Laminate Countertop Substrate

[Lustreking]

I'm finally getting ready to make countertops for my kitchen. Is there any disadvantage of using MDF instead of particle board for the substrate? Should I paint or otherwise seal the underside?

Thanks,
Steve

[frumper64]

I'm not sure about particle board, but if I were going to use MDF I would be sure to seal it really well. It doesn't do very well with moisture.

[mschrank]

Either PB or MDF can be used. MDF swells and disintegrates when exposed to moisture, and so does PB.

If you want to do it right, you should apply a "backer" sheet of laminate to the underside. It's just like the laminate on the top, but without the color/design and is cheaper.

[cabinetman]

As its been said both MDF and PB can be used. Sealing or laminating the back adds some degree of protection. Over the dishwasher, and around the sink, plywood should be used. Whichever materials you choose, 3/4" works best for countertops.

Laminate for countertops (horizontal grade) is usually 1/16" thick. Vertical grade laminate is usually 1/32" thick, sometimes called "V32". Most brands have the same selections for many colors and patterns, for the two thicknesses. Laminate considered "backing" is usually thinner than vertical grade and comes in around 1/40" or so. Thickness for backers varies among manufacturers.
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[LarryG]

The best material for countertop substrates is industrial-grade particleboard complying with ANSI A161.2, Grade M-2. This is a heavy, dense material far different from the ordinary "flakeboard" that is commonly used for underlayment or prefinished shelving; ie, what most people visualize then someone says "particleboard." It is virtually all we will accept on our projects.

I think MDF will technically meet the ANSI specs for countertops, but I personally would never use it in a kitchen. It's too soft, and has far less moisture resistance than M-2 particleboard.

Although you didn't ask about plywood, it too should be avoided. Of the three materials, plywood is the most prone to warping and cracking; it often has inner voids that compromise its strength and/or can eventually telegraph through the laminate; and it is particularly prone to delamination around sink cutouts. Every now and then on one of our jobs we'll get some jack who wants to cut corners and use plywood countertops. Our answer is always, "No way."

Whichever material you use, sealing the edges well -- around cutouts, and at the back and ends where moisture can wick down from the backsplash -- is imperative. As mschrank mentions, a backer sheet of liner-grade laminate is recommended if you want the best possible job.

[cabinetman]

There are on this forum many members who are actively doing woodwork, furniture and cabinetry for a living. There are others who enjoy this craft as a hobby or an occasional activity making gifts or DIY stuff.

I have deep respect for those that are involved to whatever extent they choose. Anyone can sign up here and type anything they please. For some of those posts/replies the information is based on direct knowledge. Others are from things heard or "someone somewhere said" sources. And then there are responses that are conjured up from sources on the internet and relayed as personal experience and intended to be factual, and be the "the last word" on the subject.

There are posts some make that come after a post that have tidbits of info that may or may not be relevant or true, and extraneous to say the least, but intended to be that intrinsic knowledge substantiating an "experts" reply. Be it known, even those that do the work offer their "opinion", which may be an "opinion" from other sources which may include internet sources, something they read somewhere, something some shop did, a TV show, or books, periodicals, etc. Whatever the source is represents an opinion. Fortunately posts and replies get subjected to several thousand sources (our members) for their "opinion".

Problems one may incur from a certain procedure or material are sometimes substantiated by the inexperienced or ill informed by citing possibilities to make it sound believable. I don't want to call anyone names for what they want to use for their work. There are definite reasons for the use of one material over another, and most of those reasons are outlined by the AWI (Architectural Woodwork Institute), in their "Quality Standards". For those that actually don't do the commercial and residential fabrication and installation, it's understandable how easily they can be misinformed.
.

[LarryG]

There are on this forum many members who are actively doing woodwork, furniture and cabinetry for a living. There are others who enjoy this craft as a hobby or an occasional activity making gifts or DIY stuff.

I have deep respect for those that are involved to whatever extent they choose. Anyone can sign up here and type anything they please. For some of those posts/replies the information is based on direct knowledge. Others are from things heard or "someone somewhere said" sources. And then there are responses that are conjured up from sources on the internet and relayed as personal experience and intended to be factual, and be the "the last word" on the subject.

There are posts some make that come after a post that have tidbits of info that may or may not be relevant or true, and extraneous to say the least, but intended to be that intrinsic knowledge substantiating an "experts" reply. Be it known, even those that do the work offer their "opinion", which may be an "opinion" from other sources which may include internet sources, something they read somewhere, something some shop did, a TV show, or books, periodicals, etc. Whatever the source is represents an opinion. Fortunately posts and replies get subjected to several thousand sources (our members) for their "opinion".

Problems one may incur from a certain procedure or material are sometimes substantiated by the inexperienced or ill informed by citing possibilities to make it sound believable. I don't want to call anyone names for what they want to use for their work. There are definite reasons for the use of one material over another, and most of those reasons are outlined by the AWI (Architectural Woodwork Institute), in their "Quality Standards". For those that actually don't do the commercial and residential fabrication and installation, it's understandable how easily they can be misinformed.
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QFT.

Unbelievable.

Basically what you're saying is: "There are lots of opinions, but mine is the only one that matters." Nice.

Your desperate need for approval is well documented, "cabinetman," as is your customary treatment of those who disagree with you. But this is over the top even by your standards.

I may have more to say on this later, but right now I'm basically speechless.

[Hellrazor]

This is going to be interesting...

Cabinetman, do not turn this into head swelling BS festival. 3 paragraphs of ego stroking is a bit over the top.

Steve, make sure you seal whatever product you decide to use. Steam from a DW and water from the sink can cause some major issues otherwise.