Now I have got your attention . I have attached 3 photos of some cornicing that was put up in our kitchin by Harvey Norman 3 months ago when they put in a new kitchen. It appears the nail(s) are moving out and have caused the local plaster to break.

As well as this, a crack has formed on one of the joints and it moving away from the plasterboard.

Can this happen in such a small space of time or is it just bad workmanship?.

All replies will be much appreciated.

Cheers
MH

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Looks like the cupboards are moving or shrinking a bit.

Al

Hi Metal head.

What you have there is not uncommon around a kitchen cupboard.

The has been some obvious movement in the cupboards to cause the type of damage around the nail.

It appears to me that whoever installed the cornice has done the correct thing by nailing/screwing as well as the cornice adhesive. Movement in the cupboard bulkhead is the cause of the cracking, I would address this before an effective repair can be done. Without seeing the structure it is hard to recommend a way to fix the bulkhead.

There can be other causes such as flex in a truss roof or floor movement if its a 2 storey home, etc. When you repair the cornice use a flexible sealant to the under side of the cornice where is abutts the timber bulkhead.

Plaster will not adhere to the MDF bulkhead and will form a hairline crack underneath. (this is only a part of the problem you have here).

I use a different method of cornicing around a cupboard bulkhead that does not require screws or nails, that allows for slight movement in the cupboards.

The main objective is to attach the cornice in such a way that it won't fall down and allows for very slight movement in the cupboards. When you fix with a nail or screw and there is movement the nail or screw will always pop or in the worst case break away the cornice underneath as you have there.

By fixing the cornice the way shown in the pic (rushed drawing) you have no nails to pop and very solid fixing, that also helps keep the bulkhead solid. You also need to use cornice adhesive on the edge of the mitres to lock them together, rather than just filling the gap.

Hmm it won't let me attach the pic comes up with error on page. I will post this, then put the pic in another post below

Cheers Rod

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Here is the pic I hope. In addition to the above information. If you cant put a temporary nail in due to damge to a pre-finished bulk head, use screws through the cornice but remove them after the cornice cement has set. Then patch where the screw holes were.

Leaving the screws in, can lead to the problem Metal head has.

Caution though:
Only remove the screws if you have applied adhesive as described in the pic. If you use the standard method of applying adhesive, you will need to leave the screw in place.

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Only 3 months I would be contacting Harvey Norman what ever the cause

As it turned out Harvey Norman did sent a plasterer out to rectify the problem(s) but said it was highly likely to happen again if there was further ground movement which should it happen again they would not responsible for - fair enough.

Well since then we have had further movement and we got the reblocker in again - via the building commission - a month ago. Although a couple of the cornice repairs did breakdown again during the past year, a couple more have "exploded" since the relevelling by the reblocker. Thus I am going to repair them with Gyprock's multi-purpose joint compound, is this OK for this application?

I will do has Rod suggested and leave the screws out (unlike Harvey Norman's plasterer did). Given that it appears to be solid elsewhere I think this should be OK!!.

I have also got an hair line crack (straight) but it doesn't appear to be where a joint is, will the above mentioned compound be OK to use for this? If so, do I just push it into the joint, or just overlapping and I have to sand it back later?

I plan on using "No More Gaps" for the gaps between the cornice and the bulkhead as rod mentioned given that there maybe yet more movement.

Cheers
MH

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Cornice cement will be easier to shape in this case. It is a nasty type of situation as it is a weak point and is liable to form a hairline crack arround the patch some time in the future. I would actually put another screw in either side of the patch to prevent local movement that could cause the hairline crack as previouly mentioned. If you get further structual movement nothing will stop it.

The multipurpose is great for detailing decorative cornice if you are looking for a perfect job! I used it on my own house to take out every little pin hole, chip etc that is common in all decorative cornice. The reason - I could walk around on my stilts and touch up every spot in the entire house without having to stop and mix up. It is not good for large holes etc as it shrinks and requires sanding. By the time I had done the lot I went around with some very fine sandpaper and tidied up.

Many situations in plastering can be dealt with with a wide range of materials, that will all do the job one way or another. The difference is the quality of the outcome and the speed and effort required to bring it up to the desired quality. Its horses for courses, but it requires many years of experience to really know what works well, where. Blimey I employ plastering gangs that have know idea of simple techniques to make a job better and easier.

I have spent my working life as a plaster experimenting with materials and methods with one goal in mind, to get the best possible outcome in the shortest time possible, without compromising the quality of the finished product. Ok waffle off. Good luck with it.

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You can waffle on as long as you want Rod, as like many here I appreciate the time you spend passing on your advice given your busy lifestyle.

Cheers
Metal Head

I'm with him. Great posts, Rod, thanks for being there for us amateurs, we all appreciate the time and effort.

Thanks Guys.

I appreciate your comments.

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Yes Rod I agree, thanks for the input. And the website is great