The vents into my crawlspace are cut into the wooden siding and I'm not what the correct way to repair/replace them is. All of the examples and products I've seen show the vents in the concrete wall of the foundation, but mine are not. My vents are also smaller than what seems to be normal.

Here's an example of what the vents look like. You can see the wooden frame is rotted. Old rotting foundation vent frame

After removing the vent, you can see a sheet of cardboard that has insulation above it and the crawlspace below. The wooden beam along the bottom is a 2x4 sitting on top of the concrete foundation wall.Vent removed

You can see from this photo that the siding is wood.Wooden siding

All of the replacement vents I found were for sizes like 16" x 8" or 18" x 10". The portion that's cut from the siding is 16 1/14" x 7 1/8" and the inside is 14" x 5 3/4". I didn't feel like cutting a bigger hole, so I tried making my own frame from a 1.5" x 1.5". I'm not a big fan of the result; I can see into the crawlspace pretty easy which makes me wonder if water can get in easily too. The old vents had the horizontal boards slanting downward; I'm wondering if I need those too.My attempt at a new frame

I guess I'm wondering what the best way to tackle this would be. Should I just make new frames similar to originals? Should I cut bigger holes and find fancy automatic vents that will fit; if so, how would that work with the siding? Are the horizontal boards slanting downward functional or are they purely cosmetic? I'm in the Seattle area, if that makes a difference.

  • Wow... this has sat for a long time without a good answer! What you've done looks like a great start. I would hope that you added some louvers (horizontal boards slanting down) to help keep the weather out and that you primed and painted the wood. Also, the dimension of 16 1/14" is very unusual! Was that supposed to be 16 1/4" or 16 1/16"? Also, I hope you fixed up that cardboard in there - it looks like it was intended to keep the insulation from sagging out of the joist where it belongs. There are better solutions than that. Please come back and give us an update!
    – FreeMan
    Jun 10, 2020 at 11:54

2 Answers 2


The vents you removed were constructed entirely of 1x2 lumber and could be easily recreated. You'd want to use cedar or pressure-treated lumber for rot-resistance, if not a synthetic.

All cuts are square. Some corrosion-resistant screws, properly piloted and countersunk, would make them solid. Trim-head screws or splitless siding nails would secure them well.

Use a good quality exterior caulk to seal around the outside, then prime and paint.


My house has the same thing I just discovered it for the first time today and it was covered by shingles so I pulled the shingles off and put metal fence piece over it and nailed it and it's holding up as a good vent

  • 1
    Hello, and welcome to Home Improvement. What's a "metal fence piece", and could you add a picture? And, you should probably take our tour so you'll know how best to contribute here. Jan 12, 2020 at 12:57

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