With the potential increased liability of the Building Regulations Amendments (S.I No. 9 of 2014) I thought it best to arm myself with a 100mm diameter sphere:
Part K (1.1.19) requires that:
“In buildings which are likely to be used by children under five years old, guarding should be so constructed that a 100 mm diameter sphere cannot pass through any openings in the guarding.”
The argument that you don’t have any children under five years old is risible as the house could be sold to someone who does have children under five.
So, I am armed with my super-accurate 100mm ball and if it passes through any openings then the guarding does not comply with Part K of the Building Regulations.
A special thanks to Geoff Wilkinson who put me in contact on where I could get my ball (ebay)