When the income product to the warehouses need more space and your W/H is full, how can we solve the problem without any extra expensive?

If you don't have any available warehouse space for your incoming products, contact your third party logistics partner and coordinate with them on the availability of space you need. But never ever refuse incoming product from your customer/clients. Try to be proactvie with your customers and plan in future what are their incoming products.

This is a common problem where mostly warehouse is facing, no more spaces for incoming new items whereas management not approved for additional external warehouses. Every supervisors has to be discipline in conducting throughly the system of5S. Identinfy the slow moving and dead stock items. Don't hesitate to bring to the management on the dead stock items for disposal as scrap.

very easy solution giving to you is whenever you have extra product and you don't have a place to store it so why you ask for it from the beginning 

the only solution is to rent a place to store it 

3d party

Outsource or better go for rent in other place.