Freefoamand#039;s plain soffit board are 5-metres in length and have a thickness of 10mm with straight edges.This soffit comes in a smooth finish in storm grey, which is the darkest shade of grey we offer in our soffit boards range.Soffit boards are used to close the gap at the eaves between the rear of the fascia board and the wall. For a visual explanation, please take a look at our short video which explains which parts go where in the roofline construction. Soffit boards are non-load bearing.