DIY partial loft conversion

Dear All,
I'm planning a loft conversion at some point in the future, but before I call an architect and start paying by the hour, I though I'd canvass some opinions.
Details :
My loft space is approx 30' x 14', and it is a new build so the trusses are made from 3"x2", and they rest on 4"x2" battens (or should that be 2"x4"?) on top on the walls. There is about 9' at the apex, and the trusses are a simple triangle, except for a single vertical that goes from the apex to the mid point of the joist. There are no supporting walls under this mid point, as far as I am aware, in fact I'm sure all the walls on the first floor are simple stud walls (it's not a posh house)
What I am thinking :
I don't have the cash, time or inclination to do (have done) a full conversion, but storage space would be good. I don't want to board the loft, then remove it in X years time when I do come to do a conversions.
What I'd like to do is get plans drawn up by an architect for the full conversion, and have them approved by the local planning office. Then, go ahead and install just the beefed up floor (adding water, power etc as per the plans) leaving the roof/dormer/etc in tact. Then in X years time, when cash/inclination allows, complete the conversion.
Concerns :
If architects plans are approved, do they have a "to be implemented by" lifespan. I.e. if I do the floor, then in 8 years time when I come to do the rest find the floor no longer meets ever tightening regs, that I'm stuffed and cant finish it.
Practicalities :
I'm a pretty well seasoned and competent DIYer, and to keep costs down would do as much as the labour as possible (I am aware of limitations and need for proper help/advice though).
A local builder friend suggested that floor beam depth rule-of-thumb is "halve the span length in feet, and add two inches" ... i.e. for a 14' span, I'd be looking 9" x 2" x 14'. Several set of architects plans he showed me seemed to satisfy this rule, and were on 300mm pitch. That's ~30 of these 9" x 2" x 14' beams.. Eeeek.
Someone else suggested that, to make the job more practical, it might be possible to use 5 (say) 6" steel I beams width ways (14'), and then put 6"x2" x ~7' wooden joists between them (obviously subject to calculations). The steels would be about 100kg each, and about 95 (according to some web based research). Although it might take a days work for a few strapping friends and my builder buddy to get those steels in, it would make the rest of the job a bit more manageable for me on my own (I can manage 7' 6"x2" quite happily). Also lots of steel does sound closer to my usual ethos of "why risk using a 1 1/2" x 8 screw when a M12 raw bolt will *definitely* do the job"
Any thoughts opinions appreciated
Cheers
Chris
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On Tue, 13 Sep 2005 17:35:20 +0000 (UTC), a particular chimpanzee
keyboard and produced:

<snip>
For what you describe, you'd be better contacting a structural engineer first to see whether it is feasible. A loft conversion in a trussed rafter roof virtually means constructing a new roof, and as you have found, the only loadbearing walls are the external ones.
--
Hugo Nebula
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"Wall plates".

The ceiling (and water tanks if you have them) are effectively hanging from these.
--
Andrew Gabriel

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Chris Styles wrote:

Stud walls are not conclusively non load bearing, although it is not uncommon to have trusses completely self supporting.

Once it is "started" there is probably no need to worry.

It is certainly possible to DIY, BTSTGTTS.

Have a play with superbeam and you can do the calcs to see what you actually need. You may also find it simpler to stick a steel or flitch beam across the middle of the span as a stringer and hang half length beams off that.

Yup, there are loads of variations that might work.

There is a fair bit of background on the conversion I did here: http://www.internode.co.uk/loft /
and dealing withthe floor structure in partiucular here: http://www.internode.co.uk/loft/floor.htm
--
Cheers,

John.

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Chris Styles wrote:

If it's within your "permitted development" and depending on what windows you want to put in then you will probably not need planning permission. Most councils will send you a handy booklet on planning if you give them a ring, or try their web site, e.g. http://www.hullcc.gov.uk/buildingcontrol/leaflet_04.php or http://www.stoke.gov.uk/ccm/navigation/environment/planning/permission-guide/loft/.
Building regulations is the one to worry about.
MBQ
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