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Help! I don't know mortar from stucco, from cement, from...

Posted by toolbabe (My Page) on
Thu, May 6, 10 at 15:55

I should have paid more attention to "This Old House" when I had the chance...

We had to have the walls of an entire wing of our house redone which meant removing the existing mortar, cement, or stucco... parging. Now we have to put an equivalent sparging back on. We are in a historical zone which means that we have to finish the house with the same material (or its modern equivalent) and in the same colour as what we took off.

Problem is, I don't even know what to call the stuff I took off.

It was some sort of chalky material, probably a lime based stucco that had been applied over a thin coat of mortar or cement, on a metal mesh fastened to the wood planking of the house frame. It had been painted several time, but had cracked, and water had seeped in behind it causing oodles of problems that cost oodles of hard earned to fix.

I don't want to ever have to face the same problems. And I don't want to have to paint the darn thing either.

Acrylic is out of the question - not a "noble" material we are told by the city hall folks. Which leaves me with mortar? cement? and what about the stuff sold as stucco mix?

Also, we must match the former cream yellow colour of the former parging. If we use a cement based product, which is typically grey to begin with, we cannot reproduce the former colour and I'll have to spend time painting rather than sailing. I am told there is such a thing as a white portland based cement which can be tinted to mix just about every colour under the sun, but I can't find any technical data on it.

I should add that this house is over 100 years old and sits near a river where it gets plenty of wind, hot and humid in the Summer, and really, really cold in the Winter. The house is masonry framed except for this particular section which is wood framed and covered (least it was) with some form of cement or mortar or stucco parging.

Also, this won't be a DIY job. Unfortunately, none of the tradesmen we have interviewed has given us a straight or even identical response. The front runner is suggesting some sort of cement which will be shot onto the wall. He suggests to install metal mesh fastened directly onto the wall, with no gap between the wall and the mesh. This raises all kinds of alarms for me. I would think some sort of gap is needed to ensure that the water which will inevitably get in has a way down and out rather than to impregnate the wall and cause mildew or worse.

Right now, there are nailed in 1x 1/2 running vertically every 12" the full length of the walls, over the Typar house wrap. I'd either have to remove them (and cover the nail holes?) or add more to reduce the gap in between so that the mortar won't scallop.

So I am turning to your collective experience and wisdom.

Any thought or suggestions?

Follow-Up Postings:

RE: Help! I don't know mortar from stucco, from cement, from...

Here's a link to Virginia Lime Works, who sell authentic lime cements, stuccoes, and wash/color coats for masonry.
It's as authentic as it gets for recreating old masonry and plaster finishes. We used their products extensively on a restoration project last year, and were satisfied. So was the Historic Resources Commission.
If the stucco is on wire lath, it's probably 100 years old at most.
The wire lath would be fastened over tarpaper.
Lime paint is a great alternative to normal paint for masonry, because lime paint is a masonry product, and is not a waterproof membrane; it breathes and allows water vapor to migrate through without causing peeling.

Here is a link that might be useful: Va. Lime Works

RE: Help! I don't know mortar from stucco, from cement, from...

We had our house re-stuccoed seven years ago. The previous stucco job out of the same stuff you are talking about lasted 75 years in good condition. When we were getting estimates to have it done, local firms would only to the 'modern' stucco but we found a firm who sent a crew over 70 miles one way each day to do the job with the similar material. It took them almost a month, because the stucco had been painted (see Casey's info about normal paint) and they had to install wire lath all over again...because the stucco won't adhere to paint.

As for colour, they used a powdered pigment directly in the stucco so it's uniform to all depths. We are also very satisfied we had it done and done right. It wasn't cheap by any shot, but I have a sinking feeling they didn't make any money off it considering the work involved and the size of the crew. I'll bet somebody's estimator got in deep doo. LOL.

RE: Help! I don't know mortar from stucco, from cement, from...

I'm confused. If you don't know what it was you took off, is the local historical association going to know?

Or do you just need to get their approval for the replacement surface before it is started?

RE: Help! I don't know mortar from stucco, from cement, from...

I have a stucco house - I feel your pain! Sounds like you are in a location that does not have a lot of stucco homes, hence the lack of local expertise.

The trick is finding someone who knows what they are doing. Traditional three coat stucco systems are not hard, just time consuming.

Does your historical society have a reference? Are there are other stucco homes in the area? If so start asking other homeowners who they know who does work. Anyone doing historical stucco would get their supplies thru a concrete supplier and they might have references.

I taught myself how stucco myself after we restored our upstairs dormer. There is a lot of info out there - some parts of the country still do a lot of stuccoing - you just have to dig around. I ended up finding a guy who repairs the stucco for a local large university. He was very helpful - which formula was used on my house, his opinions on stucco wrap vs roofing felt, etc.

Since it sounds like moisture is your nemesis in your area (mine too) so make sure you really research how to keep your substrate dry. (hint: it does not involve spraying the stucco directly onto the sheathing.) Try this link as a starting point.

Chances are that whoever does stucco for you is a smaller company or one man outfit so it might take you a while to find someone. Just make sure you know what you want and how you want it done before you commit to someone.

The following link has a good background on stucco and offers some help in determining what kind of stucco you have.

Here is a link that might be useful: historical stucco

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