Rotten Window Beam

Hello,

I recently bought a house and have started to renovate. Whilst taking the wallpaper off along can some of the plaster, exposing some of the lath.

I decided to remove the lath and board, however once I got more plaster off I could see that the beam is rotten.

Can someone tell me if this is a simple job to replace? Can this be done by a DIYer?

Please see attached pics.

Many thanks,
Rob

could you post pics of the outside of the window frame showing the wall context, and details of any cracks or bulges in the render?
and pics of the floor/joists in the room/loft just above the window?
are your upper floor joists running into the window wall or running parallel with it?
is that a solid wall or is there a cavity?
whats the total thickness of the wall?

the window frame seems to be set flush with the outside surface - this wrong. it should be set back in the reveal by a min of 75mm from the face of the wall.
the Pvc frame is supporting a course of soldier bricks. this wrong too.
there should be a lintel supporting the outer brickwork and a lintel support for the inside brickwork, sometimes its the same lintel - the load should not rest on the frame.
your Pvc frame is a replacement frame for an old double hung wooden box frame. box frames were very strong.


it might be you have to strip the plaster from the reveals and well above the window head. cut the plaster with a knife just below the coving,this will break the bond of paint and plaster.
and take care not to disturb the plaster coving when removing plaster just below it.

You may need a concrete lintel, pics from outside would help

Blup

Pic attached of the outside. Forgot to mention it's an upstairs window.

I've added a pic of the external and there appears to be no issues with no cracks etc.

Wall thickness is 250mm from the inside of the external brick.
Solid wall with no cavity.

Unfortunately I can't get to the joist above as the room above has been closed off as in the additional pic.

Many thanks,
Rob

maybe its just me:
1. will you point out where the frame in question is located in the second lot of external pics?
2. neither can i see that wall only being 250mm thick?

from the outside all the frames in view are well set-back?

better resolution of your pics now shows further internal cracks to the left of the window.

i dont see where the joists tails of the loft floor joists are sitting above the perished lintel?

anyway, you would have to prop the loft floor joists about 1m back from the wall - to give working space. then build a short stud wall or use two Acrow props and plates to support the upper floor while you install a new lintel.
remove the damaged lintel and the surrounding plaster,
and then post pics of the cleared area.

be alert for falling bricks or debris.
dont go into the loft until all is safe below.

It’s the one closest, with the window open. 250mm does not include external reveal.

Would I just replace like for like? Or would you suggest something else?

Cheers

as i suggested above you will have to clear and photo the cleared area before any next move.

it might be worthwhile to investigate the condition of other opening lintels in the house?

Consider replacing that flimsy window with a proper timber double glazed sash as well. Not only will it do a better job and not look sh1te, but it will improve the value of your house