# Flattening an old subfloor with sand



## whitesjtaa (May 7, 2012)

I am installing new hardwood over an old 6 inch pine subfloor in a 112 year old house. The subfloor has about a 3/8 inch sag in a couple places and I'd rather not tear it up to shim the floor joists. To do so would require moving a radiator and removing baseboards (likely causing the need for plaster work).

So, I would like to shore up the two areas (about 12-15 inches by six feet each. If I lay roofing felt to that thickness I have found that it makes noise underfoot when compressed. Has anyone used sand to flatten a subfloor. I had heard years ago that it works well.


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## sunkist (Apr 27, 2012)

the egyptions!, there stuff is still sanding (ha ha) have heard of no complaints with floors, just erosion on the exterior.


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## S.R.E. (Apr 8, 2010)

I have used sand to level a sub-grade quite often. :whistling


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## Metro M & L (Jun 3, 2009)

Use ardex.


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## gideond (May 17, 2007)

I've seen it used once to level a badly sloped slab before a floating engineered wood was laid. It didn't take long before it has started walking out from under the edge on one side of the room. Made a real mess.


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## the rock (Feb 27, 2011)

OH no what ever you do don't talk about a old PROVEN method here on contractor talk! Certain PEOPLE on here would rather debate science all night(no life lol)


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## Groutface (Jan 20, 2011)

the rock said:


> OH no what ever you do don't talk about a old PROVEN method here on contractor talk! Certain PEOPLE on here would rather debate science all night(no life lol)


its a quality forum......science is good


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## Rich D. (Oct 14, 2011)

Ive heard of using sand long ago as a sort of uncouplimg membrane to prevent cracked marble in churches and such.

But. 

I just use ardex feather finish...


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## gideond (May 17, 2007)

Just because something use to be done and worked okay doesn't mean it's the best thing to do. Technology has moved on. Use the proper product for the job.


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## sandshots (Feb 7, 2012)

gideond said:


> Just because something use to be done and worked okay doesn't mean it's the best thing to do. Technology has moved on. Use the proper product for the job.


What is the proper product?


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## Tom Struble (Mar 2, 2007)

qp


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## slowsol (Aug 27, 2005)

I tore out a bathroom floor once that had about a 1/2" of sand, felt, then a good inch of mortar. The tile was solid and held up well. I can't imagine putting wood over it though.


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## Rich D. (Oct 14, 2011)

slowsol said:


> I tore out a bathroom floor once that had about a 1/2" of sand, felt, then a good inch of mortar. The tile was solid and held up well.


Thats the first schulter ditra uncoupling membrane right there.


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