Hollow soffit J trims are the most common starter trim option and are fixed with polytop pins or screws.The longer side of the J trim should be fixed to the underside of the batten fixed to the wall, or the underside of the soffit bearers. Freefoamand#039;s hollow soffit J trims are 5-metres in length and are finished in a smooth dark grey.Freefoam SoffitsA lightweight range of solid and hollow soffits that are designed to work with the fascia range (and all other size variants.)It is recommended to use Freefoamand#039;s P30 or P40 Plastop Plastic Headed Pins for soffits.Freefoamand#039;s soffit boards are BS EN 13245-2:2008 certified.