garage slab. sand blinding?

[ThrottleHappy]

Hi fellas.

I'm doing the ground work on my garage slab. It's mostly done now but I got a question regards to sand blinding layer before dpm. Do you need to do it when using compacted type 1? Reason I'm asking is 3/4 of the garage is deep enough for both 150mm type1 and sand but the top isn't and I'm struggling to get the depth for both. I only have 100mm depth left in the shallow area so I can either whack some type1 down and skip on sand or dig another 100mm out if sand blinding is needed. I'm pretty sure it's required but rather ask.

Also is it sharp sand or building sand that's used as a blinding layer?

 

[Thepenetrator1]

The blinding is there to stop the mot type 1 piercing the Dpm this would then be letting water/damp through so I wouldn't skip on the sand. The sand you need is building sand as it is softer, sharp sand has more grit in it which is not what you want against your Dpm.
Thanks.