Asking for trouble?

[rdesigns]

Recently, I toured a beautiful new house with many tasteful and high-quality features. The dominant feature of the kitchen was the island counter, about 5' wide and 8' long.

The 1-1/2"-thick top was built up of 2 layers of solid walnut boards, and was very impressive, but the potential for trouble is that the entire perimeter is wrapped with a decorative molding, mitered at the corners, including across the 5' expanse of end grain. No allowance for seasonal wood movement.

The slab is finsished with a heavy coat(s) of polyurethane, and the indoor relative humidity here ranges between about 20% in winter to about 40% in summer--not a huge variation, but, still, do you think there will be enough movement to cause problems?

 

[mouppe]

Yes. No doubt about it.

The temperature and humidity in a kitchen varies more than any other room in a house other than a bathroom, even with a good HVAC system. You have steam from cooking, heat from the oven etc.- even with a good exhaust system, it's inevitable that some moisture will escape.

The poly may delay things a little, but in time it will either produce a gap between the skirt and top, or a split mitred corner. Across a 5' slab of walnut, you could easily see 1/2" of movement.

If I were to make such a counter, I would either leave it with no skirt or make a maple skirt for the long sides and add maple breadboard ends.

 

[rdesigns]

I agree--the general contractor, however, thinks that spikes in the humidity will be short-lived, and that the poly will protect the slab during those short intervals, which might be true, but I still think the long-term seasonal changes will cause trouble.

 

[Rick Christopherson]

First off, if the counter is completely bordered by trim, there is no guaranty that the field is really made from solid wood. Just because the person showing the house claimed that, doesn't make it so. If anything, it may just be a custom veneer layup.

As for the survivability, it is more survivable than many woodworkers think--as long as it is done properly. 5 feet wide is a little extreme, but I have done this at 3 feet wide and it still survives 20 years later (my father's desk top). The seasonal changes in most houses is very small, and as long as the rate of absorption into the wood is longer than the time of the seasonal change, it will remain steady.

 

[rdesigns]

Interesting...

As for the possibility of the top being other than solid stock, there is no question about that--I had the same question for the builder, asking him if there could be a core of plywood. He said no way; he was in the cabinet maker's shop during construction, and knows for a fact that it is solid stock.

So, it seems the answer is probably: Time will tell.

I have seen alder frame and panel interior doors here with really wide panels--up to 32"--and some have been stable for several years, and others show shrinkage where the stained panel has pulled out of the frame enough to show a 1/4" white border along the edges. I'm not sure what the explanation is.

 

[Jesse Cloud]

Just another data point, I have a 42 inch wide walnut kitchen table with breadboards.  In the humid season, the panel expands about 1/8 inch beyond the breadboards on each side.  My humidity variations are extreme though (we live in the desert and cool with evaporative coolers).

If yours behaves like this, you can count on trouble.

 

[mouppe]

Whether you get away with it or not doesn't make the construction method correct. The top should have been built to allow for expansion, and if it doesn't cause a problem it's down to luck rather than judgment.

And what if one day the top is moved somewhere where there is more exposure to seasonal change?

 

[Rick Christopherson]

Putting the question of survivability aside for the moment, it does beg the question of why they would do this in the first place. It's not even a matter of the solid wood by itself, but 2 layers of it. That doesn't make any sense, except for simply being able to "market it" as being solid. Maybe it originally started out to not have any border trim, but they weren't satisfied with the end grain.

Even if it were deemed survivable, I still wouldn't take the risk (and cost) when there was no clear benefit.

There is the other possibility that the contractor isn't telling the truth (for marketing), or doesn't even realize he's not telling the truth. He could have seen an MDF core and mistakenly though it was solid because the colors are very similar. I can't imagine a professional cabinetmaker doing this deliberately when there is no net gain, but substantial risk.

 

[RONWEN]

Putting the question of survivability aside for the moment, it does beg the question of why they would do this in the first place. It's not even a matter of the solid wood by itself, but 2 layers of it. That doesn't make any sense, except for simply being able to "market it" as being solid. Maybe it originally started out to not have any border trim, but they weren't satisfied with the end grain.

Even if it were deemed survivable, I still wouldn't take the risk (and cost) when there was no clear benefit.

There is the other possibility that the contractor isn't telling the truth (for marketing), or doesn't even realize he's not telling the truth. He could have seen an MDF core and mistakenly though it was solid because the colors are very similar. I can't imagine a professional cabinetmaker doing this deliberately when there is no net gain, but substantial risk.

That's where I would place my bet -- it's hard to imagine a professional cabinetmaker choosing to build that way.

 

[Julian Tracy]

Without a doubt, a nice Walnut plywood would be the ideal material in this use.

To build it with solid lumber would be a poor choice.

JT

 

[rdesigns]

That's where I would place my bet -- it's hard to imagine a professional cabinetmaker choosing to build that way.
[/quote]

That's the puzzling aspect of it to me too. The climate here (SE Idaho) is relatively forgiving of transgressions of classic woodworking rules. Added to that is the fact that cabinetmakers here who compete in the homebuilding arena do not have formal training beyond that highly competitve and very limited scope of work. They know how to set up machines and spray on finishes, but I've never met one yet that understood the difference between radial and tangential shrinkage or many of the other basics of wood behavior.

BTW, there is no doubt about the fact that the top is built up of solid stock.

So, as I said, time will tell.

 

[Lbob131]

What would happen  if you glued  two  layers of walnut  90 degrees  to each other?

Flooring contractors regulary  glue hardwood floor to the  concrete/cement base below  over  incredible widths.
I think they make the claim  that   the wood moves in union  with the concrete. Well it would have  no other  choice  if its glued solid  to  concrete.

But how much does concrete move? I would envisage the wood wanting  to move a lot further  than the  concrete.

 

[rdesigns]

What would happen  if you glued  two  layers of walnut  90 degrees  to each other?

Flooring contractors regulary  glue hardwood floor to the  concrete/cement base below  over  incredible widths.
I think they make the claim   that   the wood moves in union  with the concrete. Well it would have  no other  choice  if its glued solid  to   concrete.

But how much does concrete move? I would envisage the wood wanting  to move a lot further  than the  concrete.

Wood floors are usually built up with relatively narrow individual boards that are not joined one to another; this means that the expansion/contraction does not accumulate across the width of the installation--each board moves only slightly, and not enough to matter.

As for the comparative movement of concrete vs wood, I can't offer hard numbers, but I am certain that wood moves far more than concrete.

 

[tbellemare]

Flooring contractors regulary  glue hardwood floor to the  concrete/cement base below  over  incredible widths.

I thought that would only be done with laminate flooring. We have some flooring contractors on here - perhaps they can chime in?

Tom

 

[tjbnwi]

Engineered floors can be glued in place. Laminate floors are normally floating and only glued down on stairs. Solids are most commonly fastened down.

Tom

 

[tbellemare]

Thanks, Tom.

Tom