New door through cavity wall

I am planning on moving the bathroom from downstairs to upstairs. Part of this will entail putting a new door through what used to be an outside wall but is now internal due to an extension. The wall is a double brick cavity wall supporting ceiling joist above. The door will be a standard 6'6 2'6 size. I know I need to fit a lintel above. Could someone please talk me through the job in as much detail as possible - from scratch.....soryy if this is a pain. DIYISFREE posted a great post back in 2006 but not sure if he/she still gets on here
Thanks

you will need to fit a p.c.c. builders lintel to each leaf of masonry.

it is unlikely you will need any propping, but collateral damage may need making good above the lintels.

a standard 2' 6" door casing requires a brickwork opening size of around 32".

fit the lintels then remove the masonry below.

apply mortar to the top edge of the lintel and offer it into place. press it home up to the masonry then pack with slate/tile at the bearing point. or, if you have an acro handy wind the lintel up, squashing the mortar out, then fill with mortar at the bearings and allow to set. remove the acros later.
we tend to stitch drill along pre-marked plumb lines delineating the intended opening. we also stitch drill the lintel inserts too.

the more drilling you do the less damage will occur when you start hammer and bolstering.

the latest way i fix the casings is a little fussy but pays dividends. i remove enough width of masonry as to allow me to dab some plasterboard to the 'rough' exposed masonry tapping the plasterboard true plumb and square. once set this affords you a very good surface to fix the casing to. it can be pulled up tight to the pasteboard without the need for tricky packing. fix the hinge side tight then fix the latch side using uniform sized packers to suit.

when you fix the casing allow at least 5mm width oversize when packing. you can allow more if you wish.

once plastered in the casing will push in a little due to water swell etc.

if you get this part right it can mean little planing when fitting the door later on. even if the gap is oversize you can loosen a fixing screw and ease the casing in a little then pack.

any small gaps between casing and plaster will be dealt with by the architrave or quadrant.

thanks for that noseall......you said a 32" wide hole for a 2'6" door.....that would only give 1" each side for the casing.
What size lintel would I need to use?
Thanks again

the rebated part of a planed casing or door liner turns out at quite a bit less than 1"

32" will give a packing tolerance of around 10mm.

as i have said previous you can go wider with the masonry then dab a plasterboard lining to the aperture bringing it down to 32".

a pair of 1200mm x 100mm x 75mm p.c.c. lintels normally does the trick.

they can be cut with a grinder if necessary.

Cheers matey

Barkeep,

I still pop on to have a look every now and then. Works prevents me getting on as much these days.

Looks like Noseall has sorted you out.

Good luck mate.