Venting under composite decking on a screened in porch
New house under construction. Initial plan was to have a polished concrete floor on a screened in porch. Concern voiced by a contractor was that the concrete may be slippery if it gets wet. Considering the use of composite decking in lieu of the concrete floor. Initial thoughts were to pour the base, affix pressure treated sleeper 2×2’s with stainless tapcons to the concrete and then lay composite decking across the 2×2’s. Concrete base would be sloped to allow moisture to drain through a weep system. In this fashion, the walls can be built up around the concrete and the composite decking can easily be replaced if it ever fails for any reason since the wall isn’t directly on top of the decking. I understand that there needs to be a ventilation path under the decking boards, but with 2×2’s and a synthetic stone watertable surrounding the porch, how can this be done? Some type of venting system? Even if higher joists were to be laid across the “foundation” that’s currently there instead of a concrete pad, how would you vent it anyway with a stone surround? Attached are pics of the current state of the porch with gravel in place. The wood to the left is for the Morning Room. Also attached is an exterior elevation showing the stone surround and a floor layout of that area.
Please advise if there are ways to accomplish this with composite decking … other than applying some alternative material on top of the concrete to make it slip resistant (ie. Naturestone, etc.)
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