A major theme with our selection of materials and finishes was picking things that would be low or no maintenance, we felt this was especially important given waterfront exposure of the home. Early on we latched on to the idea of using a fiber-cement cladding called Cembonit (now called Cembrit Patina Original, Cembrit is a Danish company, no big surprise there, if you like modern things a lot of them come from Europe), which is through colored, pretty much maintenance free, has a nice modern look, and has some character, the surface has some grain and will weather a bit. The cost also seemed reasonable, at something a little over $7psf for the panels, though what I did not appreciate at the time was that fabrication and installation would be multiples of that. My better half was a little concerned about the house looking like a BMW dealership with this siding, but we looked at lots of photos and followed through on the initial idea. Initially we did look at a Spanish product called Prodema, a very nice phenolic that looks like wood, but we were warned it was expensive. Also some Meteon products, we were told those were expensive. For fiber cement I don’t think anyone in the US makes panels. JamesHardie makes fiber cement siding, but only for more conventional shingle and lapped applications. Silbonit (Italy) Equitone (Germany/Belgium), and SwissPearl all make nice fiber cement panels, I think Silbonit was similar cost to Cembrit and Equitone and SwissPearl were a bit more expensive (but again as I learned the material cost is not the major driver of this type of siding installation). We like the Cembonit Pearl color, kind of a creamy off-white (closest Benjamin Moore paint color to this was Soft Chamois, which we ended up using for most of the interior of the house, and also the exterior soffits). Eastern Architectural Products is the distributor for Cembrit in our area and they were helpful as we were looking at different options, another reason we went with Cembonit.
For the lower level our plan was to enclose the garage and storage area with Kynar coated corrugated aluminum (breakaway walls as we were in a flood zone), and we had the idea to bring this corrugated aluminum up over a corner of the main level to break things up. As we were getting the fascia up (Azek cypress color) and thinking about wood decking we came up with the idea of wrapping a corner of the house with Trespa Pura in their Romantic Walnut color. We floated this idea to Turkel and they thought it would work OK (some concern about having too many colors, but everyone got over that). At the time we got the Cembonit I think it came with a 25 year warranty, while the Trespa Pura was 10 years (including color stability).
For the rain-screen we had to choose something to use for furring. Because we initially thought about bringing corrugated aluminum up around a portion of the main level the architect specced 1.5″ furring strips (and brought windows out accordingly), but that seemed like a crazy large gap to me. We could have used aluminum or steel profiles and riveted the siding to those, but it did not seem like any of the subs had ever done that before and degree of difficulty may have been high. For that matter none of the subs had ever done fiber cement panels with reveals before either, we had lots of subs doing things for the first time with this house. Anyway, we figured we should keep it as simple as possible and go with wood furring strips and stainless screw fastenings (heads pre-painted to match the panels). We were planning to use Boral for some trim and thought about that for furring (it would never rot), but the distributor told us it was not suitable for “structural” applications like this. Our construction manager talked us into using primed mahogany furring strips, which cost a small fortune but are probably not going to be prone to rot. We used 5/4x4s most places, and 5/4x6s where panels met. So a 1″ air gap for the rain screen. The contractor who put the furring strips up, with long stainless screws, managed to miss the wall stubs in many places (in their defense maybe the wrap made it more difficult to see where the studs were), requiring some rework and leaving us with a bunch of holes in the wrap.
The final plan elevations included a guess at a siding panel layout, but that layout needed to be updated based on actual panel dimensions to balance efficiency and aesthetics (for latter having reveals line up with windows, etc.). I did the layout by hand using the plan elevations printed out on Arch D (242×36) paper. Initially I used the full panel size where possible, but Eastern Architectural Products suggested using all 1250x2500mm panels (49.2×98.4 inches), but a max size of 48.5×98, which as the tolerance for the full size panels is 1/8″ (3mm), and during fabrication they could trim everything down so things would be spot on. My layout was then the guide for placing the furring strips, which were placed such that fixing would be no more than 24″ horizontally (fastening spec is 16-24″ horizontally and vertically, and at least 1″ from the edge horizontally, and 2.75″ from the edge vertically).
