Jacking Up A Sagging Floor Joist

Jack up the ceiling with the bottle jack.

Jacking up a sagging floor joist.

We got muddy because we were in a dirt crawlspace doing just that crawling. Understanding how the entire residential structure fits together is key when significantly altering one portion of the. These days many new floors are framed with i joists a type of engineered lumber that s a fraction of the weight of conventional lumber and capable of spanning greater distances image 6 left. Before undergoing any substantial changes to the structure of the house be sure you consult a contractor or other professional.

Assuming the joists are in good condition the solution to both sagging and bounciness problems is to reinforce the floor. We used 18 000 pound screw jacks 4x4 lumber a circular saw power drill driver and cement blocks. Still if asked to span too great a distance i joists will bounce. Lay a solid wood block below the jack to avoid damaging the floor.

Depending on cost and practicality they could mean beefing up the floor joists or adding new support underneath with new or reinforced posts of support beams. We could not fit full length sisters up there because of space constrictions so we used two sections of 2x8s one 8 feet long and one 2 1 2. Jack up the ceiling slowly about a quarter of an inch per day. If needed extend the jack s range by standing a straight plank on top of it.

It s best to identify problem joists and fix them before installing your underlayment and new floor covering. Sistering is the process of mating up two boards with bolts nuts and washers so that the new board corrects or supports the other weaker one. Depending upon the conditions it is possible to strengthen or repair existing framing members such as floor joists or roof rafters by adding reinforcing material sandwiching the member on either side with plywood is sometimes worthwhile but the plywood must be installed correctly for greatest strength. Correcting a problem joist is an easy repair and makes a big difference in your finished floor.

We jacked up the problem floor joists in the middle from the basement to flatten the floor and sistered in new joists with nails screws and even 5 3 8 bolts with washers. Cost time and skills. If you have access to the basement or crawlspace it is possible to jack up saggy joists until they are level and then sister them so that they remain straight after the jacks are removed. Thre ways to fix a sagging or sloping floor.

As a rule the same kinds of methods that take the bounce out. Total cost was less than 200 while a pro would charge 500 1000.