How do you put in new joists when you have old joists in the stone foundation?

Answer 1

Joists are support beams made of timber (wood), steel, or reinforced concrete. These beams support the floors of each level of a house or building, as well as the roof.

You need to first identify any trimmer joists, those around staircases or chimneys. Second, and most importantly, you need to identify the "load bearing" joists. Third, remember you cannot remove joists without FIRST installing a temporary joist right beside the one you intend to remove. Consult the DIY article in Related Links.

The main premise in joist replacement is to correctly re-support the house with new load-bearing joists, but to do so, you must support the load with temporary supports before putting in the permanent replacements. This is accomplished with jacks that support the house and temporary joists. I'm NOT an expert, BUT if I remember correctly, once you've supported the main load points, you insert a temporary joist beside the old or support it on a jack for every joist throughout the area in which you are working, (e.g. a basement). Then you replace the highest load-bearing joists first. Last, you'd replace the lowest-load-bearing joists. So it is a 3-step process: (1) insert temporary joist right beside the old (2) remove/replace the old with the permanent joist with a correct load-bearing wood/timber/steel/concrete (3) remove the temporary joist.

If you are not a construction worker, be sure to consult an expert first to get information about how to calculate the "load" factors for the specific house. You may want to hire a contractor to do the job.

NOTE: If you remove existing joists incorrectly, the risk is that the load in that area is higher than in other areas, so the structure could:

• be weakened
• exert a "twisting" on the structure due to load forces
• be damaged or may collapse.

Disclaimer: This answer is formulated from knowledge gained when working with a contractor during home construction, BUT not as a skilled worker. Therefore, please consult a professional for your safety and to hear a professional's advice / direction.