What they are
Fiber cement is a mix of cement, sand and cellulose fibers pressed into boards and panels. It is dense, heavy and rigid, does not burn, and is not eaten by insects. Connecticut’s code covers it in its own section (IRC R703.10).
Engineered wood is made from wood strands bonded with resins and treated against moisture and insects. It is lighter than fiber cement, easier to cut and handle, and comes in long lengths that mean fewer joints.
Both are sold primed or with a factory finish, and both look like the painted clapboard and shingle that Connecticut’s older houses were built with.
How they compare with vinyl
- Looks: deeper shadow lines and sharper detail; closer to real wood.
- Movement: both move far less with temperature than vinyl, so long walls stay flat.
- Impact: both resist dents better than standard vinyl.
- Maintenance: both need paint eventually and caulked joints kept sound; vinyl needs neither.
- Cost: both generally cost more than vinyl to buy and to install.
- Historic districts: commissions often look more kindly on a material that reads as painted wood. Check first. See our siding guides.
What installation gets right or wrong
Clearances
Both materials are kept a set distance off the ground and off any roof surface they meet, such as a porch roof or a dormer. The manufacturer specifies the gaps. They exist because a board that sits in snowmelt and splash-back wicks up water at its cut edge, and that is where siding fails. Siding run down into a mulch bed, or tight to a roof, is one of the most common installation faults we see.
Sealed and painted cut edges
Every cut end is a way in for water. Manufacturers call for cut edges to be sealed or primed, and joints to be handled to their instructions — flashed, gapped or caulked as the product requires.
Fastening
Fiber cement in particular is nailed to the manufacturer’s schedule, into the framing where required, with nails that do not crack the board or sink below its surface. Over-driven nails are a weak point that shows up years later.
Dust
Cutting fiber cement releases fine silica dust, which is a real health hazard, and federal workplace safety rules govern how it is cut. A proper crew cuts with dust-collecting tools or wet methods, away from open windows.
Behind any siding
Whatever goes on the outside, the code requires a water-resistive barrier over the sheathing (IRC R703.2) and flashing around windows and doors (R703.4). On a re-siding, any rotted sheathing found under the old siding is replaced first. See vinyl siding and siding repair or replacement.
Paint and finish
A factory finish is baked on in controlled conditions and generally lasts longer than a coat brushed on site. Primed boards are painted after installation, which means any colour you like, and a repaint down the road. Either way, the paint is part of what protects the board, so keeping it sound is part of owning it.
Older houses
On a house built before 1978, removing painted siding comes under the EPA’s lead renovation rule unless testing shows no lead. A full re-siding needs a building permit; repairs limited to 25 percent of the siding in a calendar year do not. Our siding guides cover the details town by town.
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Common questions about fiber cement and engineered wood siding
Is fiber cement better than vinyl siding?
It depends on what you want. Fiber cement looks more like painted wood, moves less with temperature and resists dents better, but it costs more, is heavier to install and needs paint maintained. Vinyl needs no painting.
What is the difference between fiber cement and engineered wood siding?
Fiber cement is cement, sand and fibers: heavy, rigid and non-combustible. Engineered wood is resin-bonded wood strands: lighter, easier to handle and available in long lengths. Both take paint.
Why does fiber cement siding need clearance from the ground?
A board sitting in snowmelt or splash-back wicks water up its cut edge, which is where siding fails. Manufacturers specify gaps from the ground and from roof surfaces.
Does fiber cement siding need to be painted?
It comes primed or factory-finished. Primed boards are painted after installation, and either finish needs to be kept sound over the years as part of protecting the board.
Is cutting fiber cement dangerous?
Cutting it releases fine silica dust, a health hazard covered by federal workplace rules. It should be cut with dust-collecting tools or wet methods.
Do historic districts allow fiber cement siding?
It depends on the commission. Many look more kindly on a material that reads as painted wood, but check with your town's historic district commission before choosing.