I don’t think the Co2 would be a issue when ‘enclosing’ with screens.
You mentioned a new plat drawing. I noticed the current plat that I see on-line appears to have sheds or other structures that are not on the property any longer. I don’t know when or why the other shed/structures were removed. (The home was recently renovated but covered/enclosed foot print of home it self was increased or not changed from the original design.)
I assume they would count those old structures against our green/structure ratio if we applied for a building permit. How do we address this when inquiring about building a garage or other enclosed structure? Do we submit a new drawing or does the city have to have some one come out? Is there a cost? Trying to find information… but have not yet learned to easily navigate the DC building website