# concrete dust in the crawl space



## anon125 (May 23, 2014)

our crawl is 3 feet high and has a cement floor. 13 years old house. has a gas furnace

why does the floor get covered in fine gritty dust?
can we stop it?
is this the correct forum?

thanks all


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## de-nagorg (Feb 23, 2014)

Unless you live in a hermetically sealed environment you will get dust infiltration through the air gaps in the walls and floors.

Do you get dust on the furniture? It all comes from the same place.

It's just more obvious in the crawl space because no one cleans under there much.


ED


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## anon125 (May 23, 2014)

we suspect it is cement dust
thanks


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## Bud9051 (Nov 11, 2015)

Hi anon,
To reduce the dust you will want to reduce the air infiltration as de-nagorg is suggesting. During cooler weather the cool outside air pushes in through the lower leaks in the house, especially where the house rests on the foundation, and then up through the house and out the higher leaks. Seems obvious until you hear how much air is doing that. On average, your home replaces all of the inside air every 2 to 3 hours. When sealed up tight to slow that down to 4 to 5 hours other problems surface. The target for proper air exchange and a healthy home is "3 hours". And that is what is bringing all of that dust into your crawlspace.

If you undertake some air sealing efforts don't worry about getting it too tight, nearly impossible to seal up an existing home that much. But reducing that leakage will reduce your heating costs and reduce that dust.

Bud


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## Canarywood1 (May 5, 2012)

anon125 said:


> our crawl is 3 feet high and has a cement floor. 13 years old house. has a gas furnace
> 
> why does the floor get covered in fine gritty dust?
> can we stop it?
> ...



If you want to eliminate the dust, you will have to apply a concrete sealer, a silane/siloxane penetrating sealer will work best.


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## anon125 (May 23, 2014)

who knew it was this complicated!
silane/siloxane penetrating sealer will work best. i assume this is to seal the concrete. any idea how long it will stink the house for?

we vacuumed several pounds of the dust out! but the shop vac of course spread the rest all over the crawl space! dust is every where.
suggestions welcome
the locals who vacuum the ducts do not work in crawl spaces any more.
thanks all
PS sealing the house room returns stopped most of it coming upstairs - and close the registers.


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## Bud9051 (Nov 11, 2015)

Why are you concluding that the dust is coming from the concrete floor? To get airborne and make its way upstairs something would need to stir it up, which isn't typical in a crawlspace. Those dust particles are already airborne and coming in with the air leakage. My bet would be, if you sealed that concrete floor perfectly it will again become covered with dust.

Bud


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## anon125 (May 23, 2014)

well it is gritty and heavy!
thanks


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## stick\shift (Mar 23, 2015)

> it is gritty and heavy


So's the dirt in my yard. Still don't know why you're hung up on this coming from the concrete (cement is an ingredient in concrete).


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## de-nagorg (Feb 23, 2014)

If this is coming from the concrete, the concrete is disintegrating way before it's lifetime (13 years). 

So I would be more worried about my foundation integrity.

Likely the foundation and crawlspace floor were poured at the same time, from the same mixture.

ED


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## Canarywood1 (May 5, 2012)

anon125 said:


> who knew it was this complicated!
> silane/siloxane penetrating sealer will work best. i assume this is to seal the concrete. any idea how long it will stink the house for?
> 
> we vacuumed several pounds of the dust out! but the shop vac of course spread the rest all over the crawl space! dust is every where.
> ...



What's complicated about opening a container and rolling the contents on your floor, and if you use the water based sealer, it's low VOC's so very low smell for any length of time.

And by the way,your concrete floor will last many more than 13 years, probably more like in the neighborhood of 50/100 years

Here's a link, i think Sherwin Williams has this.

https://www.rustoleum.com/product-c...trating-silane-siloxane-sealers/sealers- s-20


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## lenaitch (Feb 10, 2014)

I wonder if it is efflorescence?


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## anon125 (May 23, 2014)

Efflorescence is a crystaline deposit on surfaces of masonry, stucco or concrete. It is whitish in appearance, and is sometimes referred to as "whiskers". Efflorescence has been a problem for many years, and is a topic of much controversy. The formation of these salt deposits are not mysteries.

sounds right to me. we had this in our last home as well
thanks all


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