MDF as Sub-roadbed

I am about to replace some cookie-cutter roadbed - cork on 1/2" plywood. My son suggests using medium density fiberboard (MDF) instead of pylwood. (He has found this a workable material in many projects, but not in HO model railroad projects!)

So, is MDF an acceptable alternative to plywood as a sub-roadbed? What do you folks think?

Thanks in advance.

Andy

You ask a timely question. I am in the process of building benchwork on my new layout and I had the same thought. I doubt very much whether MDF would work as a plywood substitute in a model railroad context. It is my understanding that MDF is not used as a plywood substitute because it does not have the shear strength of say a CDX product. I would be interested in hearing from any contractors or wood workers out there.

My concern is that the MDF possibily lacks the dimensional stability plywood offers. Call me a chicken, but if I were you, I’d stick to what’s worked well for all these years – plywood.

You might contact the American Plywood Association (www.apa.org, I believe) and ask someone there whether MDF is a good substitute for plywood in this situation.

Paul Schmidt
Associate Editor
MODEL RAILROADER

Make that www.apawood.org. One of the things the APA does is certify engineered wood products and sheathing.

Paul

I wouldn’t use MDF for subroadbed, mainly because it isn’t meant to be nailed into, or even screwed into, unless holes are pre-drilled close to optimum size. Also although it ‘machines’ well, this really applies to tablesaw,CMS, drill press and router table work. Cutting MDF shapes with a jigsaw is no fun.Plywood is best for the initial work, and any changes later.
I use MDF for general carpentry projects like drawers and drawer fronts. Only place I use it on the railroad is for bases for buildings. It’s really good for that.

I tried MDF - 1/2" on with supports on two foot centres. It was way too flexible.
1/2" plywood on the same centre distance to be fine, although next time i will use 16" centres.

The MDF is flexed too much. Its also very dusty when cutting, far more than plywood.

You learn by trying right?

Kevin

Plywood it is then!

Thank you Jim, Paul, Mike, and Kevin for responding. And like you said Kevin, “You learn by trying, right?” - true. But it is also nice to get information from guys like you who have had past experiences and can say “whoa!” to the MDF idea.

Thanks again.

Andy