Providing supplemental support to bed slats can prevent the sagging that may occur in mattresses as they get older. Here's a straightforward method for adding slat support to prevent this problem from occurring.
Cut four bed slats equal in length to the inside measurement of the mattress frame.
Check for fit by placing the four boards in the mattress frame at 46 cm intervals.
Measure the vertical distance from the bottom of each slat to the surface of the floor and record each measurement.
Cut the board into four pieces equal in length to the measurements taken in the previous step.
Locate the midpoint in width and length of each slat and drill a through hole in the centre.
Vertically centre a piece of the board you cut earlier beneath the hole drilled in each slat, and attach it to the slat using a wood screw.
Insert the slats with leg attached at 46 cm intervals in the mattress frame. This results in four bed slats with a centre post (leg) supporting each slat at its centre point.
Measure and fit each slat and each support leg prior to assembly as measurements may vary relative to slat location within the mattress frame.