Hi, I am purchasing a home with a cantilevered balcony, built in 1960. The balcony runs the entire length of the house (42 ft) and is 5 ft wide. The floor of the balcony is covered with plywood which is topped with outdoor carpet. The roof completely overhangs the balcony and the underside of the balcony is also enclosed with plywood. Therefore the joists are pretty well sealed up. My question is... how can I be sure this balcony is safe without being able to see the joists? Could the joists be rotted even though they're sealed up? How would I know? I'm afraid of getting stuck with a huge problem safety-wise and money-wise. Any advice? Would it be difficult to convert the balcony to a larger deck? Thanks.

Are you asking for a way to inspect before you buy, or is it a done deal?
I'd say you have to randomly remove some of the plywood underneath, probably at the ends or where there is the most water draining.
To build a deeper 42' deck will be expensive, lots of dumpster debris and you will need footings and piers below the frost line (42" where I live), every X feet apart as required by depth and code in your area.
Consider a section of deeper deck, not the whole 42'?

Yes, a way to inspect before buying as we're still in the negotiation stage.

If we built a deck it wouldn't have to be the entire 42 ft, but how would you get rid of the cantilevered joists in order to apply a ledger board?

Thanks.

The size of new deck would determine if u have to remove the cantilever beams. If the existing beams are large enough, u slide new beams along side and nail them together. Be sure new beams sit on the house plate. U will have to put blocking to close off opening to house.

Put girder about 2' back from outside edge of deck to support the new beams.

Chuck

I wouldn't call joists covered with plywood for 50+ years "sealed up" exactly. You are very wise to investigate and fully inspect this situation before you make any commitment.
If there is deterioration it could also extend to the inside of the buidling.
The cost to properly inspect the structure may be more than you want to invest, unless the house and land are really appealing to you for other important reasons.
Personally, with generally so many houses being available in most areas, I would keep looking and if I wanted a balcony or deck-just start from scratch with another house and build something that I knew would last.