Closeboard Fencing - Jarrett Fencing- buy concrete gravel boards ,Closeboard Fencing. Traditional closeboard fencing is built in-situ and is one of the strongest styles of garden fencing. ... Concrete Gravel Board6ft Long Rock Faced Gravel Board - Oakdale FencingDecorative rock faced gravel board 6ft long x 1ft high. Ideal for use with timber fence panels, either slotted into concrete post or attached to wooden posts with gravel board brackets.