Fix a Deck that is Sagging in the Middle

Definitions:
posts: 4" x 4" or 6" x 6" boards that are placed on or in contrete that stand vertical to provide support to deck.

joice: board(s) that are parallel to the ground and provide the support for the decking. They are typically 2" x 10" boards.

decking: The decking is the boards that are used as the flooring.

A deck that is sagging in the middle does not have enough support for the joice that are underneath the decking. This is a simple fix with the right tools. The most important thing to remember is that if you are in the hospitle or dead you will not be able to enjoy the deck so think safety first.

Materials Needed:
Posts (4" x 4")
Joice (2" x 10")
Hurrican Ties (go to a hardware store and ask for hurricane ties, they only cost about $2)
Ground Jack (rent at local store for pretty cheap)
Joice Nails
Deck Blocks
Posts Ties (to secure post to beam, ask the hardware associate, they will point them out to you)

Step One:
Determine the length of the support beam. If your deck is 12' by 12', you will need a beam about 8' long. I prefer to use two 2" x 10" boards as the support beam. Do not use just one board unless it is at least a 4" x 6".

Step Two:
Prepare the ground for the jack by leveling or using concrete blocks directly underneath the center joice of the deck. On large decks, two jacks may be required. If so place them approximately 5' - 7' apart.

Step Three:
Jack the deck up until the center is level. Be extremely careful that the jack does not slip and the heavy deck does not fall on your head. In other words keep way clear.

Step Four:
Take several scrap 2" x 4" 's and stand them up next to the deck with bottoms squarely on the ground. Nail them to the sides. This will create an extra added safety measure in case the jack fails.

Step Five:
Secure the 2" x 10" 's as the beam using the hurricane ties. Do each end first and then secure the rest.

Step Six:
Determine where you want each post. You will want them no greater than 8' apart and at least one at each end.

Step Seven:
Use a plum line to determine where to place the deck blocks. Simply place a nail in the bottom of the beam and drop a string with something heave on the end. Let it hang until it is straight and then mark the ground where the center is.

Step Eight:
Level the ground where you marked and place a deck block. The deck block is designed to hold the deck posts. Make sure the block is level and plum.

Step Nine:
Measure the distance between the beam and the block. Cut a 4" x 4" post to that measurement adding approximately and eigth of an inch. Place the post in the deck block first and then bring squarely underneath beam using a post tie. You should have to use a hammer to knock the post into place. Repeat this process every eight feet and you will be done.

Step Ten:
Remove jack and make sure deck is secure.

Note: You may have to replace the decking boards where the deck sagged due to warping.

Congrats! You just saved yourself at $500 by doing this job on yourself.