[mikegina]

Seeing the way foundations are laid nowdays... 'why' concrete floors in basements are cracking is easily answered. I am curious how much is too much and a legitimate concern?

Tarion (in Ontario) sites that it is "Ok if it was anticipated in the design"

What kind of standard is that???!!!

Has anyone gone through issues with cracking in basement floors and can provide some guidance? (Some sort of metric?)

 

[SPS-1]

"Ok if it was anticipated in the design"

Sounds reasonable to me.

I don't think I remember seeing an unfinished basement floor without cracks. I have cracks in mine. But I don't have any water intrusion issues. I guess the builders anticipated the floor possibly cracking, and put down the proper drainage, etc so it would not be a problem.
Somebody on this forum once posted a great quote that I will never forget: "there are three sure things with concrete; its heavy, its going to crack, and nobody is going to steal it from you".

Cracks on a basement wall are a different issue, since whatever minimum code is for extrerior protection of a foundation wall, its not sufficient. But again, cracks are anticipated, and measures are taken to mitigate the consequences. (even if it can be argued that the measures taken are inadequate.)

Sorry, I can not give a quantified anawer on what is excessive cracking a new basement floor, but if you don't have any water intrusion issues, likely its not a reason to worry.

 

[mikegina]

I am assuming that it sounds reasonable - if you are aware what the steps are to mitigate for the detrimental effect of their presence, and you know that these steps were taken? And how can you confirm that these steps are taken?
I would be curious what the steps are to 'plan for this' other than having a mandatory weeping tile/sump pit... lousy jobs are ok because all water goes to the sump pump and it will never fail?

Is 'normal cracking' hairline, or 1mm wide cracking everywhere you look? (In my house, the largest 'uncracked' area is probably 4 sq. metres in a 2000 sq. ft basement) All cracking is 1mm wide, little hairline, and I think the 'slabs' are starting to develop a bit of an angle to them (high in the middle sloping down towards the walls)

Again... I think there has to be some visual threshold or things to look for that suggest there are relevant concerns to bring up.
The issue may not necessarily be the cracks in the floor, but stress issues (causing wall cracking or worse).

 

[GBrackins]

from the National Association of Home Builders "Residential Construction Performance Guidelines"

Observation: Interior concrete slab is cracked.

Performance Guideline: Minor cracks in concrete floor slabs are normal. Cracks exceeding 3/16-inch in width or 3/16-inch in vertical displacement shall be repaired if the slab is in conditioned space or the crack interferes with the installation of finish flooring.

This is the only standard I know of.