extending joist hangers to steel beams

Hi,I am having to locate the steel supporting beams 15inches above the required floor joists to the loft conversion in progress.The joists are 9x3 and I was hoping to hang them using standard long leg joist hangers,bolted to the top of the steel.My problem is,due to the height of the supporting beams i am unable to find a joist hanger of the required length.Does anyone know if its possible to extend the legs of the hangers or where a suitable hanger can be found.
Thanks Mal.

 

Thanks Bob.If that method is acceptable to the building inspector,ill use it.The supporting beams are sat either end,on other steel beams which had to be put in above existing lintels across window openings.Rather than disturb the below ceiling level brickwork by putting in padstones at a height which enables normal hangers to be used,i chose to introduce these above that level into the loft area gable ends.This is a bungalow loft conversion,so as the main beam positions are used to create both the walls and roof supports,the only problem i had was the depth i had to hang the floor.I did have one or two ideas myself ,but your method i can see,will locate the hangers in an easy to level position.Many thanks, Mal.

 

Thanks for replying,Id be obliged for the link Trench.
Jonah,ill look into the cleating method you mention and if possible ill use it,if not ill go with Bob and also include the input from Trench and B/C.The steels being used are 178x102x19ub over the window lintels.The main beams are 356x171x19ub,which span 24ft before meeting the next padstoned support,(cimney breast and internal garage wall)then carrying on for a further 12ft to the outside wall.Trusses are the modern trussed variety and will need pretty much dismantling.So i intend creating a full skirt of 18mm ply from the web of the beam to the top of the trusses,I can then both support and restrict movement of the new joists and use the skirt bottom to act as an extra support for the ceiling below,obviously i will be supporting the rest of the trusses in the usual way.Perhaps B/C could let me know if that sounds acceptable. thanks all Mal.