Was thinking of getting a hot tub but wanted to put it on a balcony.
The existing balcony is a concrete slab supported by a column every few feet and then tied in (reinforced) into the concrete wall of the side of the house.
What strength is required to hold up a water capacity of something like:
1,419.53 L (375 USG)

 

Unless you know what's inside the concrete I don't think you can determine the strength of your balcony. I would NOT put a hot tub on your balcony.

 

Unless the balcony was specifically designed for a hot tub to begin with, I would not put a hot tub on it now. Possible to get a structural engineer to look at it, but I would not hold out much hope.

 

8.34 lb/gal x 375 gal = 3128 lbs. plus the weight of the empty hot tub plus the weight of the occupants.

Do not do it.

 

Sorry, the question was more like how is the balcony supposed to be reinforced to support this if I do it in future. I wasn't just going to put one on there and hope
The current balcony is definitely reinforced concrete. ie how is it supposed to be designed to hold weight like this?

 

It doesn't matter the deck is reinforced concrete, it matters how it is tied into the building and what's inside the concrete, such as steel I-beams. You would need an engineer to actually look at it and maybe even find the original blueprints.

Just to throw a number out, a wild guess, if your balcony isn't like 16" thick, I would just forget about it. The 16" thick wouldn't be all concrete, but concrete with beams inside.

 

A wood deck has all it's structure out in the open where it's visible. Concrete has it buried inside where it can't be seen and is difficult to detect or inspect. The problem is that you don't know what is in your concrete for support or reinforcement. So, without expensive testing it's difficult/impossible to know what you have to say how strong it is. Simply saying "reinforced concrete" really doesn't mean anything until you can say specifically how it was constructed.

Find out when your deck was built. Then look up the code requirements for deck construction at that time. That could give you some idea. In generally older structures can be very inadequate by modern standards. 20 years ago decks were built thinking there would only be a few people standing out there. Then comes a party with the deck full of dancing people and it's on the news. Numerous deck collapses have shown many of those older decks did not have a lot of safety margin built into them.

 

What would be the foundation and supporting requirement for a wood deck with hot tub on top? Let's say the concrete was removed and instead a wood decking was put in place with supporting concrete or pillars?

 

I would not build a deck for a hot tub without a framing directly under it with 4 posts extending to properly set footings.

 

If you search online for "reinforcing deck for spa" you will see some diagrams. Many follow Chandler's advice and have another set of posts under the spa in addition to the usual posts you see for a deck. You could span the distance and go without posts underneath but if attempting that I would seek the advice of a Professional Engineer especially regarding the attachment to your house.