[skyisland]

I'm mainly an interior GC. One of my best clients owns a 5 story apartment building in NYC. On one side of the building there is a party wall through which moisture is infiltrating. As far as he knows, the history of the wall is that 25 years ago, the entire wall was given a trowel coat. After perhaps ten years the moisture problem returned and he was (poorly) advised to have it painted with Thoroseal and he hired a contractor to do that about eight years ago.

The Thoroseal is now coming off in many places, but it's still probably 80% covered.

On his behalf, I have brought in a few waterproofing specialists and have basically been given two solutions. Before I mention the solutions I should say that I have been told that party wall bricks which were never expected to be exposed to the elements are an inferior grade of brick. Whether this is true or not, I don't know although it would certainly make sense. The building that was next to it was torn down decades ago.

One guy suggests attaching steel mesh to the surface and applying a coat of stucco.

The second guy told me there are two problems with this solution. Firstly, the nail gun that will likely be used damages the bricks as well as the mortar and he says inevitably the stucco will begin to pull away from the wall over time. He recommends taking off the existing Thoroseal and stucco down to the brick and then troweling on a slurry coat and repointing as needed.

As it seems to me that his solution was basically tried (with the initial trowel coat of stucco) I'm unconvinced that this will solve it. I want to get the right solution for this client that will last for many years. I figured I should come straight to the pros and get your opinions. Many thanks.

 

[dom-mas]

It is very possible that what is now exterior brick was never meant to be exterior so was built with backup (soft) brick. Stucco sounds like the best solution to me. If the original coat only lasted 15 years or so before beginning to fail it sounds like it was improperly done. I've seen many stucco renderings that are decades old and beside a few cracks that need to be repaired are in decent shape and keeping the elements away from the brick. How many coats were put on to begin with, I don't do stucco but there are generally at least 2 coats and often 3 or more

Unfortunately I'm not familiar with thoroseal at all except from various references on this site, but thaey have all been positive in nature. I do agree that nailing lath to the brick is not a good idea, for both the reasons described.

has the parapet been checked for moisture infiltration?

 

[fjn]

I do agree with dom-mas that nailing lath would be a wrong move. With that said using tapcon screws would be the way to go.


Here is my recommendations,apply one inch of extruded polystyrene insulation to wall (proper foam glue and a few screws and fender washers to hold in place) .Attach with tapcon screws 3.4 lb. galvanized selt furring wire mesh,6" lap at seams and one screw per sq.ft. of wall area. Use Parex fiber reinforced stucco mix. Apply their elastomeric to coating. Call it done.


Make sure you go with the conventional stucco by them NOT their EIFS systems.

 

[skyisland]

Parapet wall and roof are in excellent condition. Just to be clear, this isn't a classic "leak" where water is seen in one or two spots. Basically in every apartment wall on the inside of that exterior party wall, the plaster or sheetrock crumbles and stains in several spots so it appears as if the entire wall from floor one to floor five just doesn't effectively keep moisture out.

 

[skyisland]

I do agree with dom-mas that nailing lath would be a wrong move. With that said using tapcon screws would be the way to go.


Here is my recommendations,apply one inch of extruded polystyrene insulation to wall (proper foam glue and a few screws and fender washers to hold in place) .Attach with tapcon screws 3.4 lb. galvanized selt furring wire mesh,6" lap at seams and one screw per sq.ft. of wall area. Use Parex fiber reinforced stucco mix. Apply their elastomeric to coating. Call it done.


Make sure you go with the conventional stucco by them NOT their EIFS systems.

That sounds nice and specific and will present your suggestion to both contractors and see how they react. I take it you're not worried about the tapcons doing too much damage to the brick?

 

[fjn]

No I'M not,they are less intrusive than powder actuated pins. Also,you can beef up the holding power by increasing the dia.of screws along with increased length of penetration into the brick.

 

[dom-mas]

Fjn's solution sounds pretty good to me

 

[JBM]

If its an old building the wall was probably built with lime and should be approached as such.

If it's not then carry on

 

[superseal]

Tapcons are going to run you a zillion$ and all that drilling just to put lath up

I normally just use stubs...3/8" to 2 1/2" and I'll hand pound them into the mortar joints. Very seldom will you see me fire masonry nails in the brick itself :no:

Could easily fancy it up a bit too and through some washers in the mix.

Another thing to consider on a job like this would be a Grade D WRB (double layer) paper, some rain screen and just pretend you're going over framing...A good quality fiber scratch and brown base coat, followed by the finish coat, texture coat or acrylic type finishes.

With a wall this size, you're going to need a lot of stop bead, weeps screeds and partition M-bead and cut this thing up like a checker board if you plan on fending off future cracking.

Here's the doweling magnet I use to set my stubs...certainly beats graded cheese fingers when not using pneumatics.

 

[Fouthgeneration]

I'd check and see if the owner of the other half of the "Party Wall" was A, still around, and B, and if solvent sue for repairs.

Where are the all the experts that inspected the building prior to his purchase? Errors and Omission insurance maybe?

These party walls aren't rocket science, You tear down your building, you must now weatherproof the remaining now exposed wall.... It is settled common Law. A few hours at the court house/city hall should indentify the offender(s).

Drying out the exterior wall will raise its R value, Installing a layer of insulation would save thousands a year in HVAC costs...Maybe some program funds/grants loans are availiable, but probablely attached to regulatory maze and platoons of flappers.

Whisper "black Mold law suits" and that should motivate your lax friend to take action or sell the soon to be condemed building.

The sooner repairs are started, the less masonry will need to be replaced and or Tuck pointed, If the party wall is going to remain exposed for the forseeable future, why not upgrade the wall with windows to raise the value of the property while the scaffold is in place to resurface the wall?

 

[fjn]

Tapcons are going to run you a zillion$ and all that drilling just to put lath up

I normally just use stubs...3/8" to 2 1/2" and I'll hand pound them into the mortar joints. Very seldom will you see me fire masonry nails in the brick itself :no:

Could easily fancy it up a bit too and through some washers in the mix.

Another thing to consider on a job like this would be a Grade D WRB (double layer) paper, some rain screen and just pretend you're going over framing...A good quality fiber scratch and brown base coat, followed by the finish coat, texture coat or acrylic type finishes.

I do agree,beyond a doubt,tapcons will be much more expensive however,I think with the history of this problem along with five stories of stucco the belt and suspender approach is warranted.


The foam will provide the rain screen(though Parex does offer such accouterments) The tapcons have the ability to be placed into the brick. I would be very gun shy to rely on fastners to be affixed to mortar. As far as tapcon purchases,in the past I have purchased in bulk straight from producers at a mere fraction of "wholesale" pricing. A good drill would dance holes in that old brick.