As Charles states above you cannot just modify or replace trusses. That is all part of an engineered system designed in its entirety for the live loads and dead loads shown as an attic, not for living space.

This is the agony I go through sometimes when designing home. I just know someone is going to want to use all that un-utilized space above the ceiling and below the roof some time in the future.

Yep. Yep. We said never on space above the garage and then kind of wish we hadn't said that.

Unless the soil is an issue, the foundation and first story walls are likely to be adequate.

It is pretty common in the UK. They sell aluminum systems called loft conversions. Wish it was more common here in the US.

Looking at the "loft conversions" from the UK, it looks like just another way of altering the trusses that would still involve an engineer and shifting the liability onto those involved in the alterations. The decision would still remain, "How much do you wish to pay?"

https://ecotrus.com/ecotrus/

Altering the trusses does not address the lack of appropriate head height, and other major obstacles to converting that to living space. It's a tearoff and redo, no matter what.

I agree with @User if there isn't enough head height it is a complete roof redo.

Thanks for all the comments, suggestions!

Can you look at doing an addition at ground level?

No, unfortunately based on the layout of the house, we cannot do that.

There is about 10 feet from the ground to the highest point on the roof, so I think there is enough head height.

What about converting the garage as Verbo mentioned and adding a garage or carport in front?

@rockybird great idea but unfortunately i live in Minnesota and due to the amount of snow we get here, a garage is much needed! Also, the HOA won’t approve a carport.

@User correction there are 10 feet from the FLOOR of the attic to the highest point on the roof.