The sagging floor was the symptom and somewhere under the house there had to be a cause.
Shoring up floor joists.
Your foundation may not be the problem.
Whenever anyone walked across the kitchen floor in the home where this old house general contractor tom silva grew up teacups trembled in their saucers and pots and pans rattled on the stove.
Eventually his father a carpenter went down to the basement with tom in tow and reinforced the undersized floor joists.
Tack a beam under the sagging joists.
For instance you may have a dining room floor that end to end is level but between those two points are various sags and dips.
By jacking up the ceiling of the basement you.
The longer the distance a joist spans without support the more it will flex.
Where these repairs are not sufficient also consider shoring up joists or beams that were cut drilled or notched for pipes wires or ducts.
This type of repair may require a building permit and usually requires extensive.
Set a hydraulic jack and post under the beam and jack up the joists about 1 8 in.
Floor joists and posts support the flooring and damage to them is the most common cause of a sagging floor.
Nailing two 2x4s together will work to span about three joists unless the sag is under a weight bearing wall.
Place support of the floor joists with wood studs.
Shows raisinge a sagging floor gradually with bottle jacks.
By building a wall under joists you divide the span.
Well after doing the navy seal crawl up under the house we found that the joists that were supporting that floor were not actually attached to the sill plate any longer as seen in the photograph below.
Photo by richard howard.
In some cases pouring floor leveling compound will fix the problem.
Stretch a string across the floor to evaluate the amount of deflection then use it as a benchmark for improvement when jacking.
It was nerve racking tom recalls.
If you build a wall to support joists be sure to place a stud directly and tightly under each joist.
The floor above will be stiffest if you place the wall in the middle of the joists.
Instead it may be an issue with joists and beams below your floor that require shoring up.
For more serious weaknesses you may need to shore up the floor joist structure with a cross beam and lally posts.
To check joists and diagnose the problem a pro must pull up the flooring and the subfloor to see what shape they re in.
