Cot Mattress

We have bought this mattress for the cotbeds:
http://www.mothercare.com/Premium-interior-mattress-Spacetec-COOLMAX/dp/B0030SQNLE/sr=1-1/qid=1269978666/ref=sr_1_1/279-2492960-9032924?_encoding=UTF8&m=A2LBKNDJ2KZUGQ&n=206265031&mcb=core#productInfo

The description of the mattress says:

Removable cover containing Spacetec™ and COOLMAX® reduces overheating
Silver ions in COOLMAX® freshFX® help prevent bacterial and fungal growth
COOLMAX® freshFX® keeps the mattress fresher for longer
Machine washable cover at 60°C, the temperature required to kill dust mites
Your baby can still sleep on the mattress whilst the cover is being washed
Wipeable, waterproof layer
Quality cotton blend cover offers durability and additional comfort

My question is this: because it has a wipeable, waterproof layer, will I still need plastic sheets or whatnot to protect the mattress from wet bottoms?

The main reason we chose this mattress was because it advertised that it reduces overheating and I'd rather not use plastic sheets if possible but obviously I want to protect the mattress.

since it says wipeable, waterproof layer... I think it sounds perfect, you shouldn't need anything else 

Agreed.

Cool. Thanks ladies.