[cudink]

Is there an issue with using a full plywood subtop under a solid surface top?  Please let me know your thoughts.  Thanks!

[Lenny E]

1.) I would think there would be issues of expansion of the plywood with moisture. I would leave some room around the edges (1/8 inch) for the plywood to expand/contract with with humidity so it didn’t jamb up against  the built up edge or the back wall and end up warping /cupping and crack the top.. 

2.) Also I would attach the top using dabs of silicone or some other type non rigid adhesive.

3.) The other issue is heat. They don’t usually put full plywood or MDF underlayment under tops. They leave a frame around the edges about 4-5 inches wide and also put that across the edges of the cabinetry  (front , back and sides where adjacent cabinets meet) to support the top so the area over the cabinet interior is open. This helps dissipate heat into the cabinet interior.

If you don’t do that, the heat builds up on the top and it will warp or crack.

Even if it isn’t around a stove or cooktop, you never know when someone will sit a “Fry Daddy” or some other heat generating appliance on the top. 

Most people just silicone strips of MDF or Plywood on the bottom of the top for a support structure and lay it across the cabinets. 

I am not a fabricator,I’m just an old Decorative surfacing R&D guy working in China right now.  

Some of the other Fabnet members who are all experienced craftsman and/or shop owners, who do this on a daily basis will likely chime in also with some great  advice. 

 

I hope this Helps. Best wishes on your job/ project,

[Tom M]

Don’t be fooled by that crazy Lenny E. Everything he said is spot on. He is a guru of sorts. Like the Drunken Master, so to speak.

There is a manufacturer who used to allow a sort of full substrate as long as you drilled a few hundred holes in it. There are plenty of ways to get near full substrate support and still have heat dissipation. One way would be to cut patterns in the substrate that creates a true “web” look. That spreads the support around pretty well, but allows for surface area to be exposed, venting heat.

I think you need to look at why you need a full support in the first place. Is this an island or peninsula? Is it an open under top, like a worktop over file cabinets? There are few reasons that justify a full substrate in the first place. Why do you feel you need one?

[Lenny E]

Posted By Tom M on 21 Dec 2013 10:29 AM

Don’t be fooled by that crazy Lenny E. Everything he said is spot on. He is a guru of sorts. Like the Drunken Master, so to speak.

Cudnik, these guys won’t steer you wrong. There are more than several millenium of combined decorative surfacing experience on here.

Tom,

Thanks for the compliment. I caught the Jackie Chan movie reference. Back when I was studying Chinese martial arts and had my own Kung Fu school at the time I enjoyed this clip.

This is right after he drunk some lamp oil (he fought best when he had a fair amount of alcohol or related substance  in him). Reminds me of my last meeting with a certain US major SS company (he who shall not be named).

See HERE

Please Keep the comments and helpful hints coming for Cudnik. I didn’t by any means want to dis rail the thread.  

[Tom M]

He really did a great job at resurrecting martial arts movies. Good sense of humor as well.

[David Gerard]

I’m suprized to see that the inside corner is not rounded.
Is that normal for stone fabrication? Does it make a difference when it comes to cracking resistance?

[David Gerard]

oops, wrong thread

[Tom M]

But good advice nonetheless.

[Lenny E]

Posted By Tom M on 24 Dec 2013 07:21 AM

He really did a great job at resurrecting martial arts movies. Good sense of humor as well.

Yep,

I always liked Bruce Lee, Jet Li, Jackie Chan and some others.

Funny story..I was kicking it in Hong Kong and we were down by the waterfront. I was kinda drunk and we came across Jackie Chan’s cigarette boat. Nice boat BTW.

I said “lets steal it and boat across the harbor and  down the  way and park it in between all the fishing boats, junks etc., that many HK families live on full time. It may help him rediscover his roots.”

They talked me out of it. 🙂

[Tom M]

You have wise friends, my friend.

See what I did there?

[cudink]

Thanks for all of the good info. We used a full subtop at a fairly large upper transaction top and the subtop was recessed at least 1 1/2″ from the edge all around. So far we have been doing it this way without any issues.

[Andy Graves]

Posted By cudink on 27 Dec 2013 07:54 AM

Thanks for all of the good info. We used a full subtop at a fairly large upper transaction top and the subtop was recessed at least 1 1/2″ from the edge all around. So far we have been doing it this way without any issues.

We have done this for 25 years without issue. Using silicone is a must and always leave that expansion gap between the two materials.

As long as it’s not in an area with a lot of heat producing appliances, you should be just fine.

[Author]

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