Measuring Driven Rain onto a Wall

[neil-c-8]

I need to measure the volume of rain that is driven or blow onto a wall. The reason being I am investigating heat transfer through domestic housing walls as part of my PhD project and water evaporation has an effect on heat loss. I'll also be fitting moisture meters at 10mm intervals all through the wall, but thats a side note. I'll be using a WH1080 linked to cumulus software to give me the overall picture but need wall specific data for rainfall.

I need to buy/make a tipping rainfall gauge that is shaped like a letter box and then mount it to the wall. I will mount several devices at varying heights. So basically the volume of water coming in my letter box is the volume hitting the wall at that height. Following?? I need the data automated so that I dont have to return daily to take all the reading as that would be very very tedious!

Thanks

Neil