Given that the idea of a rain-screen is that air can circulate behind the cladding I thought completely blocking off horizontal air flow was a bad idea, so I routed 1/4″ grooves every 6″ in all of the furring strips, groove side of the strips to be attached to the studs behind the sheathing. The black RevealShield SA wrap hid sheathing fasteners and the subcontractor putting the furring strips up missed the studs in a number of places, poking extra holes in the WRB and requiring rework (as with most of the quality control issues that arose during this project my construction manager did not catch this early on or at all, if I hadn’t caught it we probably would have ended up with some of the siding supported by OSB instead of framing). If I had a redo I might have had the crew applying the WRB mark the stud locations on the outside of the WRB.
The cost of having Eastern Architectural Products pre-cut and pre-drill the panels was nominal, and seemed like a much better option than having the sub that was going to install the panels cut and drill on site, which would have taken forever, cutting fiber cement panels is slow, creates a huge amount of dust, and dulls carbide/diamond blades and bits quickly. But to have the panels pre-cut and pre-drill required accurate field measurements, which I made. I spent a lot of time in a scissor lift measuring and remeasuring, and the final cut sheet was quite something. The lead time on the fabrication was 2+ weeks. We ordered a few extra panels (at $225 per) to allow for some breakage and unforeseen situations where we would need to fabricate on site.
A few takeaways on the installation of the panels:
1. We had a lot of breakage and ended up having to get a few more panels shipped to us (there were a couple of panels that were pre-drilled incorrectly, the supplier took care of us on this and we were able to just add some panels to the order). The 120-odd panels all had numbered stickers on them making identification straight forward, but at least initially panels were offloaded from the truck without recording which panels were in which pile, so there was lots of moving panels around to find the one that was going up next. It was also hard keeping contractors from stepping on the stacks of panels, several were broken because people stepped on them. Finally as they were moving and organizing panels they were often propped against lower level framing, crew left at the end of the day, wind came up in the night, and panels blew over, resulting in breakage. I was constantly laying panels down at the end of the day to try to keep this from happening.
2. Putting this stuff up was a very slow and exacting process, and there were several unanticipated snags. I mentioned incorrectly pre-drilled panels, that was one snag. Another snag was a modern home construction thing where sloppy construction quickly snowballs into increased cost. For example, one day I got a call while I was at the office as the siding crew discovered windows on each side of a corner of the house were not aligned, the bottom sills were offset by about an inch. With normal siding no problem. But here we have panels with reveals, and reveals lined up with window edges. So choice here was to have reveal not be lined up with the edge of some windows, or have reveals not line up at the corner of the house. We chose the latter, which I believe to be less noticeable. I think I might have taken the upper panel height from the higher window and carried that height around the corner, so in addition to the reveal miss at the corner we have to cut new (taller) panels to go next to the lower windows. As this material was going up we also discovered that the exterior walls of the home (interior ones too …) were not very straight. The Cembonit panels can flex some, but in some places it would have looked goofy if we did not shim to create a flatter plane for the mounting of the panels.
3. Adding to the time and cost of the siding was the installation of bug/animal screening. I don’t remember who suggested it, but we used Coravent S400 at the bottom of the lowermost panels. I thought we were also going to use it behind the horizontal reveals, but we didn’t and those (8mm) reveals are open. 2+ years in and I don’t think anything is living behind the siding. Also, another step required before siding went up was the installation of EPDM strips, these are available in 100mm width for wider furring strips where there will be a joint, and in 50mm (I think we just ordered all 100mm and cut in half for the 50mm), and must be fastened to furring strips before panels are screwed on.
The Trespa Pura was quite a bit more expensive than the Cembonit, almost $12psf, but was quite a bit easier to put up, so after labor I am not sure that it is not cheaper siding. Planks are 7″ wide by 10′ long and are easy to handle and cut. Color matched screws are available, as well as aluminum edge and corner trims. You screw the bottom plank on, then the planks above are notched and sit on top of the plank below, with hidden fasteners as you work your way up the wall. I put some of this up by myself, it was that easy.
