Most likely your CC&Rs and HOA Documents have a provision that any alterations must be approved by an Architectural Committee or some other governing entity of the HOA.
I suspect if you have all of the appropriate engineering completed and you present your case to the HOA, they would consider it as long as it does not change the appearance of the property to such a degree that it would cause other homeowners to make similar changes to keep the same appearance.
Having said that, HOAs can do whatever they want.
Best of luck,
Broker / REALTOR
"Moving Lives Forward"