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Corian worktop bowed (update. Kind of)

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mindthatwhatouch

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Hi,
Want to pick the collective and knowledgeable brains here.

Corian work top fitted to our kitchen island for approx 3months before a noticeable bow appeared. Approx 5mm drop over 900mm. There are metal support bars in there for the overhang.
The manufacturer and installer has removed for repair. I presume into their oven and/or press.

My concern is when it comes back what’s to stop it happening in say 5 years time.
Any thoughts?
 

Distinterior

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How much is the overhang..?
How big are the metal reinforcement bars..?
What is the apparent thickness of the worktop..?
Are there any appliances within the Island that produce heat..?

There are many factors that can affect the Corian.....Maximum unsupported overhang for 12mm Corian is 300mm.
 

Lons

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I'd pose the question to the installer and ask for a written guarantee for an extended period of time.
Corian and similar products will deform if not properly supported and Corian in particular is only 12mm thick with an extra piece glued around the edge to thicken and give scope for detail. I'd suggest that whatever metal supports they've installed aren't up to the job and need beefing up, perhaps that's what they are doing anyway. Did the installer fit the metal support? It would normally be glued to the underside just as they do normally using MDF.
Without knowing details of your installation I would be surprised if your worktop was being sent back to the factory as it would possibly be cheaper to fabricate a replacement.

DuPont are a reputable manufacturer and if you have worries it might be worth contacting their technical department for advice though you need to be careful possibly at this stage not to alienate your installer.
 

Distinterior

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Here is a picture of the underside of a kitchen island worktop that I fabricated a couple of years back.
The finished worktop had the appearance of being 50mm thick and was Corian "Lava Rock".
2 of us really struggled to pick it up when it was finished.....it weighed a lot!

As you can see from the picture, there is a lot of support needed to reinforce the worktop, especially if the worktop is not supported completely by the cabinets beneath. This worktop had an L shape seating area at one end, so hence the need for the full length 50mm x 25mm rectangular Steel supports. The visible area underneath the overhang had a sheet of 6mm MDF inset into it to hide all the structure & support frame.

DSCN1057_zps15lyarcd.jpg


Here is a picture of the completed kitchen I fitted with the Corian worktop in position...

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mindthatwhatouch

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Distinterior":icqg9mpq said:
How much is the overhang..?
How big are the metal reinforcement bars..?
What is the apparent thickness of the worktop..?
Are there any appliances within the Island that produce heat..?

There are many factors that can affect the Corian.....Maximum unsupported overhang for 12mm Corian is 300mm.

Sorry no idea on size of metal bars. I think minimum 2 possibly 3, across the 900mm width. Obviously couldn’t see them as they’re covered by bottom layer of MDF.
32mm thick is worktop finished thickness.
No appliances at all in the island, or anywhere near it.
Overhang just under 300 mm. (From memory 280 but I can’t measure it cos it’s not here)
 

mindthatwhatouch

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Lons":39r3gsyk said:
I'd pose the question to the installer and ask for a written guarantee for an extended period of time.
Corian and similar products will deform if not properly supported and Corian in particular is only 12mm thick with an extra piece glued around the edge to thicken and give scope for detail. I'd suggest that whatever metal supports they've installed aren't up to the job and need beefing up, perhaps that's what they are doing anyway. Did the installer fit the metal support

Thanks for the reply, Yes supplied, manufactured and installed all by same company.
 

Distinterior

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It's difficult to tell from the picture but it looks as though its bowed at both ends...?

Is that colour " Sandalwood "? It certainly looks like it.
 

Lons

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mindthatwhatouch":2ekqd0mt said:
Lons":2ekqd0mt said:
I'd pose the question to the installer and ask for a written guarantee for an extended period of time.
Corian and similar products will deform if not properly supported and Corian in particular is only 12mm thick with an extra piece glued around the edge to thicken and give scope for detail. I'd suggest that whatever metal supports they've installed aren't up to the job and need beefing up, perhaps that's what they are doing anyway. Did the installer fit the metal support

Thanks for the reply, Yes supplied, manufactured and installed all by same company.

Hopefully the installers will put it right as that certainly isn't acceptable.

Are you sure you don't mean fabricated rather than manufactured? DuPont are the only manufacturer as far as I remember. You can get customer & technical help from CDUK in Leeds.

Just out of interest, I was clearing a shed only yesterday and moved a scrap bit of white with 20mm mdf still attached, it is maybe 150 wide x 900 long an no edge piece and it has a definite curve after standing for heaven knows how long against the shed wall so it's deformed under it's own weight in the same way timber would. Only good for pen blanks or drink mats now though I've weighed it down and at some stage will put some heat into it!
 

mindthatwhatouch

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Distinterior":xkumf1j9 said:
It's difficult to tell from the picture but it looks as though its bowed at both ends...?

Is that colour " Sandalwood "? It certainly looks like it.

Yes to both.
 

mindthatwhatouch

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Lons":3pyoz8xz said:
mindthatwhatouch":3pyoz8xz said:
Lons":3pyoz8xz said:
Did the installer fit the metal support

Thanks for the reply, Yes supplied, manufactured and installed all by same company.
Are you sure you don't mean fabricated rather than manufactured?
!

