Concrete vs suspended floor over vapor barrier

Question

Our house has a sizable crawl space large enough to use as storage. The space has no slab covering it, but due to radon issues, it does have a vapor barrier to maintain a suction for the radon mitigation unit and to keep radon from seeping into the basement.

In order to use the space for storage, we'll need to put down a floor in order to protect the vapor barrier. Would it be best to poor a concert slab to cover the barrier? Or could we attach brackets to the walls, run joists above the ground and barrier, and just build a wooden floor above that?

Answer 1

There are several issues: 1) effectiveness of slab vrs. framing/crawl space, 2) effort/cost, 3) storage use, 4) future considerations

1) Both systems are effective and are widely used for radon remediation. The key to both systems is sealing the soil area from the living area.

2) The even if the cost is not important, the effort to level the existing soil sufficiently to pour a slab is tremendous.

3) The most important factor may be what is going to be stored. If you are storing Christmas decorations, then that load is minimal (estimated at 30 lbs. per square foot) and wood framing may be appropriate. However, if you’re storing stacks of books, (estimated at 150 - 200 lbs. per square foot) a concrete slab is more appropriate, which will easily support 500 - 1,000 lbs. per square foot. A wood framing system will support 200 lbs. per square foot, but the additional framing, footings, etc. need to be included now not later.

4) If you’re not sure what the space will be used for in the future, I’d definitely recommend a wood framing system with a small crawl space so you could add electrical wiring, plumbing, heating ducts, etc. in the future.

Answer 2

Is your current setup like one pictured on this site?

What do you mean by "best"? Building a subfloor will be more expensive, but you can probably use your current radon system. Pouring concrete will be a cheaper floor option, but it might not be compatible with your radon system, and refitting it would drive the cost up.

The wood floor would be the easiest to do yourself if you know enough about carpentry to build a deck.