HMR board is made by adding a special resin to the board which gives it extra moisture resistance. This resin can be added to numerous types of board, and so not all HMR boards are the same (but their moisture resistant properties are). Common materials for HMR board are engineered woods such as chipboard and MDF.
HMR board is perfect for damp and humid environments like bathrooms. Think about how your bathroom steams up during a shower and how much water is splashed on your vanity every day – the standard board will swell and split when exposed to water, but HMR will not. HMR will also reduce the risk of moulds and bacteria growing in your board due to dampness creeping in. For these reasons, it is crucial that you choose HMR board when upgrading your bathroom vanity, not just if you don’t want to be replacing your vanity a few years down the line, but also for your health.