"John Rumm" wrote in message
...
Andrew Barnes wrote:
John

It seems that you have a lot of knowledge regarding loft conversions. I
am
soon to move into a new house and intend to convert the loft. Would you
be
able to offer me advice on the job, it will be strictly DIY!

I am happy to share what I have learned. I don't claim to be any kind of
expert, since my actual experiance of doing loft conversions now runs to
a grand total of one! Needless to say yours may be somewhat different.
As I am now nearing the end of my project I hope I have encountered most
of the issues that need to be dealt with along the way.

Perhaps when the project is complete, I will knock up a web site
covering the process, if there is enough interest.


--
Cheers,

John.


Hi John

from your pics, this all looks pretty similar to my own house, and I would
certainly be interested in your experiences with this project.

Converting the loft is on my list of major projects to look at, but at the
moment I'm concentrating on the plans for the rear extension first.

cheers

David

Christian McArdle wrote:

Yes, that looks similar to my proposed solution, although on a grander scale
and with the stairs in a different location.

The scale was a grad as would fit (without a front dormer) in my case
;-) Got two decent sized bedrooms and a shower room out of it.

Has anyone got a definitive answer as to whether the steel joists can be
"hung" off the structural beam and how?

I am sure they can - but I don't know what the prefered way is. ISTR
that when watching people building steel beam floors on grand designs
and the ilk, the beams were flanged on the ends and they bolted them
together.


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

Christian McArdle wrote:

I put 50+30mm in total on ours, and the BCO passed it yesterday ;-))


A quick check of the tables shows you're right. The 50+30mm of insulation is
absolutely right on the nail for 0.3. 75mm wouldn't have done it.

Oddly enough, our plans were drawn with 50 + 25 and the BCO passed those
at submission time as well. I only used 30 because that is what the
supplier had (I ordered 25, he delivered 30 at no extra cost)

Remember that the u value of 0.3 applies to the whole roof - not just
the insulation. Hence having calculated the u value for the insulation
you need to adjust that to account for 2/3 layers of tiles, under felt,
and battons. This will usually make up for the 5mm reduction in insulation.

The problem come when you install between rafters only. They publish figures
for 75mm and 100mm, with the 75mm being well out at 0.36, but the 100mm

Yup, witout the overall cover of the under layer you loose a fair bit of
benefit because of the bridging effect of the rafters.

being well in at 0.28. My intended roof (75mm between and 25mm underneath)
gives 0.25.

That should do it ;-)


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

"Christian McArdle" wrote in message
et...
If you want 12.5mm more height, you can get the 25mm insulation with
paper
rather than foil covering and then plaster skim this.

I haven't heard of this. Is there a brand name for this product? Sounds
just
the thing.

Christian.

Not on it. I've already used ten sheets and have got 40 sheets of 120mm
coming to do a barn roof. I'll ask them who makes it when they deliver.
Made the mistake of putting it up then plastering, when what I should have
done was plaster the boards flat on the floor, put them up then repair the
joints and fixings.

Christian McArdle wrote:
that when watching people building steel beam floors on grand designs
and the ilk, the beams were flanged on the ends and they bolted them
together.


Something like a top hat section? Or a flanged box?

I was thinking more along the lines of where you want to join a typical
"I beam" profile perpendicular to another beam. The end of the beam to
butt against the side of the other, terminates in a drilled flat plate
across its end surface to allow bolts to be inserted parallel to the
beam and through the beam it is in contact with. This often seems to be
done with small right angle brackets that bolt to the end of the beam.

Plan:

| |
| | +================
| | | B |
| | |--- |
| A | =====| C
| | |--- |
| | | B |
| | +================
| |

A = Beam 1
C = Beam butting onto A
B = right angle plates bolted to end of cut away section on beam C that
allow it to mate with the cross section profile of A and be bolted to it.

Profile:

+-------+ +=================
| |----|
| | |
| | |
| | |
| |----|
+-------+ +=================


I presume there are a number of ways of doing these joints. It may just
come down to the preference of the fabricators.

I don't recall ever seeing them weld the beams together but that does
not mean it never happens. There was one build I saw where they were
"fettling" the fit with a flame cutter!

(I get the feeling that BCOs would be less keen welded joints since it
will end up producing a less deterministic structure as the weld quality
is far harder to control and model when doing calculations. Whereas
shear loadings on bolts of a known size is simpler to deal with).

In many loft conversion where steel beams are used, they still have
wooden ones strung from them. In these cases it seems quite common to
bolt smaller wood beams down the sides of the I section (filling in the
recess) so that ordinary joist hangers etc can be nailed to the main
beam. Probably not much use in your case where you could end up with the
exact opposite - a large wood beam at the eves, with smaller box section
steel beams strung from it.

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

I was thinking more along the lines of where you want to join a typical
"I beam" profile perpendicular to another beam. The end of the beam to
butt against the side of the other, terminates in a drilled flat plate
across its end surface to allow bolts to be inserted parallel to the
beam and through the beam it is in contact with.

