ceiling cornice cracks

joe-90 · Posted: Sat Feb 25, 2012 12:12 pm

I don't fit coving if I can help it. I can also plaster - so I don't have wonky walls. I won't fit coving to wonky walls. It looks pretty naff if you do. So I use caulk to give that final seal between wall and coving. Never had a problem. If you are trying to fill several cm with caulk - then of course it will crack - but it's a bodge job anyway.

RMS · Posted: Sat Feb 25, 2012 1:46 pm

joe-90 wrote:

I can also plaster - so I don't have wonky walls. I won't fit coving to wonky walls..

Depends what one would deem as 'wonky'.

I can also plaster and am very impressed if you can achieve a perfectly true and flat finish on walls and ceilings. Are we talking (0mm) tolerance over the whole room. I would love to check out a newly plastered room including the ceiling carried out by yourself with my trusty straight edge.

joe-90 wrote:

So I use caulk to give that final seal between wall and coving.

Really, surely this would be pointless if you can achieve a 'perfectly' true/flat finish, or am I missing something here?

joe-90 wrote:

I don't have wonky walls.

joe-90 wrote:

Never had a problem. If you are trying to fill several cm with caulk - then of course it will crack - but it's a bodge job anyway.

Fitting coving in a room and filling the top and bottom with caulk instead of using the adhesive as per the manufacturers instructions is a bodge job. Why would you use a 'flexible' caulk anyway,

as

joe-90 wrote:

If the coving moves then it was never fitted correctly. Where does the movement come from? Where is the movement going?

The reason cracking may occur was explained:

RMS wrote:

I find that water based paints will usually show lots of cracks when applied to caulk unless you apply an undercoat before. You will not have this problem if you use the coving adhesive to fill any gaps.

TheDec · Posted: Sat Feb 25, 2012 4:58 pm

Sometimes, and I mean sometimes, when a water based paint system is applied over caulk, the system can often separate, this is a phenomina known as cissing, yet it is often confused with crazing, cissing is when the paint fails to bond to itself and crazing is when the system fails to bond with the underlying substrate.

When this phenomina comes into play regarding the the application of water based paints over caulk, a thinned oil based undercoat should be applied prior to any further water based paints.

Dec

joe-90 · Posted: Sat Feb 25, 2012 5:05 pm

RMS wrote:

joe-90 wrote:

I can also plaster - so I don't have wonky walls. I won't fit coving to wonky walls..

Depends what one would deem as 'wonky'.

I can also plaster and am very impressed if you can achieve a perfectly true and flat finish on walls and ceilings. Are we talking (0mm) tolerance over the whole room. I would love to check out a newly plastered room including the ceiling carried out by yourself with my trusty straight edge.

joe-90 wrote:

So I use caulk to give that final seal between wall and coving.

Really, surely this would be pointless if you can achieve a 'perfectly' true/flat finish, or am I missing something here?

joe-90 wrote:

I don't have wonky walls.

joe-90 wrote:

Never had a problem. If you are trying to fill several cm with caulk - then of course it will crack - but it's a bodge job anyway.

Fitting coving in a room and filling the top and bottom with caulk instead of using the adhesive as per the manufacturers instructions is a bodge job. Why would you use a 'flexible' caulk anyway,

as

joe-90 wrote:

If the coving moves then it was never fitted correctly. Where does the movement come from? Where is the movement going?

The reason cracking may occur was explained:

RMS wrote:

I find that water based paints will usually show lots of cracks when applied to caulk unless you apply an undercoat before. You will not have this problem if you use the coving adhesive to fill any gaps.

I'm a darby fan (Not Cloughies team). I work to tolerances of about a mm. If you can't do that too - then you are no plasterer. You stick to bodging it with coving adhesive.

vibrobullit407 · Posted: Sat Feb 25, 2012 6:21 pm

I think we have wondered off the topic slightly into fitting new coving. In this instance then using the cove adhesive to fill would be the best option in my view. With regards to the OP with an existing period coving cracking at the edge then caulk would be my proffered choice.

I also have to admit that I find it hard to believe that plasterers work to a tolerance on a whole wall of 1mm. Maybe a 3mm per 1m2 would be more believable but I am no spread. No body is perfect and to say that a tolerance of 1mm over whole walls is bordering on perfection in my eyes!

RMS · Posted: Sat Feb 25, 2012 6:24 pm

joe-90 wrote:

I work to tolerances of about a mm.

1 mm

So Mr Joiner can chuck his plane away and forget scribing his kitchen work top into your walls then! hats off to you!

Who needs a plumb line when papering one of your plsatered rooms. Just use the internal edge as a straight edge. Whats the worst it's going to be out 1mm

joe-90 wrote:

You stick to bodging it with coving adhesive

You naughty boy

What you fail to realise is that when you apply the cove adhesive (or do you stick it up with caulk?) you will naturally have a small gap top and bottom as when you press the coving into the wall and ceiling the adhesive does not compress to nothing.

Some of the adhesive will naturally force it's ways out and you can remove the excess and use a sponge to smooth the rest it in. The excess can be re-applied in any gaps where the adhesive has failed to come through and any parts when there are slight (or in your case 1mm) gaps.

To use caulk around the full room is madness and probably explains why:

joe-90 wrote:

I don't fit coving if I can help it.

joe-90 · Posted: Sat Feb 25, 2012 6:30 pm

It looks sh*t so very 80s. I take more down than I put up.

TheDec · Posted: Sat Feb 25, 2012 6:48 pm

Well, they would advise that would'nt they. Yet a pro dec may both have a far better method and cure tucked up his sleeve.

Dec

TheDec · Posted: Sat Feb 25, 2012 6:50 pm

Apoligies joe, my reply was not aimed at you.

Dec

RMS · Posted: Sat Feb 25, 2012 6:53 pm

TheDec wrote:

Well, they would advise that would'nt they.

who is 'they'? and advise what?

TheDec wrote:

Yet a pro dec may both have a far better method and cure tucked up his sleeve.

Dec

such as?

TheDec · Posted: Sat Feb 25, 2012 6:59 pm

Are you a pro dec or a sparks, if the former you would already know the answer, would you not.

Dec

RMS · Posted: Sat Feb 25, 2012 7:05 pm

I don't even know what you are referring to dec.

Surely this answer you are hiding, If relevant would have been mentioned by now would it not?

RMS · Posted: Sat Feb 25, 2012 7:07 pm

Would you care to share your thoughts on how you would fill the gaps top and bottom of coving when installing?

vibrobullit407 · Posted: Sat Feb 25, 2012 7:13 pm

TheDec wrote:

Yet a pro dec may both have a far better method and cure tucked up his sleeve.

Dec

Could you please elaborate for the OP's convenience as I'm sure it will be beneficial to his/hers problem and for my own future understanding!

TheDec · Posted: Sat Feb 25, 2012 7:13 pm

NO

In this instance, I ask again are you a Decorator or a sparks!!!!!!!!!!!!!!!!!

Dec[/b]