Yep sorry I should of put fabricated rather than manufactured.

I’m happy that they are going to flatten it, otherwise we won’t accept it when they return. The post was for curiosity on the cause, and our big concern is the thing staying flat, long term.
 

Distinterior

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It is likely they will either need to un - fabricate the worktop and somehow increase the the amount of metal support for the overhang.....or, what is more likely, they will need to fabricate the work top again from scratch.

Your existing worktop will not be able to be put in an oven and heated, hoping to straighten it up. Any heating that needs to be done to Corian HAS to be done before the worktop is glued in any way.
 

AJB Temple

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Do you have a refund option? If so then replace with quartz.

Du Pont's patent on Corian ran out years ago and there are numerous polymers around now but they are all heat sensitive and nowhere near as tough as quartz or granite. When I used to be in the property development business, Corian was more popular than it is now as the moulded sinks etc were an in thing. I could never see why people specified it given the drawbacks (it's thin, basically plastic), and needs a lot of support. These days it is not really any cheaper than engineered solid surfaces such as quartz, or quarried stone such as Granite (unless you are going super fancy).

Kitchen manufactures frequently skimp on support for work surfaces, as no one sees it, but is it very important. I am installing a 5.2 metre by 1.4 metre island in my own kitchen and that will be in quartz. The supplier (trade) would have me believe I can have a 300mm unsupported overhang if I want (I don't) but I would pay no regard to this claim.
 

marcros

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How much overhang do you think you would be comfortable with on quartz ajb?
 

AJB Temple

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For a breakfast bar (say) I prefer not to have the surface completely unsupported, even if the spec will allow say 300mm. You get people plonking children or even heavier beings on them (eg women), rather than just balancing a breakfast bowl and some glasses. When selling a property as a developer you cannot realistically sell with a list of "don't do this, that and the other" and it is cheaper to play safe at the outset and anticipate stupidity or carelessness, than deal with a warranty claim later. Replacing worksurfaces on a finished site is a right pain and takes up management time as well as site team time. Corian needs to be really well supported and in my experience with former clients is a poor choice for large overhangs unless you have built a really solid cantilever frame or some such. I well remember an issue with one client who had a moulded in sink and it distorted from her frequently pouring boiling water into it. You are not supposed to do that and it meant replacing the entire top.

The local bespoke maker where I live now will do 300mm unsupported on quartz (and whatever you like supported. In my own kitchen, build (by me) currently in progress, I will overhang the quartz by 30mm or maybe 40mm - I will decide when it is templated next week. This is all built on a very solid oak frame, all the bespoke internal divides are 25mm baltic birch ply, and the top sits on this and the rebated oak frame. The top on mine is 18mm ply and this will support the quartz top, which has to be in two pieces because of the size. Cuts for induction hob, tepinyaki and downdraft extractor are all supported from below.

I prefer quartz these days, especially if using 20mm for elegance, because it is so tough. Corian does not like hot pans, it does not like big temperature variations, it scratches easily and in my experience determined clients managed to stain it as well.
 

Lons

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mindthatwhatouch":1x186sl2 said:
Out of interest, what sort of tolerance would you expect on the worktop?
I couldn't answer that for a poorly supported overhang but would expect very little movement on a correctly installed worktop and haven't come across any in my travels that had deformed. Most of my installations were thicker, mainly Mistral at 25mm thick and no problems whatsoever, that includes my own kitchen and utility room installed a number of years ago. I also at the time made a matching oak framed table with a Mistral top of around 1800 x 900 and that is as flat as the day I made it.

Despite reservation by other members I find that if the worktop is looked after just a you would with a quality timber top it lasts very well. Yes it can be scratched and will stain as will other materials, even granite can stain, but refurbishment and repair is pretty simple and unlike granite if someone knocks a big chip off a corner you can do an invisible mend for the cost of a pack of adhesive, I've had to do that for my daughter in law who's a bit clumsy but our own has only been re-polished once and that's 'cos I was bored.

Anyone who doesn't use a trivet for hot pans and cutting boards for prep shouldn't be spending £thousands on a kitchen anyway I'd suggest. :lol:
 

mindthatwhatouch

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Thanks Lons,

It’s been reinstalled after being remade, not what I would call flat. (hammer) (hammer) (hammer)
And the underside not as neat as the original, sealant in the join between the corian and MDF.

Looks like we’re back to the installer again.

Appreciate your advice.
 

Lons

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It might be worth asking Doc Bob to see if he's willing to comment. As a kitchen manufacturer any advice he's prepared to offer has to be worthwhile.
 

Distinterior

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If the finished thickness of the worktop is only 32mm, that doesn't leave much room for reinforcement. Having said that, if the total unsupported overhang is only about 280mm as you previously stated, I wouldn't have expected it to sag as much as your original pictures seem to indicate.

If the worktops have both been fabricated on an unlevel surface, the sag could have been built in...?
Once the edges and MDF have been glued, if the worktop wasnt flat from the beginning, ....

900mm deep and fully supported by 620mm? I wouldn't have expected much sag at all.
 

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