity changes, and occasionally one takes wind stress into account, but these are specialise areas. In the end the rest of the forces are all due to gravity. They may not be straight down, that's all.

Buttresses are directly about the roof weight on arched, ridged or domed rooves. They are there because masonry does compressiion wonderfully, but is crap in tension, and hence bending.

[The Medway Handyman]

And what would they be Dennis?

[The Medway Handyman]

I'd love to see such a definition, but alas its prolly just Dennis making things up again.

[Steve Walker]

*plonk*