Good evening. I live in a small terraced house which was built in early 1900. The external walls are solid brick. Is it ok to put some screws into it in order to put some shelves up or is it better not to touch them in order to prevent some humidity getting in. Also, the internal walls are made of wattle and daub. Can I use wall plugs in order to put some shelves up or the wattle and daub is not strong enough to withstand the weight of shelves. Thanks in advance for your time.