Very worried about quality / safety of window company building work - please help!

thearchitect

None of that work is particularly clever and I apologise for saying so on an MSE thread but my advice is that you speak to a local structural engineer as a matter of urgency and certainly before you make any more payments to the contractor.

The clear bearing of any lintel should be a minimum of 100mm - architects and engineers usually specify 150mm to give them a margin of error.   The load from each end should be spread evenly on to sound masonry, which can be done using a padstone, and it is essential that the bearing be packed tightly using a non-compressible material.  Stell is not normally used because it is ferrous and will, over time, corrode.

Steel shims should certainly not be used on the outer leaf for similar reason.   In modern buildings tightly tamped and filled mortar is used, whilst traditionally (and still in conservation work) slate pinnings are placed. 

Yes, steel lintels are usually galvanised and/or have a PPC in situ.   Stainless steel lintels are to be preferred but do bear in mind that some grades of stainless will show light surface patination similar to rust.   In any event here should be a dpc or cavity train in-situ to the upper face.

On a final note, even with a central pier to be fitted that lintel looks light.  A structural engineer should have done a calculation to ensure that it is fine.

FreeBear

thearchitect said: In any event here should be a dpc or cavity train in-situ to the upper face.

I think you mean cavity tray ?

In any event, the OP has solid 9" brick walls, so no space to install a cavity tray as such.

thearchitect

Dashed autocorrect, yes cavity tray.  Not required in a solid wall, of course - my mistake.

stuart45

It'll be interesting to hear what Building Control have to say about this job.