New window board levelled over old one. Plastering questions

[brid]

On advice of my plasterer coming in later this week we have chiselled out the front of our old window board which is installed into a 'notch' at the bottom of the reveal. We have been told to leave the old board, which will be plastered into the walls which are all being skimmed and the window reveals re-beaded and skimmed etc.

So, the old board is not fully level, and the new board I've cut is perfectly level once i add a slice of hardboard under the right hand side of the newly fitted board to prop it up.

So, given that the plasterer is coming in to plaster up to the level of the new board, should i fill the 'gap' betwen the old board and the new board with a load of 'no nails' which I'm using to glue the new board to the old board (with hardboard wedge) before countersinking some screws to secure everything so we have no wet plaster getting into that gap and potentially wetting the mdf. I've sealed the underside and sides of the new MDF window board with PVA.

I'm a complete novice here!

 

[pinenot]

Let me get this straight, the old window board! is that the cill that forms the bottom of the window internal trim? and when you say you've cut of the front with a chisel, are you describing cutting back the protruding section of said cill to be flush with the wall?? ...pinenot

 

[foxhole]

I would not take carpentry advice from a plasterer.

 

[brid]

Let me get this straight, the old window board! is that the cill that forms the bottom of the window internal trim? and when you say you've cut of the front with a chisel, are you describing cutting back the protruding section of said cill to be flush with the wall?? ...pinenot

Yep, the plasterer advised me to cut back the old board (interior window 'sill') by chiselling off the front and to sit a new board on top of it, leaving the old board to be plastered back into the wall. His advice was to leave the old board there as the removal of it would be a nightmare.

The old board was not straight, and the new board i've sat on top is 90% straight (using no nails and hardboard wedges, and then screws) but i'm not happy with it.

.... I've since bought mortar, nails, oak window board and everything i need to just remove the old board and put a new one in. I doubt I'd ever be happy knowing the job was done the first way.

You live and you learn.

 

[pinenot]

Good! plasterers are seldom good advisor's in matters of joinery works in my opinion...pinenot

 

[Deluks]

So, just getting this straight, you will fit the board after the plastering is done? (Best way IMO)

 

[brid]

Another slight change of plan

Had my dad look at it, with decades more experience than me, and after seeing my first attempt which was just about level, and more than solidly set, we agreed that it made no real point ripping the walls and board out, just go go all the way back through the process to level things again with mortar and potential brickwork fixes.

So... I've bought another length of window board, oak this time, and we are going to just fit this again over the old board, using some L shaped brackets and screws to secure it, along with some no nails.

The plasterer will just lay the new boards for the reveal (the old reveals were really uneven) and skim up to the newly overlaid board, and over the chiselled back old board.

 

[chirpychippy]

Confused!.com, I haven't got a clue what your trying to do, but if your installing oak prior to plastering then you need to completely cover it over as any plaster overspill will make the oak turn black which cannot be sanded out.