DPM under weight bearing concrete slab in back garden?

[Ian H]

I’ve dug our for a hot tub base in my garden, it weighs about 300kg plus water.

I’m going to line the hole with 4x1 but should I also be putting a DPM under the concrete or does it not need it with it being outside?

 

[oldbutnotdead]

Put dpm down, it'll help the concrete cure properly. Do you need/have you thought about drainage, water supply and power supply? First 2 less important than the 3rd....
Some hardcore under there wouldn't hurt

 

[JohnD]

Where will you put the base layer of insulation slab?

 

[Ian H]

Put dpm down, it'll help the concrete cure properly. Do you need/have you thought about drainage, water supply and power supply? First 2 less important than the 3rd....
Some hardcore under there wouldn't hurt

Yes, there’s a drain a tap near the front left and the power will come under the fence at the back left.

 

[Ian H]

Where will you put the base layer of insulation slab?

I was thinking under the concrete with an upstand at the sides.