1950s house plaster ruined by water

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Old 05-26-17, 03:32 PM
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Unhappy 1950s house plaster ruined by water

My house was built in the mid 50s. The outside is brick veneer over cinder-block walls. Inside, exterior walls seem to be some sort of finishing plaster; over heavily aggregated something—like a sand mix or even cement, on a wire lathe, and more of that kind of material behind it. I have no idea what it is.

There was water damage from a leaking roof. Roof has been fixed. I decided to try to repair blistered paint and ran into the damaged “plaster.”

Where the water has come through there is a deep, horizontal, crack. The aggregate material (plaster?) there is crumbly. Scrape it and it breaks into powder. Tapping along the wall, the sound goes form solid ping, to hollow.

You can see from the picture where it completely crumbled apart where I tapped it.

Can anyone help identify what this stuff is and tell me if/how I can repair it?

Thank you,
Bob
 
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Old 05-27-17, 04:16 AM
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Welcome to the forums!

That is called the brown coat. IMO the easiest way to repair it is with a setting compound like Durabond or EasySand. If the damage is extensive with a lot being removed you can fill the gap with a piece of drywall and then apply the hot mud.
 
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Old 05-27-17, 11:59 AM
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Is what you show all there is or is more loose that you have not exposed. The horizontal crack is where the lath not lathe joins the probably gypsum lath on the ceiling to e wall.it is probably rusted out. If that is all you need to fix then use settingjointcompound. If this will be a larger area the take off all that comes off easily with a scraper not a hammer and chisel then
Post new pictures. This is not a complicated fix. There will be some mess involved in tearing out the damaged plaster. Remember water runs down so there may be Mose loose, that is unbounded not about to fall off necessarily plaster that should come off so you do all the needed repair at once.
 
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Old 05-27-17, 12:02 PM
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If you probe where thedeep crack is how deep is the plaster. Before you hit the block? I have seen foam insulation on the inside of block walls then plaster over that insures of your vintage.
 
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Old 05-27-17, 12:40 PM
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from the inside wall to the rusted lath is about an inch. the white plaster is about 1/4, then 3/4 in of brown coat. In looking behind the lath it appears to be cinder block. the walls are like ice during the winter, so I doubt there is any insulation.
 
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Old 05-27-17, 01:03 PM
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Thank you everyone.
this is very helpful.

I think I can make the repair if the damage is not too extensive.
the spot in the picture is the worst, at least from looking at the wall from the room. that spot is where water was actually pouring in and running down the wall during a rain storm.

However, there are small spots of blistering paint about 10 feet to each side of what the picture shows. It is along the same horizontal line, about 8 inches below the ceiling.

I was thinking the disintegrating material behind the white plaster is some sort of brown coat.

All the plaster I have is either patching plaster or POP.

I do have some acrylic cement (vinyl concrete patch). Could I use that in a 1:3 mix (by volume or weight?) with sand as a brown coat?

Or are the durabond and easysand premixed brown coats?

I just hope I don't keep finding more and more damage as I go along.
Lightly touching the brown coat with my putty knife, in the area of the picture, cause it to turn to dust and sand. As I get further away from the damage shown, the white plaster seems to be intact, except for the few places of blistering paint which I have to explore, but I have no idea what the brown coat beneath it is like.

so, I guess, I need to either make or get something to use for the brown coat. remove all the old brown coat that is no longer solid--which may be a lot--
put on some sort of adhesive material to get the new mud to stick to the old?
and since the brown coat is 3/4 inch thick, only go 1/4 inch at a time?

Hot mud was mentioned. Is that a chemical I can add to the brown coat, as well as my plaster,--maybe add to my vinyl concrete patch cement + sand, that will speed up the dry time. Or do I have to apply no more than 1/4 inch at a time. --From the looks of what they did, I can see only one, 3/4 inch layer of brown coat.

btw--You are great. THANK YOU (yes, shouting for happiness for the help you give me. )
 

Last edited by bobt98; 05-27-17 at 01:46 PM. Reason: add info
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Old 05-27-17, 02:24 PM
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Durabond and EasySand are setting compounds. It's a powder that you mix with water and has a preset work or hardening time. It is often referred to as hot mud [it generates heat while it's curing] It dries chemically while ready mix joint compound dries through evaporation. For many of us it's easier to use a setting compound when repairing plaster.

