Does a Parge Coat add Strength to a Wall

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Old 01-29-11, 03:43 PM
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Does a Parge Coat add Strength to a Wall

Just finished parging an inside wall in my basement, top half is brick and bottom half is half old stone/sand/cement mix and the bottom half of the bottom half is dirt (house was built in 1920), using TYPE S Mortar. The wall is structurally sound, in good shape, not crumbling. I just parged it to even out the uneven brick work and rocky bottom half.

It got me wondering ignoring all other variables: Will the parge add strength to the wall helping prevent it from crumbling in the future and help it stay structurally sound?
 

Last edited by wewantutopia; 01-29-11 at 04:41 PM.
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Old 01-29-11, 04:30 PM
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I'm not a mason but would think that while the stucco wouldn't add any structural strength to the wall it should help preserve it from future deterioration. My only concern would be the exterior side - is it in a good shape and sealed to keep moisture from entering the foundation?
 
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Old 01-29-11, 04:42 PM
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The outside foundation is fine. Please ignore all other variables.
 
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Old 01-30-11, 11:30 AM
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Do you want the good news or the bad news?

The Good news is that a parge coat can add strength to the wall. The bad news is that parging an old wall can sometimes destroy it.
 
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Old 01-30-11, 05:08 PM
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Interesting. How could parging destroy an old wall?
 
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Old 01-31-11, 11:55 AM
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The 20's are on the edge of the lime mortar era. If the brick/stone work WAS done with lime mortar, parging it with a non-breathable portland based stucco will trap moisture in the wall, basically dissolving the lime mortar.
 
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Old 01-31-11, 12:42 PM
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Thanks for the replies!

I THINK I am ok then. I'm pretty sure this wall is not original. It is non-structural, the joists sit on an outer wall. The "basement" is a dug-out cellar. There are shelf footings around the perimeter inside. There is also 2 foundation walls: an outer concrete block wall and air gap then a partial brick wall inside (which sits on a concrete then dirt base). The whole "assembly" is over a foot wide. Plus it looks like it has been painted and parged for years in the majority of the rest of the basement.

Just to be sure, is there any low tech low cost test I can perform on the mortar to see if it is lime based? There are randomly removed bricks with mortar on them where wires have been fed etc.
 
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Old 01-31-11, 05:49 PM
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Pour vinegar on the mortar, if it bubbles a lot it is lime mortar.
 
 

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