Dropped Ceiling question: Am I crazy? How would you do this?

[c0wb0y]

Hey folks, just want to get your thoughts on a loft conversion in an Edwardian semi where a ceiling drop was requested after the builder had bedded the wall plate and fitted rafters. Wall plate can't be lowered as the owner wants to keep Fascias, Soffit and Gutters (FSG) in-line with neighbours.

The builder seems to think its ok to Chem fix or Raw Bolt two lengths of 7x2 over a 6.2m span to create a ledger/trimmer to jiffy hang the remaining 7x2 floor joists (supported on a load-bearing wall at the other end). These will be heavily nogged and it all makes sense - EXCEPT:

Take a look at the pics: Would you fix into those bricks? The 6.2meter span is 50% window (wood lintels) and the proximity (of only 2 brick courses) to the wall plate alarms me. Masonry joist hangers could be used but we'd never get it level: the mortar line is like the M6!

We could add steel (beneath purlin dwarf wall) and tap into it but trying to avoid that. Am I being paranoid here? I've NEVER seen trimmers that close to the edge. Yes Yes: I know: get a Structural Engineer out and lah-di-dah: just wanted to gauge response here.
Any thoughts/suggestions welcome.

 

[tony1851]

If the brickwork is unsound, there's no point in try to fix anything structural to it.

Normal method for a dropped loft floor is to use a steel beam with timber bolted to the web, and joist hangers off that.
But on a 6.2m span, you'd need a reasonably-sized beam.

On a separate note: how are the rafters to be restrained from spreading? The inspector might raise that question.

 

[c0wb0y]

Good point about rafter spread: the Purlins (Doubled 9x3s) will be propped by a dwarf wall resting on a steel beam spanning the entire width of house (rested on padstones on gable/party wall sides). That’s the plan atleast. Lots of timber on site so I’ve asked for the rafters to be nogged - can’t hurt and will assist with PIR insulation fitting. Architect spec’d 6x2 for rafters: we’re using 7x2s with fibre cement slates.

 

[c0wb0y]

I may have answered my own Q: if there’s steel beneath purlins, I could just web off that for suspended floor... DOH..!!