My brother is helping our cousins buying a house. Why our building is been appraise?

The house will be under his name I did not know until an appraiser was doing a check in the building that we both owned. Why is it that they are appraising the building I had asked him and he is saying that is not collateral purpose. I am really not happy that he did not let me know what was happenning to our building will this be using the building as collateral or I am just drowning in a gl of water who can help me with this. Help?