What causes uneveness in Concrete floors?

[tw08]

Hello!

I have an apartment in a new(ish) building with concrete floors throughout. I have noticed by walking over it even over the carpet the floor is not even. It dips and undulates. It's not a problem really, we have a combination of carpet in some rooms, laminate floor in the living room (which is a little spongy in places but only if you are aware of it) and ceramic tiles in the kitchen, but I'd just like to check, what causes uneveness in concrete floors? I've been in lots of buildings with concrete floors and most have dips and bumps somewhere but some are worse than others, and my apartment building is one of the most uneven! Is it caused by continued walking, standing heavily (concentrating weight on one spot), or by placing heavy objects on it? Or is it the way it was laid when built?

Many thanks.

 

[noseall]

screed!

it is the finishing layer to a lot of concrete floors. it compresses as you lay it. the more you work the screed the more it compresses.

on a typical floor screed, the outer edge of a room will be laid first. this forms the levelling screed. this will be rather compact because the user will have worked his float over it rather a lot.

next you fill in between the levelled stuff and then drag a straight edge along the floor using the edge stuff as a guide.

this then gets rubbed up and subsequently compresses, but at a different rate to the edge screed. you end up with slight dips unless you account for this when rubbing up.

that's my theory anyhow.

 

[tw08]

Thanks for your reply!

That's interesting. So basically the eveness of a concrete floor is ultimately down to the quality and skill of the builder/floor layer?! Heavy objects, walking and standing on it will not affect the level of the surface?

 

[noseall]

Thanks for your reply!

That's interesting. So basically the eveness of a concrete floor is ultimately down to the quality and skill of the builder/floor layer?! Heavy objects, walking and standing on it will not affect the level of the surface?

no. but a screed can 'lift'. or a floor can subside. pedestrian traffic or domestic loads have little structural effect upon a concrete floor.

heating pipes can cause a screed to lift particularly at vulnerable junctions.

 

[tw08]

Ok. Thanks for the info.

I definitely don't think the screed has lifted - it doesn't move when you walk on it, it's very solid, I just don't think the screed was laid evenly to begin with!

Thanks again.