Subfloor bearers need to be strong enough to hold the rest of the floor up. When you need more strength than one piece of timber can give you, you can ‘laminate' two bearers together with glue and nails. Apply a generous amount of construction glue on the surface of one bearer. Place a second bearer on top of the first and slide it around to spread the glue. Then line the two pieces up so their edges are flush and double nail them along the whole length.