Joists sitting on pre-stressed concrete lintel

[pls1]

As per the subject, I'm curious to know if the above arrangement is allowed. Situation is a single skin load bearing wall (supporting 1st floor only, no wall above). Lintel has been installed and brickwork below knocked out. Three of the joists from the floor above rest directly on the lintel now (packed with slate). Lintel sits on 20cm bearings each side.
Pic here- http://db.tt/1gi5A5bn

 

[tony1851]

The very shallow (75mm) pre-stressed lintels are not intended for 'point' loading from such things as floor joists. This is because these lintels are designed to achieve their strength by being 'built-in' with brick/blockwork above; the adhesion of the mortar to the top of the beam distributes some of the load into the walling above and so helps the beam. This would not apply in your case.

Having said that, the span does not look great (possibly door width?) so in practice you could well be OK. Personally, I would have used a 4" x 4" timber lintel instead.