Adding another topcoat of plaster
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Bailey House



Joined: 23 Sep 2007
Posts: 22
Location: Oklahoma

PostPosted: Tue Jan 11, 2011 11:59 pm    Post subject: Adding another topcoat of plaster Reply with quote

Our 1902 house has most of the original plaster in it and it is in good shape. However the wall is really wavy (original plaster guy didn't lay it flat or something), and it is also nicked really bad from us trying to remove wall paper.

I was planning on skim coating the walls with new plaster, leaving the old on there, and just adding a new outer coat. However, I talked with a technician at USG and he didn't know what kind of product they had that would stick to the existing plaster. I was planning on using their bonding agent and then applying a coat of either finishing plaster or gauging plaster, but after reading what thier tech bulletins said I wasn't so sure.

What do you guys recommend? How do you do it without taking the wall down to the laths?

Thanks
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rncx



Joined: 21 Jun 2008
Posts: 660
Location: Little Rock, AR

PostPosted: Wed Jan 26, 2011 2:45 am    Post subject: Reply with quote

my plasterer uses USG "diamond finish".

http://www.usg.com/diamond-veneer-finish.html

as for the bonder, they use regular ole quickcrete concrete bonder from home depot. they say that stuff is all the same, basically.

fwiw, it takes know-how to plaster a finish coat on a wall. there's more to it than putting it up there evenly. i'm a firm believer in the principle that the vast majority of work around a house can be DIY with good results, even to the extent of building doors/windows/furniture.

but plaster does take a skilled hand. it's the one architectural detail that will always be truly 'hand made'. i don't think there's any shame in hiring that work out.

as for wavy, it's gonna be wavy here and there. there's not a whole lot you can do about that. see point above about 'hand made'. these guys are just eyeballing it and holding up a board for a straight edge here and there to check as they go. it's not an exact science.

if you could look inside the wall you'd find crooked rough studs too. the plasterer's job is to make it look straight, not necessarily be straight.
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johnleeke
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Joined: 20 Aug 2004
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PostPosted: Wed Jan 26, 2011 10:12 am    Post subject: Reply with quote

When skim coating new over old, you have to consider the long-term expansion and shrinkage of both the old and the new. If they are different enough there may be failures. The stress of the differential movement can cause adhesion failure or cracks and rifts in the skim coat. Plasterers with decades of experience might know enough about differential expansion and about their materials to keep the skim coat from peeling off.

Why do you think a skim coat is needed?

Couldn't you just repair your dings and call it good?

Some plaster walls were not meant to be the finished surface. Often plaster was left rough or wavy because they intended it to be covered with stretched linen backer cloth and wallpaper. It sounds like this is the case with yours. If you are going to re-paper then you may not need to improve the surface.

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rncx



Joined: 21 Jun 2008
Posts: 660
Location: Little Rock, AR

PostPosted: Wed Jan 26, 2011 4:14 pm    Post subject: Reply with quote

i'd be interested in hearing another plasterer's opinion on the matter myself.

from what my guys told me, in their opinion tearing out and re-filling cracks properly is alot more important than matching the material. they say they prefer the newer plaster mixtures to the older lime mixtures because the newer mixes are less prone to decay and get brittle over time, so they resist cracking better in the first place.

i've had work done from them over two years on different rooms, and in the first round of work from a couple of years back, in their defense, has only had one minor re-cracking, and it was in a very rough water damaged spot. they touched it up again this last time they were out but it was an imperceptible crack, i hadn't even noticed it, the plasterer remembered how rough that spot was and said he checked it himself to see if it was holding up and noticed a couple of ~1 inch hairline cracks just around the water damaged spots.

fwiw this is just a debate about plaster on the existing base coat. if it were plastered directly to a masonry wall, i think they all agree that matching the material is much more critical due to variances in moisture transfer and hardness. this work i'm talking about is just refinishing an already stable and solid existing basecoat, after scraping most of the old loose finish coat free.
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MohrJax



Joined: 06 Nov 2007
Posts: 23
Location: Jacksonville, Florida

PostPosted: Thu Jan 27, 2011 9:26 pm    Post subject: Reply with quote

as John stated, couldnt you just repair the dings? are you going to paint the walls? or leave "natural"......not sure I would skim it, im not a plasterer but have witness too many skim coats just peel off...
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Angel Corrales

MOHR Historic Restoration Company
1308 Dancy Street
Jacksonville, Florida 32205
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Randall



Joined: 06 Aug 2009
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Location: Colorado

PostPosted: Fri Jan 28, 2011 8:59 am    Post subject: Reply with quote

Hi, it all come down finding the right plasterer with the knowledge and know how. I am including a picture of a church interior that had many cracks, holes, etc. All areas were patched to match.

