Now place the iron girders horizontally on the floor in such a way that the height of the iron girder in the that position is more or less the same as that marked on the house’s wall earlier (Step 1).
Add more iron girders in a series until you have the area of the deck covered, thus keeping them a few inches apart. Using an iron driller, make drills through the girders and fix them with the help of bolts or Hilti gun to provide strength.
To fix the wooden boards strongly, drill through each of them and the iron girder simultaneously. As you are done with the drilling, insert bolts in each hole and tighten the screw from below the wooden board.
Repeating the same procedure for each of the wooden board, fix all the wooden boards one by one till the whole area is completely covered. For instance if there is some space left, fill it by cutting a wooden board accordingly and fixing it the same way.
As it is important to protect the deck from the weather, so your final step is to coat the deck with cheap decking oil, preferably acrylic based decking stain since it is guaranteed to last for 2 to 4 years.