Steve wrote:

Yes, I see that but wouldn't the fact that the beam was drilled only in
the neutral axis i.e. along the centre where I believe that the beam was
neither under compression or expansion make this OK? I would also clamp
the edges tightly whilst the glue sets.

you have to be a little careful where you drill - i.e. not to close to
the ends or you risk allowing the beam to split.

You are right. I just have an inherent distrust of nails, even big ones!

Plenty of houses have stood for hundreds of years held together by
little else. ;-)

Doable, but possibly overkill. If you wanted a beam stronger than a
pair of timbers side by side, then the next option would usually be a
flitch beam[1] (i.e. a pair of beams with a steel plate sandwiched
between them, and bolted together). Not sure how realistic that is on
only 4" of depth though.

I did not know about flitch beams. Maybe my thoughts about deep depths
of plywood sandwiched between the joists are my primitive way of
re-inventing the wheel :-) However that has got me thinking that this
might be the neatest, most elegant and best solution. Presumably a steel
stockholder would cut and 'passivate' them for me.

Indeed they will - they will drill them for you as well. Superbeam will
model them for you as well.

[1] Example 8mm steel plate flitch (with red passivated coating):

http://www.internode.co.uk/loft/images/flitch.jpg

Yes, I see it there - what does it have to support?

The one in the photo was I believe "E":

http://www.internode.co.uk/temp/beam-layout.gif

Which as you can see gets a share of the load of pretty much everything
at the front of the loft, including the previously pictured dwarf wall.

So 0.8kN/m uniform load from the floor, a 5.7kN point load at 0.7m from
beam F (stringer that carried the main front floor joists - present
because getting at the existing lintle would have been too difficult),
and a 11kN point load at 2.8m from beam C (triple joist) that carried
two sets of floor joists, and a share of at least three partition
walls.... oh and a bit of roof.

So all in all about a nominal 20kN or two tonnes in total. The centre
span deflection was calculated at just under 9mm.

In context:

http://www.internode.co.uk/loft/floor.htm


--
Cheers,

John.

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