The picture included is the property of RM Design & Construction[/img]

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Randall Marder
RM Design & Construction Inc.
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http://www.rmdesignconst.com
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Randall



Joined: 06 Aug 2009
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PostPosted: Fri Jan 28, 2011 9:00 am    Post subject: Reply with quote

how do you add images??
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Randall Marder
RM Design & Construction Inc.
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johnleeke
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Joined: 20 Aug 2004
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Location: Portland, Maine, USA

PostPosted: Fri Jan 28, 2011 7:48 pm    Post subject: Reply with quote

You can add an image to a message by attaching it to the message while you are writing it. Instructions for adding attachments:

http://historichomeworks.com/forum/faq.php#39

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Bailey House



Joined: 23 Sep 2007
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Location: Oklahoma

PostPosted: Fri Jan 28, 2011 11:39 pm    Post subject: Reply with quote

Thanks for all the replies.

Most of the dings, I was just going to patch, however there are areas that have big holes and chunks of the existing topcoat falling off. These are the areas that I want to topcoat. The drywall mud does not have the same consistency of the plaster, or the same hardness. I think it will work beneath wallpaper, but we don't like wall paper, nor do we like heavy texture, so we were going to keep the walls smooth and paint them.

I have a guy that knows how to plaster, but I want to make sure he uses the right material. He is supposed to teach me, and I will get to work on the less noticeable areas.

So is the topcoat usually a lime plaster? I am pretty sure my base coat is gypsum, do to the fact that it is brown, and does not hold up well to moisture.
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Randall



Joined: 06 Aug 2009
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Location: Colorado

PostPosted: Sat Jan 29, 2011 8:40 am    Post subject: Reply with quote

I give it a try.

This is a picture of the Ruth Memorial Chapel built around the 1890s. The building stood empty for years. The interior was a mess, with crack and damage plaster walls broken glass, etc. After restoration to the entire interior: windows, flooring, woodwork, etc. you can see the rebirth



Ruth-Memorial-Restored-Inte.gif
 Description:
 Filesize:  3.57 MB
 Viewed:  652 Time(s)

Ruth-Memorial-Restored-Inte.gif



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Randall Marder
RM Design & Construction Inc.
37 years experience in historic preservation
http://www.rmdesignconst.com


Last edited by Randall on Sat Jan 29, 2011 8:59 am; edited 1 time in total
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Randall



Joined: 06 Aug 2009
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PostPosted: Sat Jan 29, 2011 8:55 am    Post subject: Reply with quote

when I change the picture from a very low bit jpeg file to a even lower gif file it took.
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Randall Marder
RM Design & Construction Inc.
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johnleeke
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Joined: 20 Aug 2004
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PostPosted: Sat Jan 29, 2011 9:20 am    Post subject: Reply with quote

Randall:

Thanks for uploading the photo of the church.

Quote:
when I change the picture from a very low bit jpeg file to a even lower gif file it took.


It did not upload at first because the file size was truly huge. The file you attached is 3.57 MB, which is still a very large file. While the forum system will take it, just a few of these will use up too much memory and bog down the forum system.

Photo file size from .01 MB (10 KB) to .1 MB (100KB) is more appropriate because it takes up much less memory space and shows all the details on everyone's screen just fine.

I don't want to discourage you from uploading photos, in fact it's encouraged, but see if you can figure out a way to get your file size down by at least ten fold. Usually graphics or photo handling programs have a way to do this. (keep in mind, I have to pay for the memory storage space for all of this)

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by hammer and hand great works do stand
by pen and thought best words are wrought
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Randall



Joined: 06 Aug 2009
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Location: Colorado

PostPosted: Sat Jan 29, 2011 9:24 am    Post subject: Reply with quote

Opps sorry I thought it was much lower than megs. I can delete it if you want. I do not want to overload the system
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Randall Marder
RM Design & Construction Inc.
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http://www.rmdesignconst.com
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johnleeke
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PostPosted: Sat Jan 29, 2011 12:04 pm    Post subject: Reply with quote

If you can make a smaller sized file, try posting it. I'll clean up any duplicates.
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Randall



Joined: 06 Aug 2009
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Location: Colorado

PostPosted: Sat Jan 29, 2011 12:39 pm    Post subject: Reply with quote

I tried various test using photoshop this is the smallest I got it. Let me know if this is okay. If not I have to shot my picture with less resolution or find a free software, online, that can compress my photos even smaller without losing detail


Ruth Memorial Restored Interiors adj 3.jpg
 Description:
 Filesize:  26.61 KB
 Viewed:  665 Time(s)

Ruth Memorial Restored Interiors adj 3.jpg



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Randall Marder
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