Tightcoat is a plaster expert, if you follow his advice you won't go wrong
 
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Old 05-27-17, 03:32 PM
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So far tightcoat has asked more questions than given advice.
It is very common for water damaged brown coat to fail when the lime based finish coat is still or at least looks sound. That hollow sound you mentioned in the first post is the sound that means the brown coat has failed or at least the bond with the block has failed. I know you don't want to go through the mess and the work of removing all that is loose but you really should. Then you can do the repairs. If you take off all that is loose down to the block and if it is more than a couple square feet you would be better off repairing it with plaster. You can probably get Gypsolite or StructoLite plaster locally. It is pretty friendly to work with and you can fill this out in one coat then finish it smooth with EasySand or another brand of setting compound,

Brown coat is gypsum plaster of a different formula from patching plaster. Patching plaster will work but you have to move fast I am not familiar with POP. Vinyl concrete patch does not bond well to gypsum. It would probably work if you give the joint a couple of coats of bonding agent. The best is Weld Crete by Larsens Products. Plaster Weld will probably work as well since this is indoors. There are other brands and more commonly available is Qucikcrete Conmcrete Bond. Don't confuse their bonding agent with their Concrete Fortifier. They look the same and the jugs look much the same they are different products. No matter what you do it is a imperative that you use a bonding agent.
ALSO GET EVERYTHING OFF THAT IS LOOSE OR CRUMBLY OR SOFT OR UNBONDED. And whatever you use to do the repair make sure you do not get it higher or fuller than the surrounding because when it is all done you are probably still going to want to smooth it all over with joint compound.
Oh, I just figured out POP = plaster of Paris. Not the best choice it works even faster than the patching plaster Work fast.
I could make a treatise on plaster but what the different kinds are and their special uses don't matter.
First get of all that you think should come off then put up a picture and we can tell you what we think are your best options.
We don't all agree on this. It has to do with what we know and are used to using.
You have options.
 
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Old 05-27-17, 05:41 PM
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Thank for the great advice and suggestions.

I haven't been able to find either Gypsolite or StructoLite plaster locally. I did find I could order Structo-Lite, if I order 40 bags. Ha! I don't really want to tear down my entire wall for a small repair, but reading about Sructo, it seems to be the stuff that would best match what is there. Perhaps I could still use my Quikcrete vinyl concrete patch + sand, with a bonding agent?

I did see some other plasters/brands that say "foundation plaster." would this be the same thing--although, maybe not as good? I'm not sure how I will handle an 80# sack of plaster, though.

The easiest way may be the setting compounds--although, they do say "joint compound," and I will be using it against metal lath and old base/brown coat. I am a little worried about the setting compounds binding properly to the old base/brown coat. I read that the modern plasters may not stick well to the old stuff. If I go with durabond, would I need to use a bonding agent?

Exploring a bit more, the hollow sound, when I tap on the wall with my fist, runs nearly 15 feet by 4-6 inches square, with a few solid places here and there. So, it is not a wide area but a long one. It will be tough to work new material in. The area is a bit small for a trowel.

I also notice that someone tried to repair the horizontal crack many years ago with white plaster and painted over it. Maybe it is that which has come un-bonded and not the actual base coat (I know--wishful thinking).

My thoughts are I would like to use real plaster, with aggregate in it, to match what is there, then use durabond on top of that with a finish coat on top. But maybe durabond with easy sand on top will do the job just as well?

--my neighbor is a General contractor. His suggestion is to tear down the house and start over~!

Thank you, everyone, for your good help.
 
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Old 05-27-17, 08:58 PM
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A couple of things. Bonding agent never hurts. Better than your fist to find the loose spots is something harder. A screw driver handle or a light hammer tapped gently. You will hear th difference. I don't know about your concrete patch with sand. It might already have sand, albeit fine sand.

