Plaster Wall Ice Damming Water Damage

Question

A couple weeks ago ice damming in my gutters caused a lot of damage to my plaster wall inside my house.

I got an estimate of around $2500 to fix the issue so I'm going to attempt it myself. Here is what I plan to do:

1. Remove the plaster from the wall in a rectangle from the right side of the window frame to the first stud past the right side of the water damage. Remove any of the damaged plaster outside of that area. The plaster is attached to wood lath.

2. Install moisture / mold resistant drywall over the wood lath in the large rectangular area where I removed the plaster.

3. Layer on plaster over the drywall and patch the other areas until the wall is smooth.

4. Paint.

My questions are:

1. Is there a specific type of drywall I should purchase for this job?

2. Is there a specific type of plaster I should use for this job?

3. Do I risk damaging the plaster molding just below the ceiling?

Any comments or things to consider when doing this job would be greatly appreciated. Thanks in advance!

UPDATE (3/17/2015):

Before I started to prep the plaster I cut a hole to double check there was never any insulation (there's none throughout the house) behind the wall and discovered that this situation had clearly occurred before (I just moved into the house four months ago) since there was already sheet rock screwed to the wall and plastered over.

I removed the sheet rock, as it seemed pretty messed up from the water damage. There was no insulation and everything seems pretty dry now. Here is what it now looks like:

UPDATE (4/05/2015):

Just wanted to give a quick update to show the finished result. This was my first real home improvement project and though it was daunting, and at times it seemed like I bit off more than I could chew, it came out great. Thanks for the help guys!

Answer 1

Before you attempt to repair it, make sure that the cause of the ice dam has been fixed. You may need to insulate the ceiling, and/or add a styrofoam vent baffle to the inside of the roof to prevent that area from getting too warm. Ice and water shield installed on the roof probably would have also prevented this from happening.

The repair will depend on how long the wall was wet and the extent of the damage. From what I am seeing, you should be able to fix this damage without needing to pull the whole wall apart.

Let the wall completely dry out and then check for signs of mold growth. A dehumidifier is not going to dry out the wall for you. You will also need fans aimed at the wall to circulate the air. Industrial blowers will do the best job, but a household box fan on high will also do.

Mold may be on the surface of the plaster, and it could also be under your trim. Use white vinegar to clean off the areas affected by mold and then use a mold killing primer such as Killz on all of the damaged areas.

Once the wall has been primed, then you can repair the plaster. You will need to get a bag of plaster of paris and a 5 gallon bucket of drywall joint compound. Mix the plaster with water per the instructions and mix in joint compound in a 50/50 ratio. Trowel on the mixture and blend the repair into the existing wall. The advantage of mixing the two is that you can use thicker coats of plaster without having it crack. It will also dry much faster and shrink less. The joint compound will make the repaired area harder and will bond better with the wall. Over time plaster dries out and becomes brittle. The gypsum in the joint compound will help prevent the plaster from deteriorating. In the old days, they would mix in chopped up animal hair (usually horse hair) to strengthen it instead.

You may need to apply more than one coat. You should also sand lightly between coats and feather the repair into the wall as best as you can. Any imperfections will be easily seen once the wall has been painted.

Once you are satisfied with the repair, then you can prime the wall. You can use any kind of primer that is compatible with the color coat. I prefer using primer that is rated for interior and exterior use since it is less likely to peel when you put the final coat on.

Repaint the wall and trim. If you can, repaint the entire wall at once so there isn't any differences in the sheen. It may look different if you only paint the damaged part.

Once the wall is painted, you shouldn't be able to tell that there was ever any damage there.