reasonable time to wait for Landlord's reply

Hi,

Since Saturday I had a leak through the ceiling when it was heavily raining. I had immediately informed the landlord over email but he still hasn't said anything (it's Tuesday now).

I sent another email today asking for his confirmation that he has read my previous email on both addresses that I have from him.

How long is it reasonable that I wait and should I immediately send a recommended letter?

Now the leak has stopped but a few cracks had formed and I am afraid it will start leaking even worse next time it rains heavily.

So far he had always replied to my emails promptly almost so I am surprised that I've not received any reaction so far.

Thank you in advance for your advice!