Is it okay to build an addition to your home on deck that surrounds it

Idid

I doubt it very much unless your deck has footings large enough to handle a structure. Your local municipality has building codes that will guide you in that regard. I would think the best you could do is to make your deck area a screened porch. I have seen systems (Larson Scenix for example)that make the walls quite easy, but you would have to build a structure for the roof. Palram® Feria Patio Cover is one option for the roof, and they have kits for the sides as well. If you build your own roof support youcan use pvc roof panels that are semi-transparent that should keep you dry!

It has very strong footings. Already had a contractor look at it. It was he who suggested it. But my husband was listening to a DIY show and they said you should never build over a deck. Something to do with the deck boards. That is why I was wondering. If you have sub-flooring on top of it, how can that cause harm?

Judy, there are really too many variables, with the limited information given, to answer yes or no. Start with checking local building codes to see if it's even possible to build. Then I would get the advice of a professional. Ask for bids on the project. Then you will know what you are up against before spending any money.

Decks typically aren't built to carry the weight of an addition of a room being built on top of it. I would get a couple more contractors out to look it over for their opinions and quotes and whether they think they can get a building permit for the addition on top of a deck.