I approach inspecting a townhome just like inspecting a single family residence. I do not distinguish between what the HOA is responsible for versus what the home owner is responsible for. The exterior will be inspected just like a single family home beginning with roof, flashing, walls, stoops, steps, decks, patios, driveways, railings, etc. Afterall, whatever goes on on the outside, could affect the inside and could result in a safety concern for the client.
In my reporting system, there is one additional item I comment on is that of "Firewall Separation in Attic and Garage"
The first picture below illustrates a portion of a townhome unit's firewall in an attic that is totally sealed off to provide 1 hour of fire protection on both sides. For example, if there is a middle located townhome with adjacent units on either side, you will have 1 hour of fire separation at each side.
For older units with parapet walls using masonry blocks known as concrete masonry units or "CMU's", they provide a total of 4 hours of fire rating. You will see this on older complexes where there is a physical wall that extends on upwards (forming the parapet or "fortress") of approximately 3' above the roof line. On newer construction where a gypsum product is installed instead of CMU's with parapets, the underside of the roof must also be covered with 5/8" gypsum that exends from wall out to a distance of 4'.
Many older complexes utilized 5/8" Type X gypsum on walls and either Type X gypsum or fire-retardant-treated "FRT" wood on underside of roof decking to provide fire separation. While inspecting those townhomes, the firewall assembly is often incomplete or breaches have taken place. Personnel who have accessed attic areas often knock out a portion of the wall or there are missing panels. (Pictures 2 & 3) Tape between seams are often missing or loose. Penetrations of cables also produces a breach, allowing for faster spread of fire. Proper separation buys valuable time and provides important protection. In the metro Atlanta area, particularly in Dekalb County, it's common to hear of apartment fires that spread like wildfire because there was no firewall protection in place.
If you are in the market to rent an apartment or purchase a townhome or condo, hire a qualified home inspector to get up in the attic for you. It makes good sense to have it inspected for the purpose of safety and peace of mind, even if the property is sold "As Is" and appears to be a steal of a deal!
Well executed fire separation complete with visible sticker:
Holes knocked in firewall and missing panels in firewall: