loft conversion _without_ strengthening roof?!?

wibbled on Sunday 22 November 2009 19:05

Let me see... This newsgroup has been here for over 15 years. You've been here (apparently) for 3 days. We'll discuss what we like and if you don't like it, you've already had some suggestions what you can do.

Many things here have untold numbers of variables.

I'm struggling to understand how an established builder can think pouring SLC onto asphaltic floor adhesive is a good idea. Or how the same person can think balancing a lintel on a single column of celcon blocks (1/2 length) with two weedy screws as wall ties is good workmanship.
The answer is simple. Some professionals are lazy/bodgers/clueless/wankers or combinations thereof. I'm sure your claimed profession is far from immune from having its share of lazy/bodgers/clueless/wankers.

So?
--
Tim Watts

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Tim W wrote:

What is the span of the lintel and the loading? What is the size of the block pier and the compressive strength of the block / mortar? Did the pier have to be block bonded into the adjoining masonry?
Is this a residential or commercial/industrial application?
Who supervised the work? Did the builder have drawings to work to?
Who did the structural calculations? Did the job get Building Regulations approval?
Do you understand the difference between trade membership and professional qualifications?
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Shhhhhhh ...... X Factor's on TV now and if them horrible twins go then there's only one more oink left to go to make my day (hint)
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wibbled on Sunday 22 November 2009 19:56

I understand the difference between a useful human being and a troll.
Been fun, but have real work to do now. Bye...
<plonk>
--
Tim Watts

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Yeah, bored now - and Top Gear's just started
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geoff

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Yeh - and it's got dribble's 'prius' on it.
--
*The first rule of holes: If you are in one, stop digging!

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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And "me"
--
geoff

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Do tell.
--
*Indian Driver - Smoke signals only*

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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They christened the car "geoff"
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geoff

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erm ..... "Err sorry - why should I believe in your god and the baggage contained therein."
Ash
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Term adopted from the man on a stick
now you see the danger ...
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geoff

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Roof wrote:

No I would disagree. Where the question is general - as per the OPs, the advice can only be general - explain some of the options, what further information is needed, and where you could go for advice. In some cases that is all a poster needs.
In this particular example, that seems to be pretty much what he got - advice where to find out more information, and some explanation that the key worry he had (strengthening the roof structure), may actually have been less of an issue that other factors that had not occurred to him such as the floor suitability. These don't seem to be disproportionate or irresponsible responses - and I note that you have not provided substantially different or contrary guidance.

Again no, that makes no sense. When a question comes that is either sufficiently specific, or it can be refined into one that is by subsequent questions and answers, then it is entirely possible to provide as detailed an answer as a paid professional might given the same information. Whether one would do so for something as broad in scope for a complete loft conversion is doubtful - since after all, we don't get paid to work full time on this, however it is entirely possible that one may seek advice designing a structural element such as a floor joist or lintel etc for which an accurate answer could be given relatively quickly and with little risk.
To use your analogy, you seem to be saying that advising how to wire a plug is ok, but for a consumer unit replacement you need a professional. The latter is far more complex than the former, but its not black magic - it can be taught and learnt.

There will always be a risk of misunderstanding regardless of the route taken to advice. That can happen in newgroup posts (possibly supported by detailed photographs, plans etc), and direct briefs to structural engineers. As I said before, you are responsible for deciding how to use any advice you receive. As a paid professional you are also assuming that when you answer a specific question that the persona acting on the answer actually understands it - alas that does not always happen here or in real life, but I am sure it does not stop you answering.
(odd how houses are now "very simple structures")
--
Cheers,

John.

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I brought in my own structural engineer who reckoned they'd put a 'trainee' on the job and this was part of his thesis. As I said not many would expect three pages of drawings and calculations for a padstone to support a steel in a 9" outside wall.

Sadly 'getting a pro in' is no guarantee of finding the very best solution. As in my case other pros - including the local council ones - disagreed with his approach. And expected me to mildly pick up the several thousand extra costs.
--
*The only difference between a rut and a grave is the depth.

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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On 20 Nov, 22:52, Roof wrote:

Don't give out any, then.
Owain
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Roof wrote:

As an engineer (like you), and as someone who has actually built a loft conversion themselves (like you?), I am probably better qualified than most to offer guidance.
Regarding my comments above, firstly: "there may be no requirement for strengthening the roof structure". I said this to highlight that strengthening the roof structure may not be required, so is not in itself something to get worried about without further information about exactly what has been done and how.
Are you suggesting that there *always* will be a requirement? If not then we are in agreement it would seem. If so then I would have to doubt *your* knowledge of the subject.
For a simple loft conversion that stays within the envelope of the existing roof, and where that roof is of traditional joinery construction (i.e. not trussed) there will be little need of structural changes to the roof space in many cases. You may need to double the joists either side of a roof window. You can rely on LABC advice here, or do the calculations. You are generally adding relatively little loading by way of insulating and lining the space.
If you start adding dormers, removing purlins, or converting a hipped roof to gable wall then obviously the situation in different, as would be the case if you have a "forest of matchsticks" style trussed roof.
Moving on to the floor; I said "however there will be one for strengthening the floor".
It would be very rare to find a loft floor that was capable of taking a loading of 1kN/m^2 or 0.8kN/m of distributed linear joist loading (400mm ctc) without additional strengthening.
--
Cheers,

John.

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perhaps this is a bit too "real world" from your ivory tower? :>) I've just read this through and I'm not that surprised that your training etc leads you to that statement...whether I agree with you is a different matter...

which is what exactly?

naturally!
I concur on that one..
JimK
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On Fri, 20 Nov 2009 18:46:04 +0000, Roof wrote:

Do you have any experience of fall-out shelters?
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Jules wrote:

Do you?
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On Fri, 20 Nov 2009 22:54:00 +0000, Roof wrote:

No, and I don't need any...
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You are a trainee Steve Firth AICMFP.
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