Harbor Siding is Exterior by Mosby’s exclusive private label siding from Royal Building Products. Harbor is a highly energy efficient insulated siding that combines the look and texture of real wood with the maintenance and style of vinyl.

Harbor Siding Cross Section

Energy Efficiency

Thanks to Harbor’s Neopor graphite enhanced insulating foam backing board, this siding boast an R-Value that is 19% higher than traditional insulated siding. R-Value is a measurement that helps determine a materials ability to resist thermal energy. The greater the R-Value the more resistant to heat the material will be.  Not to worry though, as temperatures get colder, the Neopor’s  adaptability allows it to retain more of its R-Value as temperatures dip, which will ultimately help the home retain heat in the winter time.


Harbor Siding 1

Water Resistance

Harbor is a great water resistant siding option. The Neopor backing board is closed cell foam that allows water to pass through it easily and doesn’t absorb water the way other insulation may. This lessens the concern for mold and mildew growth that would compromise the integrity of the siding. An added bonus is Harbor’s strength and durability, which is 240% more impact resistant than fiber cement siding, making it perfect for storm prone areas.

Harbor Siding 2


Harbor Siding is more than its superior functionality; it comes in a variety of colors and styles. Choose from vertical, horizontal and shake styles with trim pieces and shutters available to match the style of siding.


These are the reasons Harbor Siding is Exteriors by Mosby’s private label siding brand. If you are in need of new siding and interested in Harbor, you can give us a call at 314-909-8383 or visit us here.