How To Jack Up Floor Joists

How To Jack Up Floor JoistsHaving a dip anywhere in the flooring of your house is nothing short of a nightmare. The reason behind such issues is often old and sagging joists that refuse to do their job. However, with just a few tools, including your precious jack, you can easily lift the floor joists.

As this slight dip can birth some awful and disastrous situations, it is critical to take care of it in a timely manner. Lucky for you, the fix for this issue is quite simple and can be done in a short period. So you will not need any heavy-duty machines or the assistance of a specialist.

After spending hours searching on the internet for the right procedure, I realised how even a minute mistake can damage the flooring. So, in the article below I have jotted down the whole process in simple and easy steps with the dos and don’ts. Without wasting any more time, let’s discuss how you can jack up the floor joists of your house.


How To Jack Up Floor Joists

You will be able to jack up the floor joists of your house very conveniently with the following simple steps.

Tools Needed

In order to jack up the floor joists of your home, you will need a couple of items. The first thing that you need is a hydraulic jack. Here comes the tricky part, you need 2 to 3 jacks for this process. The list also includes a couple of wooden blocks, a thread and a measuring tape. The height of the wooden blocks should be according to the height of your floor joists, minus the height of the jack.

Measure The Depth Of The Sagging Area

Before your start pumping the floor upwards with the jack, first, you need to determine how much the floor joists have sagged. For this, take the thread and tie it from one end of the floor to the other. Tie it a little below the edge. Then take your measuring tape and hold it on the edge and measure till the thread. Measure both edges and then move to the area that has sagged. Hold the measuring tape to the edge and bring it down till it reaches the thread. The measurement of this area will be less than the edges, due to sagging. The difference between the corner and the centre measurements is basically how much the floor joists have slumped.

Methods Of Placement

There are two ways to place jacks and wooden blocks. The first method that we are going to use has the jack at the bottom and the wooden block on top of it. On the other hand, the second method has the wooden block at the base and the jack on top of it, touching the floor joists. For the second method, it is critical to place a metal plate between the floor joists and the jack. Otherwise, direct contact of the jack with the floor joists may cause some irreversible damage.

Place The Jacks

Once you have gotten the measurements, take your first jack and place it under the sagging area. Put the wooden block on top of the jack and fix it in its place till it is tight enough and does not budge. Put the second jack a couple of feet away and place the second wooden block on top of it. Do the same with the rest of your jacks, and if you are only using too then that will work too. Make sure that you hammer the wooden blocks to push them in their places.

Pumping The Jacks

Start pumping your first floor jack a little bit. Make sure not to raise it an inch directly. If you need to raise an inch, do it in 4 settings of a quarter of an inch. Do not pump your jack instantly an inch as that will cause more problems. Make sure that you pump the rest of the jacks the same amount as your first one. Leave them for 10 to 15 minutes and then start pumping again.

Measure The Center Area Again

After you have pumped all your floor jacks, you can take the measuring tape and measure the centre area again. There will be an immediate difference between the initial measurement and the post-jack measurement. This means that you have successfully lifted and jaked up the floor joists of your house. Let the jacks sit for about 10 days to 14 days. After this period you can remove them, Lo and behold, no more sagging floor joists.


As frustrating and annoying as it is to have sagging floor joists, the process of lifting them is quite simple. However, simplicity is only applicable if you follow the right procedure with precautions. To steer clear of any mistakes, give a thorough read to the process that has been shared above.

Janathan Greez
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