Best insulated crawl space vent covers

Top pick: the Recessed Crawl Space Vent Cover (shallow depth encapsulation seal) — it sits inside the opening rather than over it, so it seals the vent without bulging past the foundation wall, and it's the best-rated of the recessed styles here. Good for most 8" x 16" vents.

Who the others suit:

• Standard-depth recessed cover — same idea with a deeper cup, for vents set further back in the block.
• Frost King foam plug — the cheap, quick fix for a few vents you only block in winter; not a permanent seal.
• Master Flow aluminum cover — a metal, louvered cover when you want airflow control rather than a solid plug.
• ATMOX internal-mount plates — for a full encapsulation job, mounted from inside the crawl space.
• Multi-packs and damper/screen covers — best when you're doing a whole house at once.

Measure your opening first: most of these fit 8" x 16", and a few are sized differently.