New concrete floor with 26mm deep puddle! Ideal for Ducks!

[Warrentdo]

I have a new laid (5 days ago) concrete base 6800x300ish that due to the rain highlighted a huge depression in the middle.

There was plenty of MOT1 compacted with sand on good earth (as approved by BI)

I will be putting 150mm PIR insulation over the top but im not sure that a 25mm bow is ideal.

screed will be going over the top of that but im a little concerned for the insulation being force to bend.

I still have over 150mm thk concrete in worse case in the base.

Any thoughts / suggestions?

 

Warren.

[JohnMo]

Fill the depression with sand, lay insulation, job done.

[wozza]

Self levelling compound ?

[Mr Punter]

Another vote for sand.  You could do sand / cement or levelling compound but it is more work and money.  It is probably about 4 wheelbarrows full.

[Thorfun]

+1 for sand. 'tis what we did in our basement before insulation and screed. was actually recommended by the screed company to 'level' the dips.

[Warrentdo]

Sharp sand so it keys?

 

[Thorfun]

I just used builders sand. You’re just trying to level it off to give a flat base for the insulation to sit on. 
 

note: I’m not a builder and often get things wrong! Hopefully someone who knows what they’re talking about will be along soon. 

[PeterW]

Sharp sand and carry on …! 

[Thorfun]

1 hour ago, PeterW said:

Sharp sand and carry on …! 

just for the record....I'm not digging up my screed, ufh and insulation just to swap the small amount of sand I used for sharp sand! 😉 

[markc]

2 minutes ago, Thorfun said:

just for the record....I'm not digging up my screed, ufh and insulation just to swap the small amount of sand I used for sharp sand! 😉 

Go on! We dare you

[saveasteading]

In case it helps, you might be amazed how out if level most slabs are, and how much us considered acceptable. If there was a roof on, you wouldn't notice.

Agreed as above. Level off with sand. Fill sand or builders sand is fine unless you traipse over it in boots and mess it up. If you have a mixer you might add 10% cement to crisp it up, as it is only 1/2 m3.

 

For interest, and continuous professional development, do you mind telling us what level 'control' was used.

Is the middle low, or are thd ens high...and how thick is the concrete?