Hi, I am looking for some advice .

The project is a millwork counter for a commercial cafeteria (solid surface top if it makes a difference to your answer). The base is 3/4" water resistant Douglas fir plywood (DFP) construction finished with plastic laminate (P.Lam). The spec calls for doors to also be 3/4" DFP but with hardwood trim on all edges, and matching P.Lam finish.

I have been asked to consider MDF with hardwood trim and P.Lam for the doors only. The proposal argues that the MDF is less likely to warp compared to DFP. While I agree with the logic, I am concerned (being a high traffic, potentially high moisture environment) that MDF may swell.

I have seen warped DFP doors and particle board that has disintegrated if the P.Lam is compromised even slightly, but have no experience with MDF cores. Other than potential warpage, exterior grade DFP seems like the best choice based on my research.

What are your thoughts/recommendations? Do you have a preference? Are there other options that should be considered?

Thank you.

MEDEX water resistant MDF. I use it in kitchens for painted panel material.

Thanks @Leo G, I appreciate the response. I will look into Medex.

Are there any special treatments to improve screw hold or is that not an issue with Medex? (Again, working from hearsay not experience)

If you are screwing into the face, as long as you don't over tighten and strip the threads in the wood it'll last a good long time.

If you are screwing into the edge it'll work better than regular MDF but not by much. Edge screws into most engineered products isn't that good and that included plywood because it can split on the glue line.

You can buy MDF that is water proof. I have some that has been in a jar of water for a year without change. Wouldn't have believed it. I used it for window sills and porch columns. The stuff is made in the US from rice.

That said I did a coffee shop using mahogany marine grade plywood with laminate on two faces, 3mm edge band. It was the nicest stuff I have ever used, expensive though. You couldn't run fast enough for me to try this on Douglas Fir plywood.

Choosing the right materials for a millwork counter in a commercial cafeteria is crucial to ensure durability and longevity, especially in a high traffic and potentially high moisture environment. Both DFP (Douglas fir plywood) and MDF (medium-density fiberboard) have their pros and cons, so let's break down the considerations for each:

DFP (Douglas Fir Plywood):
Pros:

Water-resistant properties, especially when sealed and finished properly.
More structurally stable than MDF due to its layered construction.
Generally more impact-resistant than MDF.
Better screw-holding capabilities.
Familiarity in working with plywood for construction.
Cons:

Can warp if exposed to significant moisture or not sealed properly.
Heavier than MDF, which could affect ease of installation.
Variability in quality, depending on the grade and manufacturer.
MDF (Medium-Density Fiberboard):
Pros:

Less likely to warp compared to solid wood or plywood due to its uniform composition.
Smoother surface, which can be advantageous when applying laminate.
Easier to shape and cut intricate designs if necessary.
Generally more affordable than higher-grade plywood.
Cons:

Prone to swelling and disintegration when exposed to moisture, especially if the laminate is compromised.
Not as impact-resistant as plywood.
Heavier than particleboard but lighter than plywood.
Given your concerns about moisture and the potential for swelling with MDF, it's understandable to hesitate in using it for a high-traffic, potentially moisture-prone environment like a cafeteria. While MDF is less likely to warp compared to solid wood, its susceptibility to moisture-related issues could be a significant drawback in your situation.

Based on your description, exterior-grade Douglas fir plywood with a hardwood trim and plastic laminate finish seems like a prudent choice. It combines the water-resistant properties of plywood with the added durability of hardwood trim. Proper sealing and finishing techniques will be crucial to prevent warping and moisture-related problems. Regular maintenance and quick action in case of any laminate damage will also help prolong the life of the counter.

For a high-traffic, potentially high-moisture environment, using exterior grade Douglas fir plywood (DFP) with a matching plastic laminate (P.Lam) finish for doors seems like a sound choice. While MDF can be a good option for some applications, it may not hold up well in areas where moisture is a concern. Given your concerns about potential warpage and swelling in such an environment, sticking with exterior grade DFP would be a safer and more reliable choice for the doors. Additionally, proper sealing and maintenance of the P.Lam can help ensure longevity and durability.