Cracks in plaster

D

dahamster

Registered User
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32
Hi,

I'm in my house about six weeks now and have noticed alot of cracking in the plaster at the interface betwen the walls and the ceiling. I'm fairly certain that tape was used here but the cracks are unsightly and some are big enough . Is this normal in a new house?
 
Normal enough I'm afraid. Homebond will advise that you redecorate the house in its entirety after year one- after all drying out is complete. for your cracks I would recommend decorators acrylic caulk, used sparingly its very useful for hairline cracks like this.
 
This is because we use the english system of building/plastering.
This would never be tolerated on the continent where Engineers with ultrasound equipment are regularly brought in to check the plastering for air bubbles.
 
Ultrasound equipment for searching bubbles in the plaster? I'm baffled.
How would bubbles get into the plaster? And how long would it take to scan an appartment block (most continentals live in such houses) with ultasound?
 
Carpenter said:
Normal enough I'm afraid. Homebond will advise that you redecorate the house in its entirety after year one- after all drying out is complete. for your cracks I would recommend decorators acrylic caulk, used sparingly its very useful for hairline cracks like this.
Click to expand...

Handy Tip: Wetting a sponge (not too much) and wiping the caulk into the crack(s) makes for a much neater job and also manages to keep your hands from spreading the stuff where is doesn't belong if you manage to make a mess of it you can wipe away with the wet sponge and try again this method is also handy for filling gaps in skirting boards, dado rails and archetrave for a much better finished look.

Good Luck ;)
 
My own favourite is to wet your finger and run the caulk in, gives a seamless finish. I don't know how decorators survived before the advent of acrylic caulk.
 
Carpenter said:
My own favourite is to wet your finger and run the caulk in, gives a seamless finish. I don't know how decorators survived before the advent of acrylic caulk.
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That's the window installers silicone sealant trademark ;)
 
Silicon sealant is not the same as acrylic caulk.The latter can be overpainted for example. And decoraters caulk/acryl is not water proof, sealing the bath tub with it wouldn't make much sense.
Make sure you buy the right stuff!
 
heinbloed said:
Silicon sealant is not the same as acrylic caulk.The latter can be overpainted for example. And decoraters caulk/acryl is not water proof, sealing the bath tub with it wouldn't make much sense.
Make sure you buy the right stuff!
Click to expand...

That was just a joke between myself and Carpenter :confused: I didn't mean to refer Silicone would do the same trick you are correct in what you say.
 
Aha! But if you do want to use a product (similar to acrylic caulk) which can be smoothed with a wet finger or spatula and CAN be overpainted- then you need to use "Rito" sealant, it's silicone free and can be smoothed/ tooled with wet tools/ fingers and is the business for bedding in windows, sealing thresholds, pointing around frames etc. It's clean and easy to use and doesn't get everywhere like silicone.
 
off the topic but whats the normal boiler cycling time with just underfloor heating running. Mine is burning for 2 and a half minutes and off for between six and ten minutes with just ufh i haven't check with rads upstairs on as well.
 
DOBBER22 said:
That's the window installers silicone sealant trademark ;)
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i find dipping your finger in washing up liquid is better, keep it from sticking to your hand and is cleaner to get off
 
Touch Wood said:
This is because we use the english system of building/plastering.
This would never be tolerated on the continent where Engineers with ultrasound equipment are regularly brought in to check the plastering for air bubbles.
Click to expand...
On the continent they do not use the traditional wet plastering system, it is predominantly taping and jointing...I have lived and worked many years in Europe and have never heard of let alone seen anything so nonsensical as ultrasound equipment called in to check for air bubbles...I assume you are codding!!
 
Ultrasonic systems as well as X-rays are used in the concrete prefab industry to check for air bubbles and steel positioning. When plastering a wall it is very unlikely that the plasterer works in air bubbles. These wouldn't cause cracking anyhow, it is the evaporating water that makes the plaster shrinking and -maybe-cracking. Thermal insulating plasterwork actually integrates air into the plaster. But this air would be bound to expanded polystyrene beads or perlite or a similar material (FBT-the poroton people- are selling this plaster, I used it myself), as I said- working air bubbles on their own into plaster is a difficult if not impossible job.
Cracking plaster is most likely caused by the undry and/or settling/cracking back struckture, the wall. And of course by mistakes and bad material choosen by the plasterer.
Wet plastering is widely done on the continent, the world's largest manufacturer of plastering pumps/machines (PUTZMEISTER, check the web) is a German company. I have seen their machines used here in Ireland as well.
 
When you plaster a wall if your technique is not correct you can fold air pockets into the plaster much the same as folding air into the mix when making ice-cream or making bread. Water evaporates and the plaster shrinks and the plaster often cracks at the weakest point where there is an air pocket. This was noticed in Finland when they were introducing a building quality assurance scheme 20 years ago.
Before a builder recieves his final payment in Finland he has to show the architect the engineers reports stating that there are no air bubbles in the plasterwork and a thermal image of the building showing correctly installed insulation.

A good friend has a medium size building company in Finland and we often discuss different building systems and techniques.
In Scandinavia 20 years ago they had a similar system to the present Irish system with good builders and bad builders, the bad builders were giving the good builders a bad name. The industry brought in a quality assurance scheme where every tradesman had to guarantee his/her own work for 10 years. Tradesmen started to demand higher quality building materials because sometimes the problem was with lower quality building materials.
If the plasterwork fails the ultrasound test in Finland the plasterer is obliged by law to redo that work.

If you want to become a builder in Scandinavia you have to go to college for 5 years first to learn about building.

Heinbloed- how eco friendly is the FBT/Perlite plaster and does it offgas much?
 
Heinbloed you are right with regards to the putzmeister, though much of its use is for external purposes, internally there is another machine called the G4 or since I last used one the new generation G5. The G5 is a one coat sprayed plaster. When I stated a traditional wet plastering system I was referring to the old hawk and trowell render and set method of plastering, when the Germans tend to use the Putzmeister internally it is usually left as a float finish without a plaster skim, there are skims available called red and gold band but they are very poor. The putzmeister is an excellt machine but it requires a certain grade of sand which in Ireland is very expensive so makes its use prohibitive.
Touchwood I can assure you that there is no way that a plasterer folds air into a render or skim gauge that later manifests itself in a crack, there are instances where air bubbles form but they are instantly apparent, but are unconnected to your claims, there are reasons for cracks appearing and there are ways to reduce them from showing, but folding in air pockets is absolute nonsense.
 
legs-akimbo said:
there are instances where air bubbles form,
but folding in air pockets is absolute nonsense.
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You admit that air bubbles form, so how do the air bubbles form then?
By the mixing process or by the process of applying the plaster to the wall. Or maybe you have a better explaination.
Why do they vibrate concrete?

Take it handy on the comments!!!
 
Theese are termed blebs touch wood and are the convex swellings on finished plaster work , it has a number of causes and they manifest themselves as tiny blisters on the finish plaster and are wholly visible and can be worked out of the finish as the plaster is polished to a finish. Vibrating masses of concrete can not be compared to a 12mm floating render coat or a 3mm skim. I have been a plasterer for twenty five years and can assure you that folding in air pockets does not happen my friend, certainly not with traditional wet plastering materials as used here at any rate.
 
Just to add the cause of blebbing is invariably in skim coats only and is usually caused by dusty backgrounds, to dry bonding coats or backing coats that have needed excessive wetting down prior to skimming due to their pourosity. It is never caused during the mixing process.
 
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