The Brew Cabin

Posted: **Mon Jun 19, 2017 4:09 pm**

Really sorry guys - this is probably a FAQ. It also have been answered somewhere else, but I haven't seen it...

Regarding "french" drains: I have my trench all ready. Basic maths gives me the volume of aggregate required to fill the hole, and the specific page on these things tells me I need to order Type B aggregate...

But the supplier sells in bulk '1 ton' bags. How do I work out how much I need to order, based upon the volume of the hole I've dug?

??? Thanks.

Posted: **Tue Jun 20, 2017 8:30 am**

here
They are not 1 ton bags they are bulk bags.

Posted: **Tue Jun 20, 2017 3:47 pm**

Hi Sean,

OK. I'm being thick.
I can find calculators for mixing concrete, calculating bedding mix, sub-base coverage and grit sand volume.
Can't see what i need to work out what I want (bearing in mind that a big proportion of the drainage is going to be voids)

Sorry...

Posted: **Tue Jun 20, 2017 7:01 pm**

As I see it if you're trench calculation works out you need 1 m3 of gravel then that would be about 1 dumpy bag

Posted: **Thu Jun 22, 2017 12:54 pm**

Type B is (very roughly) 1.9T/mÂ³ - there is quite a bit of variation from aggregate to aggregate, but that value is a reasonable 'average'.

So, if you know the volume rquired, multiply by 1.9 for the tonnage. The Bulk Bags supplied by Builders' Merchants are allegedly, about 850kg, but some are as much as 100kg less than that so chjeck before ordering.

The Brew Cabin

Aggregate calculations - How much to buy?