We have covered porch at the corner of our house. 2 sides open / 2 sides against the house.
I’m ripping out the old floor and putting wood flooring down, not T&G, just treated 5/4. Total area is roughly 11’x25′ Currently there are no foundation vents. Should I worry about not enough air flow below the boards?; they will get wet in heavy rain and wind.
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What is your foundation?
Full screen or knee wall?
How much overhang (single story roof above the porch)?
Gutters?
Generally I would not see a problem venting the area.
Necessary? Maybe.
Screen it so no small animals make a home.
Block with brick veneer. the long dimension is a gable end, with a pretty high gable peak, still has about 3' overhang.
the picture is the under construction view, many yrs ago.
What if any fill behind block?
Condition of the old floor, joists?
Did you fill any cores in those block?
Cutting in foundation vents won’t be easy. I suppose you can locate and drill through from the backside……..or the outside to find the most pleasing location…..
What do you have in mind for the finished look (vents)?
And I suppose you might be thinking venting in the joist box, so not bad at all.
I’m glad it’s you not me.
Should not be any filled cores in the blocks and there's not much fill behind them. The entire floor joist system will be new. I suppose I could use round vents? might be easier to core drill several smallish vents. maybe?
What are the joists made of? If they are not treated, you are wise to consider ventilation. If you were to close this space in, the code would require venting in the walls below the floor.
Did the original deck boards rot?
One thing to consider is providing venting via the deck.
You could drop a couple floor vents in. You could also plan for a trap door for inspection access, and for when some valuable item falls between the cracks in the deck boards.
treated 5/4 decking may be sold green, but in any case, will shrink and swell with the seasons. If you will space on install, you might get enough air between the deck boards.
Mike, all the framing will be treated. I like the idea of a hatch. I'd usually allow 10d spacing between the boards on install. Shrinkage will open it up to at least 1/4" I've noticed. Not an issue for me. I guess my real fear is rain blowing in, soaking the ground beneath, and not having the ventilation needed to dry properly.
I would think the gaps would mostly be enough. (but you someday might decide to scrub those boards before adding some stain..or dump a cooler, or a freak blizzard could blow a foot of snow in...)
The trap door would let you drop a fan if you thought you needed it for a while.
what is under the deck? Some landscape fabric and rocks might be worth adding to keep stuff from growing. A good idea to adjust the soil level so it runs downhill to the outside, and verify this is above the soil level outside (which should run away from the house)
If you installed a non-porous sheet under and up the walls, you could end up with a swimming pool and issues.
I would expect liquid water to migrate though the block foundation to the surrounding soil. Hopefully any below-grade sensitive parts of the house are protected by waterproofing and perimeter drains.
Then the air has only to handle residual moisture after the liquid drains into the soil structure.
I'm in the deep south so blizzard would be real freaky. right now there's maybe a foot or so(?) of fist sized rock and/or chunks of concrete on top of soil. (the concrete is the stuff you get when they use one of those big machines to grind up big chunks of concrete for disposal) It's south facing so it has that going for it; gets lots of drying sun in the summer.