Option B - Measurement method for PWDD

NEC3 and NEC4 Contracts Main options
1

Hello.

We have an Option B, which is silent on the method of measurement.
For concreting we’re allowed 3% wastage.

I’d like to know what is the correct method of measing a simple concreting activity for 1m x 1m x 1m cube

  1. Theoretical - based off of geometry (1m3)
  2. Theoretical - based off of geometry (1m3), with deduction for any re-bar volume
  3. Theoretical + 3% wastage (1.03 m3)
  4. Actual - based on concrete tickets - (this makes more sense for larger pours)

Any/all responses welcome.
Thank you in advance.

2

No.4 - This gives you the most accurate determination.

Not:
No.1 - As you note, it’s not an empty hole, part of the volume is taken up by other materials.
No.2 - Very hard to accurately determine this for every hole.
No.3 - Seems a bit random, where did 3% wastage come from?

Also you order concrete by the cube, so trying to order 1.03m3 is fruitless, it’s either 1m3 or 2m3 (assuming big site and supplier, smaller may negotiate a smaller volume)

3

Cheers for the reply.

Maximum wastage is defined in the WI as the Client is providing the concrete, we’re just supplying the People and Equipment.

4

Hi I think you are mixing things here. The method of measurement will prescribe how you itemise and quantify/measure items for payment purposes, for concreting this is generally based on the dimensions stated on the drawings but without a stated method you need to agree what the method is. The result will probably be the theoretical measure. The wastage factor will be the difference between the theoretical and supplied volume. I suggest you check the WI to see what is stipulated in respect of the volume(s) you can request, eg can you request 3.5 cum

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