boulder in crawl space

Old 11-02-22, 09:06 PM
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boulder in crawl space

Hello: I bought my house over 30 years ago, and I admit to ignorance in knowing what to consider in buying a house. My house ,which is on a slope,has majority of living space on top level. My problem is entirely with lower level which consists of a huge crawl space with a boulder running through it. It has two smallish windows for ventilation, yet is always in need of the two dehumidifiers.It sits on the top of the slope.One corner will get a very slight amount of water with a hard rain and the boulder in that area darkens from the water running through it. Last owners covered entire crawl (boulder) with thoroseal which is now crumbly and spewing dust.There is also a semi finished room adjacent to the crawl space which is totally above ground and has 4 large windows. Both
spaces always have a musty smell, largely due to the crawlspace with the boulder. This room has old panelinging over the concrete block with a nice pergo like floor.
How do I make the air healthier in both spaces? Can I blast off the thoroseal or just vacuum up the crumbling and dust? Is a giant boulder such as this (which extends beyond the house on both sides ) be left with no covering such as the thoroseal?Is that unhealthy? Maybe the boulder can be sliced flat and a rat slab can be put down? Finally, is there a way that I can seal the adjacent room from the crawl so that it can smell better? thanks in advance. Bonnie
Old 11-03-22, 05:40 AM
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"How do I make the air healthier..."
What does healthier mean air to you? It's not a term with a real definition. So, specifically what do you want to achieve?

Without knowing anything I'd say encapsulate the crawl space. It can be done on the walls/bottom of floor joists or it can be laid directly on the ground.
Old 11-03-22, 07:26 AM
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You need to divert water away from the house outside and put a moisture barrier over the ground in the crawlspace.
Old 11-03-22, 11:22 AM
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Building science, especially in regards to crawlspaces has changed a LOT in the past 30+ years. Houses used to be built with ventilation, but in many cases (especially in the northeast), an encapsulated crawl space is recommended.

Basically as others have said, it's a matter of making the crawl space part of the house. Heavy duty plastic on the floors and walls to keep moisture out. Sealing vents, and adding a bit of heat/cool and/or dehumidification.

You can hire companies to do it, or it's not hard to do it yourself - though working in a tight crawlspace can be a challenge. Some pictures might help the folks here make some better recommendations.

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