New Concrete Patio/Slab. Have some questions.

We are getting a concrete patio poured with only one side of the patio up against the house. The patio is not going to covered and we are located in Florida if that information is needed.

Do we need to have those rubber like expansion joints (sorry do not know the names of the item) inbetween the house and the patio? Also, should we have a vapor barrier under the patio?

The company doing the work said that we do not need the barrier because it is not under "cover" and we do not need those expansion joints since the other end of the patio is up against the grass.

Thanks,

greg

 

Yes, it does matter where you are located. I would definitely install a vapor barrier under the slab whether it is covered or not to reduce sweating. The slab will slip on its own, so even though it is a good idea to have an expansion joint against the building, it probably won't be disadvantageous not to have one. Now, what you didn't tell us is how big this slab will be, nor how thick they plan on pouring it, and if they plan on doing an edge footing or not. What do they plan on using for internal support...rebar or fence?

 

The expansion joint is preferred, especially in a freeze climate where you will get some heaving in winter. It would act as a shock absorber to keep the edge of the concrete from chipping. In Florida, I don't guess you would have that problem but I would use it anyway. It's cheap and good insurance.
As to the vapor barrier: I see no reason whatsoever to put one under an exterior patio slab, and would not do it.

 

I agree with the previous posters about the joint.

I would put a vapor barrier under the slab since it is cheap. It may be desireable in the future. People (especially in Florida) have a habit of converting spaces/slabs for a different uses. These uses often have floor coverings/treatments that can best be installed if there is a vapor barrier. You can't go back and add a vapor barrier.

Dick

 

There are many reasons for the expansion joint against the house (and none against), and since the cost is minimal, why woud you not do it? The vapor barrier falls into the same category.