I also don't Know what foundation plaster means. Gypsum plaster will work for you better than Portland cement plaster. Gypsum plaster sets once and can't be .retempered. Portland cement plaster can usually be retempered. If it says on e bag it can't be remixed and if it is white or whitis grey it is probably gypsum. But Portland can also be made white.
If you're u go the setting John not compound route it will bond especially if you use a bonding agent. It does not have the body of plaster so you can't build it out in one coat.

As far as what tool to use, use what works. Don't build your material beyond flush with the existing.
 
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Old 05-27-17, 09:13 PM
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I did a little looking. Foundation plaster must be a Portland cement product. I will work for you but not as a gypsum product. gypsum bonds well to Portland cement bases but Portland cement materials do not bond well to gypsum. Bonding agents help.
 
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Old 05-27-17, 10:24 PM
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thanks. Big box stores on web, labels Structo-Lite as "USG 50.5-lb Bag Foundation Plaster." There is also a Quckrete product labeled "foundation" plaster on the bag. The Structo web site calls their plaster, "USG Structo-Lite® Basecoat Plaster." It is a Gypsum product with aggregate. I was thinking about using it since it seems most like what is on the wall. However, the store here does not have Structo, but only has the Quikrete. --But, just checked and the Quikrete Foundation Plaster is a portland cement product. Now I am totally confused. will have to do some thinking about this.

Probably best way to go is the joint compound--durabond, with bonding agent, embedded fiberglass, and top coat of easy sand?

More information as I tear into the wall:
What I thought at first was as horizontal crack, now appears to be a seam between brown coats, one coming down from the ceiling, attached to mesh, and the other coming up from the wall--no visible mesh, laid directly on cinder block. The seam seems to run the perimeter of the outside walls.

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Evidently, they did not join the two together when construction was done?
Should I try to bond the two (force durabond in the gap) or just build back up the damaged base coats?

And, more on where the brown coat has failed:
It seems to be intact except for the front 1/4 inch--between it and the two coats of white plaster. There, it is essentially a 1/4 inch of dust. I believe that is what is making the hollow sound--nothing solid between the white coats and the brown coats.

It is that way, extending about 10 feet, along the seam, in both directions from the center of the picture.

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I don't know if I am up to tearing out and rebuilding 20 foot of brown coat. Only fix the most severely damaged area that I have exposed, so far.
Is there any tip on how to build out the damaged brown coat so it is at the same level as the undamaged ? About all I can think of is to tape a string between the good and try to build up to that level.
 
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Old 05-28-17, 04:02 AM
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Unless you have areas wider than shown in the pics a drywall knife should be all you need to keep the repair level. Drywall knifes come up to 12" wide. Some prefer to use trowels but I never have.

I've always made these types of repairs with Durabond as I'm not familiar with plaster products. I usually only primed the areas to be patched if they were dusty. Tightcoat makes these repairs for a living, I've just done them to facilitate a paint job.
 
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Old 05-28-17, 08:49 PM
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I don't know who names and writes descriptions of products in the big box chains, but they don't a.ways get it right. Maybe something else carries the name but I doubt it. furthermore I have never heard of foundation plaster. It must be a Utah or mountain states thing. Gypsum plaster certainly will not stand up to the exposed to th exterior elements and is not a good choice for interior application it foundation walls if where will ever be moisture infiltration and in enough years that is likely.
You asked how to get the new surface even with the Old. Spread on whatever material you use and then use the existing surface as screeds to shave off the excess material. Use a sawing motion and hold whatever tool you use, a straight stick, or a wide knife or a trowel edge and it should be even. Hold the straightedge whatever it is at an angle not straight up and down but at an angle to he center of the earth, or th floor and ceIling.
Whatever you do don't get it too full. You can always add more material.

Now I have never done this. But i have heard that you can sort or reconsolidate a softened brown coat. Paint it with something like acryl 60. I don't know if that product is still made but something like it is. Thing is acrylic is a bond breaker so after you use that and it is dry you will still need to apply a bonding agent before whatever you use for the repair.
 
 

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