IanMcD wrote:
Hi,

I want to get cracking on a loft conversion on a bungalow and would
like some help in understanding the particulars of the materials I'll
be needing.

I have a lot of internal solid walls and plan to place RSJs from the
gable to the internal walls and suspend floor joists from them. I
understand that to do this I need joist hangers, I've never used a
joist hanger, do they differ in sie according to the dimension of the
RSJ, and how are they attached to the RSJ?

What size is the RSJ? It is normal to have the RSJ the same height as the
timber floor joists and just 'notch' the timber joist so it sits inside the
'web' of the RSJ - ergo joist hangers are not needed

I also plan to extend supports vertically upwards from the rsj up to
the roof joists to support them intead of using the gigantic purlin
tha is in place. How are these vertical posts attached down to the
RSJ and upwards to the roof joist, is there some specialized bracket
involved here?

Personally I would not consider replacing the purlin with hangers - bearing
in mind the roof will weigh several tons (or tonnes) and you could cause
some serious damage to the roof in doing that - if you decide to go ahead,
then the section size of the timber hangers must reflect the roof load that
will be carried and this additional weight will then also be transferred
onto your new RSJs thus increasing the floor loading - remember that you
must also take into consideration any winter snow loading.

As a caveat to this, if you intend to fit some sort of a dormer window,
then the roof purlin will obviously have to be cut and a method of
supporting (trimming) the cut ends worked out to maintain the load carrying
integrity.

Finally, what mechanism is used to fix the RSJ itself in place. My
house is very long, 54 ft, so I plan to use two lengths of RSK, ie. 2
RSJs on each side of the house. I expect it is sunk into a hole
knocked out of the gable on one end and bedded in with concrete, is
that correct?

Near enough.

But then when I rest it on the internal solid wall , what is used to
hold it in place there?

Bricks cemented to the internal wall on either side of the RSJs - but if can
be done in one length, the nothing as the floor joists will hold it.

I understand I'll need to abide by BR , I'll get my architect friend
to double check what I'm doing along the way but I'd like these
questions answered to help me in planning work,and pricing and
ordering materials.

In view of the questions that you have asked, I would seriously agree with
an Architect having a look and advising *before* you start - and possibly a
structural engineer as well.

Thanks for helping an adventurous DIYer save 10,000 euros. (in
ireland)

Ian, just take care in what you are doing and take all the professional
advice that you can get with regards to roof and floor loading/designs as a
'bad decision' may cost you far more than the 10,000 euros that you are
trying to save.



Best of luck on the project,

Brian G