Use a wireless repeater to strengthen the wireless signal as you go through your home.
How to boost cell signal in house with metal roof.
With external antenna elevated a minimum of two feet from the metal roof you can be sure the reception will be captured and boosted.
Steel or aluminum walls are very good at blocking wireless signals.
The cables should come with the power booster.
Metal buildings offer a challenge for cellular signals.
Even if you have a perfect signal outdoors you might get little or no cellular coverage indoors.
The wireless repeater will also extend the effective range of your wireless network although it will not have as great of an effect as it should due to the metal roof.
The easiest way to improve the cell phone signal inside a metal building is to use a building cellular signal booster system.
However if you have good to excellent cell phone reception now the metal roof should not have any noticeable effect.
See more on metal roofing here.
What causes bad cell phone reception at your house.
These systems can boost the signal indoors for one or several cell phones.
In a nutshell metal roof or not the type of building material is irrelevant the cell phone signal will be injected into the internal space via a special high quality cable.
This is the most effective method of treating the problem.
If your home has energy efficient windows a metal roof or siding or is made from concrete or brick these materials can all block signal.
An electronics store should be able to sell you a cell phone signal booster and an external antenna.