Efflorescence on plaster bathroom wall?

**Heather** · 05-21-2013, 05:16 PM

Hi all,

I discovered some rather nasty looking white growth on the middle/bottom of one wall in my bathroom near the shower. This is an old home with plaster walls. The "growths" are hard to the touch and some appear on the surface while others appear to have burst forth from under the paint. From looking around your website (and others), it seems like this may be efflorescence. I pulled some off with my fingers and it appeared to crumble into dust (along with paint!), and it also seems to dissolve in water. I couldn't get a big enough chunk to put in a glass of water, but putting a wet Q-tip against one of the spots made it dissolve fairly easily. We have great ventilation in this bathroom, although I'm sure it still gets nice and humid in there.

So, do you all think it is efflorescence, or could it be something else? Thanks for your help!

bathroom wall-2.JPG bathroom wall.JPG

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**Billy Stephens** · 05-21-2013, 05:39 PM

Originally Posted by Heather

Hi all,

I discovered some rather nasty looking white growth on the middle/bottom of one wall in my bathroom near the shower. This is an old home with plaster walls. The "growths" are hard to the touch and some appear on the surface while others appear to have burst forth from under the paint. From looking around your website (and others), it seems like this may be efflorescence. I pulled some off with my fingers and it appeared to crumble into dust (along with paint!), and it also seems to dissolve in water. I couldn't get a big enough chunk to put in a glass of water, but putting a wet Q-tip against one of the spots made it dissolve fairly easily. We have great ventilation in this bathroom, although I'm sure it still gets nice and humid in there.

So, do you all think it is efflorescence, or could it be something else? Thanks for your help!

bathroom wall-2.JPG bathroom wall.JPG

Water damaged Plaster. ( Repair, Paint )

**Lon Henderson** · 05-22-2013, 06:33 AM

Suspicious that water has penetrated the wall. Since the area needs to be repaired anyway, I would remove some of the drywall and see what the condition of the framing is inside.

**Heather** · 05-22-2013, 07:03 AM

Thanks to you both. I think there must be some salt, since some of the spots are clearly on the surface rather than coming from underneath the paint. I'm not really sure how water would have gotten into this wall, at least not from the outside, unless via condensation over the years. Unfortunately, this is a rental, so I have no idea what's behind that wall and it seems unlikely our landlord would be willing to fix it any time soon.

**Jerry Peck** · 05-22-2013, 07:04 AM

Originally Posted by Lon Henderson

Suspicious that water has penetrated the wall. Since the area needs to be repaired anyway, I would remove some of the drywall and see what the condition of the framing is inside.

Water (moisture from the tub/shower/etc) in the air has penetrated into the surface of the plaster.

About all you can do is remove the damaged areas, apply bonding agent (if the area is large enough), re-plaster, let it cure, then prime and re-paint.

Sometimes, if the damage is just at the surface, brush off the efflorescence down to good plaster, brush on some bonding agent, let dry, prime and re-paint. If the damage is not too deep, the bonding agent 'glues' it back together and makes for a better repair than doing more work on it does.

**Harry Janssen** · 05-22-2013, 03:59 PM

This is water damage,repair the cause,then fix the plaster and paint,other wise no matter what you do,the issue will come back.

**Jerry Peck** · 05-22-2013, 05:41 PM

Originally Posted by Harry Janssen

This is water damage,repair the cause,then fix the plaster and paint,other wise no matter what you do,the issue will come back.

"This is water damage"

Correct, it *is* "water damage", but what caused it and where the water came from need to be known before any repair of the cause.

Some here are assuming that "is water damage" from a leak or water intrusion, whereas it may in fact simply be from moisture in the air, it is, after all, in a bathroom and probably near a tub/shower from the tile shown in the one photo.

Before I would go about doing any major undertaking of 'trying to find a leak', I would first do some minor investigating to determine if the moisture may simply be air-borne (such as from a tub/shower). High humidity/moisture levels can cause plaster to have efflorescence just like that shown.

**Billy Stephens** · 05-22-2013, 06:00 PM

Looking at the pictures again looks like drywall not plaster.

Drywall with metal edge strips.

Metal edge strips just below the wall surface would cause condensation from warm moist air on the surface and damage the wall.

**Jerry Peck** · 05-22-2013, 06:54 PM

Originally Posted by Billy Stephens

Looking at the pictures again looks like drywall not plaster.

Drywall with metal edge strips.

Metal edge strips just below the wall surface would cause condensation from warm moist air on the surface and damage the wall.

Plaster on rock lath with metal corner bead ... or one coat plaster on plaster board with metal corner bead ...

The metal corner bead is not just used with drywall, metal corner bead is used for plaster too, the difference is the type of metal corner bead - typically rock lath and plaster has a metal corner bead with thicker expanded flanges for the brown coat and finish coat, the metal corner bead for plaster board and one coat plaster typically has thinner expanded flanges, sometimes the plasterer would use drywall type for one coat (work quite well for one coat). The metal corner beads are actually called "plaster grounds" as that is the level the plaster is screeded/finished to.

**Scott Patterson** · 05-23-2013, 06:14 AM

Originally Posted by Heather

Thanks to you both. I think there must be some salt, since some of the spots are clearly on the surface rather than coming from underneath the paint. I'm not really sure how water would have gotten into this wall, at least not from the outside, unless via condensation over the years. Unfortunately, this is a rental, so I have no idea what's behind that wall and it seems unlikely our landlord would be willing to fix it any time soon.

It's a rental! Tell the owner about it and when they do not do anything put a plant in front of it! Problem solved......