Best substrate for modern flat doors on a bath vanity

[Joe Jensen]

I am remodeling a couple of bathrooms and I am building the vanities. I am considering going modern and doing very clean design vanities with flat panel doors and drawer fronts. They would be veneered in something special, maybe quarter sawn Sapele or something like Zerbra wood. The question is what substrate to ensure they stay flat over time, and also something that will handle a bathroom environment. I'm hesitant to use MDF. I have used Baltic Birch with success but it seems like the stuff I get for the past few years warps more than the stuff from 10-15 years ago.

Suggestions?

[Peter Quinn]

The following link is for one brand of a class of "water resistant" or "water proof" MDF board products available for moist or exterior environments. I used some for a bead board job a few years back in a bathroom. I placed a cut off in a bucket of water outside and left it there for several weeks. Took it out, dried it off. Unaffected by the moisture. Not your regular MDF at all. I have not tried to veneer the stuff. Not sure how the moisture resistance affects the use of water based glues?

http://www.extira.com/

I have used baltic birch which is available in an exterior rated water resistant format as a substrate for sawn veneers, but I fear it would not be the best substrate for commercial veneers as the grain of the birch may telegraph through a very thin face layer. Perhaps some of the backed or multi layer veneers would be more appropriate over a plywood substrate?

[Jamie Buxton]

I dislike working with MDF. It is nasty stuff. But of all the usual substrates, it is the one that is most likely to be flat when it arrives at my shop. (Even MDF can be non-flat. The distributor has to store it flat. So Home Depot MDF doesn't count.) I think it is also likely to stay flat in service when covered with veneer front and back.

Drawbacks to MDF... It sags if used for shelving, so use it only for vertical applications. It turns to mush if it gets wet, so properly encase it with veneer etc to protect it from that. It doesn't hold screws well. You can glue in wood plugs where hinge screws need to go. Or you can use hinges with fastening schemes designed for MDF -- press-in plastic dowels or the like.

[Jim Matthews]

What about Azek?

[Bill White]

Extira is a great alternative. That stuff is heavy. I used it on exterior columns for our last home. Just gonna need a good finish on it.
Bill

[Jamie Buxton]

What about Azek?

Azek is PVC. I wouldn't expect woodworking glues to stick to it, so veneering and edgebanding it would be dicey.

[scott vroom]

My number one choice would be MDF with Blum Inserta hinges (no screws). I've had MDF doors/drawer fronts in a bathroom vanity for 12 years and have had zero problems with moisture. MDF get's an undeserved bad rap for bathroom applications IMO.

[Bill White]

Extira is an mdf product.
Bill

[Peter Quinn]

My number one choice would be MDF with Blum Inserta hinges (no screws). I've had MDF doors/drawer fronts in a bathroom vanity for 12 years and have had zero problems with moisture. MDF get's an undeserved bad rap for bathroom applications IMO.

Have you ever had a 4 year old pee all over them? I have MDF raised panels in a linen closet in my bathroom, and I can attest that with a good finish it can withstand the potty training years. Better than me actually! Shellac was the sealer, water borne acrylic top coat. Not sure how they would survive under the sink directly though?

[Jim Matthews]

I've seen hot melt adhesives do amazing things with wood veneer, but the thickness of the veneer may contribute to the adhesion character.

Another alternative would be honeycomb core panels. The yacht builders in neighboring Rhode Island fabricate most of the contact surfaces on a hollow substrate.
They're certainly durable, in a hostile environment. I don't know which is worse to handle; MDF dust or the adhesives necessary to bond wood veneer to plastics... it's an interesting problem.