Stacking plastic buckets - how high?

[Sutty]

I use 10 litre plastic buckets which end up with 10-14Kg of honey in each.
I'm a bit wary of stacking them too high in case the bottom one can't take the weight, so try to stick to only two high but it takes a lot of floor space.
Has anyone had a problem with stacking higher?

 

[jenkinsbrynmair]

I often stack them four high

 

[Erichalfbee]

I use 10 litre plastic buckets which end up with 10-14Kg of honey in each.
I'm a bit wary of stacking them too high in case the bottom one can't take the weight, so try to stick to only two high but it takes a lot of floor space.
Has anyone had a problem with stacking higher?

I put old shelves between them to spread the load

 

[NiallD]

The standard 20L Plastic bucket is designed for stacking max three high but I push it to four without issue. The honey crystallises fairly rapidly so gives added stability.