Got you, although that would only work with the 76mm RSJ section, assuming
that could be obtained. I wonder what they would do with 90mm square box
section for the joists? The beam, of course, could be any material or shape,
although will probably be greater than the joist height, as it is taking far
more load. My conservatory base appears to use welded box section, although
this is done under ideal factory conditions, not suspended upside down up
some scaffolding.

Indeed, modelling with the joist loadings and weights as a uniform load
(rather than as individual point loads), it suggests a 178x102 UB, or a
300x50 timber 10mm flitched beam. It can't come up with a suitable timber
only member, as it seems to be limited to 300mm depth. This, of course,
assumes that it is only fixed at the party wall ends, whilst it may be
possible to have additional bearings at the edge of the bay window.

Christian.

In article , Christian
McArdle wrote:
Indeed, modelling with the joist loadings and weights as a uniform load
(rather than as individual point loads), it suggests a 178x102 UB, or a
300x50 timber 10mm flitched beam. It can't come up with a suitable
timber only member, as it seems to be limited to 300mm depth. T

Minor digression: assuming that the 'it' is SuperBeam, there's a little
button on the timber page labelled 'Change Std Dims' which contains a list
of depths that the program works through when trying to find a suitable
section: you can add larger one on the end of the list or delete unwanted
entries - though whether you can readily find timber greater than 300mm is
another question. Alternatively just pick a depth (e.g. 400) and type it
in.

--
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

Minor digression: assuming that the 'it' is SuperBeam, there's a little
button on the timber page labelled 'Change Std Dims' which contains a list
of depths that the program works through when trying to find a suitable
section:

Yes, I'd read somewhere in the instructions about this, but then wondered
when I'd last seen wood deeper than a foot in one piece. I imagine that if
you can find it, it would be so expensive that steel would surely be the way
to go.

Christian.

Christian McArdle wrote:

Yes, I'd read somewhere in the instructions about this, but then wondered
when I'd last seen wood deeper than a foot in one piece. I imagine that if
you can find it, it would be so expensive that steel would surely be the way
to go.

From my experiance, flitch beams are DIYable without mechanical lifting
(although you will want a friend to help get the flitch plate up a
ladder!) I would expect there to be a crossover point in cost as well
where the flitch will start getting cheaper than the more exotic timber
sizes.

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

From my experiance, flitch beams are DIYable without mechanical lifting
(although you will want a friend to help get the flitch plate up a
ladder!) I would expect there to be a crossover point in cost as well
where the flitch will start getting cheaper than the more exotic timber
sizes.

Agreed. However, unless it significantly helps the construction process, I'd
be inclined to just go 100% steel. It isn't expensive in the scheme of
things, provided there's a way of hanging SBS joists off a steel beam.

Christian.

Christian McArdle wrote:

Agreed. However, unless it significantly helps the construction process, I'd
be inclined to just go 100% steel. It isn't expensive in the scheme of
things, provided there's a way of hanging SBS joists off a steel beam.

Makes sense. Why not talk to a locak steel supplier/fabricator and see
what they recommend? The place I found to supply the steel I needed
where quite helpfull, and pretty much new what to do without any prompting.


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

Christian McArdle wrote:
A quick play with SuperBeam appears to indicates for my proposed loft
conversion floor (4m span, 2kN/m2, 500mm spacing), I need either:

snip
To take this thread off in a completely unexpected direction.

If it was possible to make a composite one-piece floor, say for example,
25mm plywood, it seems that this might be adequately strong.

"Christian McArdle" wrote in message
et...
Minor digression: assuming that the 'it' is SuperBeam, there's a little
button on the timber page labelled 'Change Std Dims' which contains a
list
of depths that the program works through when trying to find a suitable
section:

Yes, I'd read somewhere in the instructions about this, but then wondered
when I'd last seen wood deeper than a foot in one piece.

Probably as a whole tree used for a beam in a barn conversion.

"Ian Stirling" wrote in message
...
Christian McArdle wrote:
A quick play with SuperBeam appears to indicates for my proposed loft
conversion floor (4m span, 2kN/m2, 500mm spacing), I need either:

snip
To take this thread off in a completely unexpected direction.

If it was possible to make a composite one-piece floor, say for example,
25mm plywood, it seems that this might be adequately strong.


Easily strong enough, in that it wouldn't fail. But surely it would deflect
more than is allowed.

Hi John,

How did you fix the timber insert to the flitch, did you use a glue or bolts or both?

Regards

Ian

IanMcD wrote:

Hi John,

How did you fix the timber insert to the flitch, did you use a glue or
bolts or both?

(email sent)

This thread happened so long ago it has expired from my news server!

The quick answer is that a flitch is a steel insert in between two
timber beams. Fixing together is via bolts though holes drilled right
through the lot. Typically 12mm, with plate washers either side.

Other beams can then be hung from the flitch using joist hangers nailed
on with square twist nails in exactly the same way as you would use them
on a conventional wood beam.



--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/