# Ontario Crawl Space Encapsulation 2026: Why Vented Crawl Spaces Fail and Full Encapsulation Costs

**URL:** <https://home.renovation.reviews/t/ontario-crawl-space-encapsulation-2026-why-vented-crawl-spaces-fail-and-full-encapsulation-costs/46945>\
**Category:** Ontario\
**Created:** [April 26, 2026, 7:48pm UTC](https://home.renovation.reviews/t/ontario-crawl-space-encapsulation-2026-why-vented-crawl-spaces-fail-and-full-encapsulation-costs/46945 "2026-04-26T19:48:55Z")\
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**Author:** ![system](https://home.renovation.reviews/user_avatar/home.renovation.reviews/system/32/77_2.png) [@system](https://home.renovation.reviews/u/system)\
**Post date:** [April 26, 2026, 7:48pm UTC](https://home.renovation.reviews/t/ontario-crawl-space-encapsulation-2026-why-vented-crawl-spaces-fail-and-full-encapsulation-costs/46945/1 "2026-04-26T19:48:55Z")

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Vented crawl spaces are a known building science failure in Ontario’s climate. Encapsulation is the proven solution. Here’s the 2026 guide.

**Why vented crawl spaces fail in Ontario:**  
Warm, humid summer air enters the vented crawl space and condenses on the cooler floor joists and subfloor – depositing moisture exactly where you don’t want it. Research established 20+ years ago that sealed, conditioned crawl spaces outperform vented ones in humid continental climates.

**Full encapsulation process:**

1. Seal all foundation vents permanently
2. Install heavy-duty poly liner (minimum 10 mil, preferably 20 mil) on ground and up walls
3. Tape all seams and wall connections
4. Rigid insulation on interior foundation walls
5. Dehumidifier or conditioned air connection
6. Seal access hatch to same standard

**Critical:** Remediate any existing mould before installing liner – encapsulation seals problems inside the structure. Surface mould on wood: treat with borate solution (Tim-bor, Boracare). Structurally compromised joists: sister or replace first.

**GTA cost ranges (2026):**

| Scope | Cost |
| --- | --- |
| Basic encapsulation, liner + vent sealing (600-800 sq ft) | $3,000-$6,000 |
| Full encapsulation with wall insulation and dehumidifier | $8,000-$16,000 |
| Mould remediation (if needed) | +$1,500-$5,000 |

Energy savings: typically $400-$800/year in reduced heating costs.

_Crawl space and moisture questions at [home.renovation.reviews](https://home.renovation.reviews)_