London Diocese has produced some very thorough guidance for churches considering installing Glass Doors in their church.
‘The door to your church is its main point of contact with the outside world. What a church door communicates can be very different to what is communicated by any other building that members of the public regularly encounter. There are many people for whom churches are now unfamiliar places which they may not be comfortable about entering and where they may not immediately feel at ease. So parishes are often concerned that the entrance to a church does not actively draw people into the building and may even deter them from setting foot inside.
For that reason many of them want to install glass doors. It’s been done at plenty of churches across the country and often has made a big difference to the way the building is perceived. But it’s important to know what you want to do and why. Also it’s likely that you’ll be dealing with historic fabric and you may even need to make alterations to it. You’ll need to show that you’ve understood its significance and taken it into account’.