causes of sloping floors

[jay156]

I just looked at a first floor in a 60 year old house that is sloping, not toward the foundation walls, like you'd expect if there were settlement, but about mid-span of the joists. Looking at the joists from below, there didn't seem to be any very obvious deflection, but I suppose it might look worse from above than below.

I'm thinking the most probable cause is creep losses and under-sized joists. (They're 2x8's and an 11' span). What do you think? I've seen this once before and was kinda stumped then too. Thanks.

 

[dcarr82775]

My house is about 70 years old and one span of joists has a longer span than the others. There is a noticeable sag in the joists. Just long term deflection on joists that are a little undersized.

 

[msquared48]

If the put in the joists relatively green and they were loaded, they would develop a memory of the deflection experienced as they dried.

Could also be creep as previously mentioned.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[Ron]

Agree..it's probably creep. Pull a string line on the joists (or if you're not old school, use a laser line) and you'll quickly see the deflection that you can't discern from just looking.