New concrete floor

[chrisfsi]

Am planning a 3" concrete slab on top of an existing cracked concrete shed floor, with a DPM inbetween the two layers, as the existing floor gets quote damp. The top of the new floor will still be below the DPC in the shed walls. I have a question about creating the new level.

If I were creating a slab from scratch, then clearly I should build a wooden form to establish the new level. But in this case I have existing walls to work against, not a form. I am assuming I should tape the DPM up the walls before pouring (and trim down afterwards..). But how do I establish the new level? Do I just draw a line at the required height around the walls on the DPM? That doesn't give me much to work with in using a levelling board, and I am sure would be obscured by splashes of concrete etc while I'm working in it.

Or should I lay a wooden form round the inside of the walls to the right level, and use them to establish the level? If so, should I leave the form in afterwards, or remove it after the main slab has dried and fill in the gap that it will leave? Shed is planned to be used as a pottery so there is no heavy loading planned.

Thanks in advance

Chris

 

[thomsonayy]

use timber batons to get your level and then screed the concrete across the batons you should be able to get a piece of timber the length you need

 

[chrisfsi]

Thanks - do I leave the battens in afterwards or take them out and fill in the gap they leave behind?

 

[thomsonayy]

you can do either upto u will act as a expansion joint if you leave it in but obviously you will see it and not ideal if you are going to tile over it etc but ok if carpeted