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Will removal of this plastic cause a leakage problem?

Posted by threeapples (My Page) on
Wed, Nov 7, 12 at 21:03

our masons put this sheet of plastic in the mortar above the water table around our house so that the mortar dropping from above didn't get all over the brick. since the house is still not done being bricked this plastic has been there for a few months. will removing it in the spring cause a gap under the mortar to let water creep in? can we squeeze mortar in there somehow to make a tighter seal? any thoughts?

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Follow-Up Postings:

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RE: Will removal of this plastic cause a leakage problem?

Mortar is not waterproof; it's function is to support the bricks and bond them together.

Raking the joints back instead of tooling them encourages water to enter the cavity so obviously the designer was not concerned about excess water in the cavity. If the plastic doesn't go far enough into the brickwork to break the bond, the wall should function as designed.

Make sure the weeps at the bottom of the brickwork and the tops of openings are clear so water can get out. They should be checked once a year.


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RE: Will removal of this plastic cause a leakage problem?

Ok. The mason told us this kind of joint was best to protect against water damage because it compresses the mortar. This is so frustrating! It's hard to know if they know what they're talking about
How do we check to make sure the weep holes are clear?


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RE: Will removal of this plastic cause a leakage problem?

A compressed mortar joint is certainly the best for weather resistance and would have a smooth steel tooled surface instead of being rough like yours. Also, the most weather resistant shape is "concave" instead of "raked" like yours. See the descriptions on Wikipedia linked below.

Brick joints for private residences are usually designed for appearance not weathering.

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Here is a link that might be useful: description of concave and raked joints


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RE: Will removal of this plastic cause a leakage problem?

thanks, that's really helpful. i'm never building another home again and wish i knew this before agreeing to the mortar joint we have.


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RE: Will removal of this plastic cause a leakage problem?

The mortar joint is not so important if the cavity and back-up wall was constructed properly. That is the real weather barrier; the brick acts like a screen.

When building a house, if you are not extremely knowledgeable about design and construction you must put your trust in the designer and builder; second guessing everything is a killer. If you find it difficult to turn the project over to the contractor you should hire a professional to represent you from beginning to end.


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RE: Will removal of this plastic cause a leakage problem?

No matter how you rake mortar joints, they allow water through by capillary action.

Just like every other Portland cement based product.

The drainage plane is BEHIND the brick.

House wrap, tar paper, etc. prevent further penetration of liquid water.


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RE: Will removal of this plastic cause a leakage problem?

While it is true that all mortar joints will allow water to enter the cavity the type of mortar and how the joint is tooled will make a substantial difference in the amount of water that enters the cavity.

Because the escape of water from the cavity depends so much on how clean the cavity is, the type of brick ties and how carefully they were installed, how well the cavity was flashed, and how good the weep holes are, it is best to minimize the amount of water entering the cavity.

There can be no disagreement regarding what kind of joint limits water in the cavity.

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RE: Will removal of this plastic cause a leakage problem?

nice stuff renovator. thanks
for the mini education!


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RE: Will removal of this plastic cause a leakage problem?

Not to derail from the OP but what about a dry stack? Then you don't have to worry about mortar at all but are there other problems if you do that?


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RE: Will removal of this plastic cause a leakage problem?

We were discussing a masonry veneer cavity wall and what kind of mortar reduced water penetration. Leaving the mortar out would not only allow the maximum water penetration, it would be impossible to construct. You may be thinking of a thin-veneer simulated wall cladding adhered to the structure or a site retaining wall.


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