DIY Home Improvement, Remodeling & Repair Forum > DIY Home Improvement > Carpentry and Woodworking > "cupping" in prefab counter tops




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Old 02-14-2010, 01:28 PM  
Nestor_Kelebay
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Default "cupping" in prefab counter tops

I've noticed that the prefab counter tops sold by Home Depot (and others) here in Winnipeg have curvature to them which I don't notice in installed plastic laminate counter tops.

Specifically, the curvature that I'm referring to is the front-to-back curvature so that if you were to lay a straight edge from the front bullnose to the rear backsplash of the counter top, you'd see a gap between the straight edge and the counter top.

I've been told that this curvature is called "cupping".

I've also been told it's caused by:

1. the plastic laminate shrinking as it cools, and
2. the particle board swelling as it absorbs moisture from the air.

Does anyone know of a web site or other source that would establish with certainty what this curvature is called and what causes it?



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Old 02-15-2010, 02:05 PM  
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if its what I'm thinking of its part of the design. Its done that way so that you contain a spill (somewhat) to the counter. Its part of the design and not a defect (if its what i'm thinking about)

The technique is called postform - essentially the laminate follows from the front edge, around the bull nose, and up the backsplash.



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Old 02-15-2010, 09:18 PM  
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No. I fully understand that the concept behind the design in the picture is to contain a liquid spill.

I'm talking about the UNINTENTIONAL curvature of the counter top from front to back. That curvature forms in the counter top after it's manufactured, and is not part of the design of the counter top. If you put a straight edge, like a spirit level, on the counter top and perpendicular to the back splash, you'll find a gap from 1/16 inch to over 1/8 inch between the top and the spirit level.

The difficulty this creates in installing counter tops is that if you have an "L" shaped counter top, then the "cupping" of both tops has to be identical to get them to meet properly in the mitered corner. If one top is flat, and the other cupped, then you simply can't get the tops to meet well in the corner. I've come across this so many times, that now I spend an hour at the home center every time I buy a pair of counter tops trying to find the flattest ones.

Maybe go look at a prefab counter top at Home Depot or Lowes, and you'll see what I mean.

Thanks anyhow for trying to help.

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Old 02-16-2010, 06:27 AM  
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It comes down to..they are junk. The board material is junk, and the laminate they cover it with is very thin...and junk.
The combination of the way it is heated to get the formica on, then cooled and the moisture in the building does it, and it will not go back to original.
Those companies play the #s game, they sell it and most times it will not come back...yet folks still go there.

Can you tell I'm biased? But that comes from professional experience...if they did a good job , contractors would only shop there.
The #s on diy are much greater , with less of an expectation level.

Just worth.

Make your own top...or contact a post form company.

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Old 02-16-2010, 11:13 AM  
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Default Cupping

Cupping in laminate countertops is almost always caused by laminating only the top surface of the particle board. A good quality c-top should always be sealed on the bottom side with another type of laminate called backer, which is a very thin layer of resin impregnated paper. In woodworking they say whatever you do to the face should be also done on the back in order to seal out moisture, which is what will cause cupping. Usually only pro c-top manufacturers, or custom cabinet shops will do this. If you are thinking of installing a cheaper "cupped" c-top, you should be okay as long as it is properly glued down. Most installers will use Liquid Nails or any other kind of construction adhesehive.

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Old 02-16-2010, 12:41 PM  
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Thank you so very much for your personal opinion, InspectorD.

But what I need is not so much an opinion, but a reliable source of information to tell me what this kind of warping is called and a knowledgeable explanation for what causes it?

You see, a former tenant scorched on of my plastic laminate counter tops, and I really don't want to go before a hearing of the Residential Tenancies Commission and say "My laminate counter tops are junk. The particle board core is junk and the laminate glued to it is garbage. But, I still want to put a real big dent in my former tenant's damage deposit for scorching that worthless crap."

Thanks for your opinion, but I remain...
looking for a source of information that can tell me what this kind of warpage is called and what causes it.

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Old 02-16-2010, 12:59 PM  
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That warping is caused by only laminating the face or top surface of the particleboard. A quality c-top will have both sides laminated in order to seal the bottom from moisture. The bottom is almost always laminated with a very thin resin coated paper known as backer.

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Old 02-17-2010, 03:11 PM  
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Finishguy:

I suspect the warping is the result of what you say. Since the laminate will prevent moisture from being absorbed into one side, but not the other, then the top will bend concave upward as it absorbs moisture. And, of course, the longer it's exposed to the atmosphere and the more it absorbs, the greater the warping.

But, I'm going to be arguing my case in front of 3 people who consider that I don't know anything since I'm not an "expert" on the subject. What I really need is to find a web site or some other authoritative source of information that will confirm what you (and InspectorD said). I'm having no end of trouble finding anything about warped particle board plastic laminate counter tops on the internet.

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Old 02-17-2010, 08:36 PM  
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Default well

nestor, I know I get he77 for this sometimes,..but did you contact the company and ask them?
Cupping is a fact of wood...and any wood product. The moisture moves inside the cellulose material ...always. I have worked in many cabinet shops, and when we delivered tops from the shop to the site...they moved by the time they got installed if they where not sealed.
I do not know of a source to look at.
These guys do it right...call them.http://www.vtindustries.com/images/news/3.pdf

I'm sure they will tear up the competition, and help answer your question.

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Old 02-17-2010, 08:57 PM  
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[QUOTE=Nestor_Kelebay;40953]


You see, a former tenant scorched on of my plastic laminate counter tops, and I really don't want to go before a hearing of the Residential Tenancies Commission and say "My laminate counter tops are junk. The particle board core is junk and the laminate glued to it is garbage. But, I still want to put a real big dent in my former tenant's damage deposit for scorching that worthless crap."

QUOTE]

Nestor, what is the tenats arguement for his damaging your counter top? If he broke it why won't he fix it?



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