lesliekatzman,

We would not recommend using any type of MDF/MRI product in an exterior application. There are some very good alternatives for this in either a beaded T&G board or in sheets. I recommend either Wolf PVC, Boral TruExterior or NuCedar Beadboard sheets. All are either in-stock at Niece Lumber or has a quick special order lead time. Please see the links below or give us a call 609-397-1200:

https://www.wolfhomeproducts.com/system/files/Boral_TruExterior_Trim_PRODUCT_&_INSTALLATION_GUIDE.pdf

https://www.gardenstatelumber.com/products-programs/pvc-program/

thanks niece lumber- my issue with some of the other exterior rated beadboard products is that they have a mere suggestion of the beadboard grooves while nantucket beadboard has grooves you can see. We installed the hardiboard 'beadboard' for our soffit and the appearance was extremely disappointing. Looked like a stamp- I don't think you will even see the grooves once it is painted.

Forgive my delay in responding as this somehow got buried in my email, we used traditional tongue and groove fir wood on this porch. Other options to consider would be Boral Fly Ash Material or Azek PVC material. All our best!