When we cut or drill into concrete or rock, crystalline sillica dust goes into the air. Inhaling that dust is dangerous, which is why OSHA established a new rule to protect workers from exposure to silica dust. Many manufacturers of concrete cutting tools have been engineering their products to address silica dust concerns for some time now. But there are few options available for cutting fiber-cement that control or eliminate dust.

Last winter we had a siding job come up and the customer wanted to use James Hardie fiber cement lap siding and shingles. The very first article I wrote for The Journal of Light Construction was on installing fiber cement lap siding. A few years later we reviewed using different methods for collecting dust when cutting fiber cement siding. Back in 2009 we reviewed the Ridgid R3400 dust collecting saw, which I liked very much. Other dustless, or low-dust options are available for cutting fiber cement – and all show some room for improvement.  Our local lumberyard started carrying the Roandust collecting saw, so I asked Tools to send one to us to try out.

No Vaccum? What caught my eye was the company’s assertion that the saw is designed to capture 90% of the dust particles without using a vacuum. This is a huge advantage when cutting fiber cement, especially when working off scaffolding. Dealing with cords is cumbersome enough, but adding a hose to the scenario makes it even more-so. 

The saw is designed so that the large plastic chamber behind the blade guard catches the larger particles of dust. You can see this dust swirl in the chamber as you cut. There is a second chamber behind the motor that houses a filter, which catches the smaller dust particles; Roan says that the “patented cyclonic action filters particles down to 2 microns”. The filter is intended to last the life of the saw if properly cleaned and maintained.

The filter exhaust is designed to accept a hose to increase dust collection. A HEPA vacuum is not required because the saw is equipped with a HMWP filter.

The manufacturer’s literature states that the main collection chamber should be emptied every “50 to 60 cuts” and recommends not overfilling the chamber with dust, because this will reduce the collection efficiency. We found this to be true.

The operating instructions also recommend “to clean the dust from the cyclone and filter chambers after every 100 linear feet of cutting or every hour, whichever comes first.” This takes just a minute because chamber has a rubber cap that is very easy to remove and reattach.

Features. This saw uses a standard 7 1/4” blade, and we found using a Diablo blade designed for fiber cement cut very smoothly; having a sharp blade seemed to cut down on dust. We like this blade much better than the Irwin blade we find at the lumberyard.

There is a depth adjustment that sits between the handle and the upper guard housing, which is convenient. Roan has made this handle longer so it's easy to adjust and the saw will bevel to 45°.

The Roan saw did a good job collecting dust when cutting single pieces of fiber cement material, but it did not do well when cutting multiple pieces at one time. The company acknowledges such in its operating instructions by saying to avoid stack cutting.
Tim Uhler The Roan saw did a good job collecting dust when cutting single pieces of fiber cement material, but it did not do well when cutting multiple pieces at one time. The company acknowledges such in its operating instructions by saying to avoid stack cutting.

Does It Work? The short answer is yes, it does work. We found that when we cut 1 piece of fiber cement, the saw collected dust very well, especially with a new, sharp blade. However, in the operating instructions on page 21 “Optimizing Dust Collection”, it says to avoid “stack cutting”, also known as “gang cutting”. For us in the trades, gang cutting is a common and necessary practice for both consistency and efficiency. As predicted, when we cut more than one piece at a time, and especially when we gang cut several pieces, a lot of dust got into the air.

Also, we found this saw is very cumbersome to use, especially when compared to shears or the Ridgid R3400, which is now discontinued. I asked the lumberyard after we used the Roan saw for a while what kind of comments they had gotten about it. They said that more than half tried to bring it back, but those that kept it said they like it.

After going through a unit of fiber cement, we decided to stop using this saw and switched to the Ridgid saw for the remainder of the house. Cutting fiber cement and capturing dust is not an easy task. It is cumbersome whether a vacuum is used or not. Eliminating dust totally using shears is a slow process, and pricey if you use a heavy-duty guillotine-style shear. I know many guys who just hold their breath when cutting fiber cement; that doesn’t help anyone who is working in the area.  There are no easy answers or perfect solutions to capturing fiber cement dust during a cut, which is why it’s hard to compete with siding contractors who don’t care about their health and will use zero dust collection.

The Roan saw retails for $180, and as of right now does not appear to be available online.


Tim Uhler is lead framer for Pioneer Builders,in Port Orchard, Wash. and a contributing editor to Tools of the Trade.