Gaps underneath roof edge tiles

[5oysterman2]

Hi, took a couple of photos of roof tiles. It looks like most have the gap underneath filled in but there are a few that don't have it.

Am i right in thinking that every tile underneath should be filled. If they should be filled, it looks like offcuts of insulation material. Many thanks

 

[catlad]

Left open you run the risk of birds nesting, blocking them up will stop air flow and ventilation.

 

[5oysterman2]

Left open you run the risk of birds nesting, blocking them up will stop air flow and ventilation.

I did think they might be for ventilation, but another concern is that's North facing & worried about water ingress?

 

[catlad]

Water ingress won't be a problem.

 

[^woody^]

Use comb filters.

 

[5oysterman2]

Use comb filters.

Okay, give me a clue what they are?

 

[^woody^]

Google eaves comb fillers. They are made for that exact purpose.

Originally, those Delta tiles would have aluminium eaves fillers, but you may not be able to get them now, but Google for those too.