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 anthracite grey.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.