Another alternative is to attach a builders strap to the reverse of the beam prior to any plastering or decorating. The strap top and bottom tails of the strap are then screwed to the supporting wall and is hidden by the plasterboard.
Please note, oak and plaster do not mix and therefore we would stronger recommend covering your oak beam with plastic or suitable material to protect from any splashes of plaster.
The diagrams to the right shows an X-ray view of how this would work.
We would only recommend this for up to 140mm x 140mm x 1220mm
(48″ x 6″ x 6″) due to the weight of the beam. Advice should be taken from your installer if in doubt. An alternative and more convenience approach would be our invisible fixing option.
The bottom picture shows, on the right hand side, a pegged option by face fixing the beam straight to the wall.
Oak contain something tannin acid and ordinary steel screws will react with the oak and may, over a long period of time, start corroding the screw. We would recommend using stainless steel or passivated screws for attached the builders strap to the oak beam. A suitable screw should be used fixing the strap to the supporting wall.