Lath and Stucco

The style of the home is something my wife and I are calling “Modern Tuscan“.  To us, this means a stucco and stone exterior.  While the majority of the Quonset hut will be buried, the Fox Block ICF endwalls would be visible (and prominent) and need to be stuccoed. But first, we would need to attach lath to hold the stucco.  Since the work was pretty standard, I decided to hire a professional to take care of the actual stucco work.  This is the story of how that all came together, but first, the video.

The Video

Lath overlap

As always, this is a journal of my progress, not a “how to”.  I don’t always do things the right way at the start, although I do usually learn from my initial mistakes.  For the lath, I read about attachment details like how often to put screws in each direction (and then I exceeded it), but I didn’t pay too much attention to the part about overlapping the lath and just butt jointed everything so the surface would be flatter for the stucco. Probably I was also thinking about saving on lath.  At a later point, I changed my mind, so the later pieces are properly overlapped…  Either way, the professional stucco guys said we did a good job and only needed to add some J-pieces to form the bottom edge.

The window

With such a large and prominent wall, I knew I needed a window to break up the space.  Personally, I think a square window would have looked stupid, so I bit the bullet and budgeted for a nice round window.  At least I went with a standard diameter window so it wouldn’t need to be custom.

However, when I finally got to this stucco stage, I wasn’t ready to order the windows. I want to order them all at once to get the bulk discount, and I wanted to build all (or most) of the bucks before I order, so…  In the meantime, I decided to go with polycarbonate Lexan.  This is pretty basic stuff that you can buy from Home Depot less than 1/10th the price of a window.  The R-value is also pretty similar to a double pane window.  I figured it would at least give us a temporary solution that would keep the inside dry over the winter.

It ended up looking so good, I might just decide to keep it this way.  We will see how well it holds up to UV.  Obviously, if it yellows or cracks over time, I will switch to glass.  But it did claim to be “UV stable” and has looked fine so far, so I am optimistic.

Still, I wanted to make sure that the window opening was ready for proper glass so that the stucco edge would all be done correctly.  We used wood strips to form a curb, and then put two layers of the tar paper to protect the wood and then a strip of lath to hold the stucco.  Lots of screws…

Getting a Contractor

I have had many struggles with getting contractors to work on the more unusual parts of my build, but I was surprised to even have trouble getting something as basic as “stucco over ICF”.   Very few of these companies advertise properly, probably because most are kept busy by professional builders and are not actually looking for work. Eventually, I went to the stucco supplier and asked for a list of names and recommendations.  One of those paid off, but even then I had to wait quite a while to fit into the schedule.

Of course, the contractor, Hoffman Plastering, did a great job in terms of how nice and flat the wall was (they certainly had to compensate for my less than professional ICF job).  Their classic worm finish was also excellent.

Cracking

However, in the months after the stucco was applied, we did get a bunch of fairly obvious cracks in various places and we have not been able to get them to come out and take a look.  On the phone, they said that it was probably my fault. Essentially, they blamed the copper cap and said that water probably got behind the stucco and froze, but I was able to find pics showing the start of the cracks before the first freeze, also the cracks look more like ones that are caused by expansion and contraction of the stucco its self.  Basically, I imagine that if the south wall expanded in the sunshine, this narrow region would be the highest stress concentration and the most likely to crack. The inspector thought it may have been that the top layer was applied too soon after the brown coat. The contractor may have rushed that step because the work was done in October. The cracks are not wide enough to get the edge of a coin or screwdriver in there, but are still concerning. The conclusion of this story is still on hold, but I should probably do something before winter when water might actually get in thru those cracks and cause further problems when it freezes.

Future Stucco?

I wish I could hire a contractor to stucco the rest of it.  Their work was excellent (other than the cracking) and the quote to handle the rest of it was probably fair per square ft.  The problem is just the large number of square ft required. The majority of the cost is the professional labor, the actual materials are a very small fraction of the cost.  Therefore, I am guessing I will need to do it myself. With any luck, my skills will grow quickly.

Gallery

As per usual… A collection of pics related to the lath and stucco.

Lath is ready on the north side…

Working with Hunter Mitchell often made me smile.

A view thru the Polycarbonate Lexan window

The window ready for stucco

I put a septic hookup on the front of the house for friends with campers.

This was the stucco setup. Scaffolding ready in the back and a stucco mixing station in the front left.

I took pics of the ingredients. Basically, it was just cement, hydrated lime and masonry sand. I’ll probably have to do this myself next time.

The bags of hydrated lime looked pretty old ;^)

The stucco sample. I would say it looks pretty much exactly like the final work.

Scratch coat near the ends of the walls.

Scratch coat with the light base.

Scratch coat near the north garage door.

Scratch coat on the north side

Since I couldn’t come out (busy working to pay for the stucco), Sherri and Boys would go out to check on things and set up my camera.

Sherri and David posing while they set up the camera.

The wide angle GoPro always makes things look different.

Brown coat, first 7 ft.

Hoffman plastering did a great job with the stones.

Stone arch is in. Note the stones are not really wedge shaped, but it still looks good.

Stone arch is in

Scratch done.

A little progress pic of the brown coat, scratch coat and final stone work all in one shot.

Brown coat finished on the front.

This is a section on the north side by the garage door that was still only scratch coat 3 days before they were totally done. I suspect they rushed these last steps and the result will be that the final stucco will crack along with the base coat instead of being applied after it cracks.

This ugly spot will be covered over by window trim, but I wanted to show you how the guys from Hoffman plastering went the extra mile. The back wall had some issues with being plumb and straight near the rear windows. I thought it was just the way it was going to be, but they just went really thick (~2 inches) until they got it all nice and plumb again.

Suddenly, final stucco

Final stucco coat

The final job looked really excellent.

Stones above the door.

A close up of the top of the column between the stones. The white patch is just the electrical box for the lighting.

Final stucco near the round window. They did a great job on that edge.

A close up of the final stucco

A little while later after adding the lights and copper trim… (notice cracks are already starting to form to the left of the light)

The skid steer just barely fits under the stone arch… I hold my breath every time I go in or out.

Cracks started to firm. Here is a pic with my hand for scale. This is on the north side.

On the south side, the main cracks were across this narrow space between the corners of the doors and the outer edge. I can imagine that this is due to expansion finding the weakest part to crack…

Similar geometry on the South West corner leading to a similar crack.