Windows cavity detail question

[Snfubar]

As part of a bathroom refit I am removing the window and boarding (apparently fitted by Bob the builder's less competent brother using all sorts of scrap material).

Question is (I haven't fully disassembled so bear with me) ...

The cavity appears to be fully open and the window (pvcu) appears to be screwed to a board bridging the gap [plus some 'interesting' packing/botching) - I think that the screws from the window frame are in line with the cavity (i.e. no direct fixing to brick available). I would like to reduce the depth of the ingoe boarding so that I can tile deeper and am looking for pointers on the best way to close the cavity and allow a fixing.

Two options that spring to mind:

1) Insert bricks to close cavity using DPC vertically to avoid bridging and fix window directly to that;

2) Fix plate over cavity (presumably with dpc around to avoid bridging) and fix to that ... I can fix lath so I can tile to it;

3) I saw a detail on the web where a timber fill had been used in place of the brick in option 1 ... unclear how it was fixed although I suspect a big hammer. There was no dpc shown which was slightly surprising.

Preferred option is one that allows me to minimise boarding back into the bathroom (i.e. 1 and 3).

Anyone got any better ideas; dire warnings of doom or advice on detailing?

Any help appreciated.

EDIT>
The detail noted in (3) above is at http://masonryjobs.net/design_tools/masonry_details/details/01_402_2D.php

 

[stuart45]

If you are removing the window, then you can refix it to the external skin.
Method 3 with timber in the cavity and no DPC is an American method in a State where there are no real damp problems. Return the inner reveal with blockwork and a vertical DPC.

 

[^woody^]

Fill the cavity at the reveal with expanding foam. A DPC would be optional

Then if you can't fix to the external skin, some frames come with plastic fixings which are fixed to the internal skin and run horizontal to slot into the frame.

If not make your own with some galvanized strap and screw these to the frame before placing it, and then fix them to the inner reveal blockwork. These are then plastered over

 

[Snfubar]

Thanks for that guys

The window has to go back pretty much in the same place due to a funny detail at the cill and head.

The idea re making straps seems logical and I wil have a look at that when I get the window out (may have to screw a timber plate to window first due to a width difference internally ... some classic detailing here )

With regard to the blocking up idea - take it this would be simply dropping (bedding) a dpc down the outer leaf and piecing in brickwork to close it and fixing to this once everything has cured (I have some epoxy mortar I can use to get it done and cured quick). I take it there is no real need to tie into the existing brick as there is no real load ?

 

[stuart45]

If you decide to block it, use a vertical DPC. One thermalite block should give you enough cuts if you use a saw. You don't really need to toothe out for tying in, but you could use a few cut nails in the bed joints.