# Forum Home Renovation Plastering  Converting 90mm cornice to squareset or shadowline?

## Master Splinter

I'm trying to get a handle on the work involved in taking out a standard 90mm cornice and reworking the join to either squareset or something like shadowline. (I'm trying to go for a more modern look!) 
Is this a viable idea, or would the amount of fiddly work involved in making good the area typically hidden by the cornice be getting close to a "it'd be less hassle to resheet the walls" benchmark?

----------


## Vernonv

It's probably one of those things that you won't know until after the cornice is off. But my bet is that it will be easier to re-sheet. 
The cornice may not come off cleanly and could tear the paper on the wall/ceiling. If it does come off without tearing the paper, there will probably be a fair bit of cleanup work to remove the left over cornice cement. 
The other thing you may encounter is an excessive gap between the wall and ceiling sheets which would make squareset more difficult (although not impossible). 
Having said that, I have a feeling that the shadowline stuff needs to be done from scratch anyway.

----------


## Rod Dyson

It is a tricky job and have done a few, where people have changed their mind after cornice had gone up. 
Never impossible but how difficult it would be would depend on how the sheets were hung in the first place.  
I would forget about shadow line (P50 angle), this does need to be set up right from the start.  
However square set is not out of the question. The cornice adhesive can be cleaned off with a bit of work and a sharp scraper. If the gap is more than 15mm cut strips of plasterboard and nail in place, then tape the join created on the walls and ceiling with paper tape, just the width of a 4" stripper.  
If the gap is only 15mm fill it with cornice adhesive. and scrape back when it sets. Don't leave it too long to scrape back. Then use a ps17 90 deg internal angle to create the square set. This is like an external angle but reversed to make an internal. So the metal bead covers 30mm down the wall and out from the ceiling reinforcing or covering most of the infill pieces that you would put in. In fact the wider the gap the easier it would be to cut in the strips. When you tape the join keep it narrow don't spread the plaster out form the corner wider than the 4" stripper. That will make all the following coats easier.  
Normally I don't like using this angle but for this purpose it is perfect as it will hide a lot of sins!! 
The angle can be trowelled out each side with a 4" for a first coat 6" for the 2nd and 8" for the topcoat.  
You will find this will give you a very clean finish,  
I would give the square set a go, it can be done well using the angles and is more labour intensive but a dam sight cheaper than re sheeting the walls and ceilings. If that is the look you are after.

----------


## Master Splinter

Thanks muchly - that angle sounds like it would make it a lot more robust and possibly easier than I was expecting!

----------

