What Siding Holds Up Best in Maryland Weather

Fiber cement handles Maryland's freeze-thaw cycling best, with engineered wood close behind, though well-installed vinyl performs better than its reputation. The material matters less than the water-resistive barrier, window flashing and kickouts behind it. Remodel Now installs siding across the Baltimore-Washington Metro Area, and that hidden assembly is what to confirm any bid includes.

What the weather here actually does to a wall

Start with the numbers, because they explain most of what goes wrong on Maryland siding.

At BWI, the 1991 to 2020 normals put about 93 days a year with a low at or below 32 degrees, but only about 11 days where the temperature never climbs back above freezing. Subtract one from the other and you get roughly 80 days a year when the thermometer crosses the freezing line and crosses back. That is the freeze-thaw count that matters. Any water sitting in a porous material on your north wall gets a chance to expand about eighty times a winter.

The same station records 45 inches of precipitation in a normal year, spread over 121 days with measurable rain and about 11 days that drop an inch or more. Add 29 thunderstorm days, most of them in summer, and you have a lot of rain arriving sideways with wind behind it.

Then summer. The normal July mean dew point at BWI is 68 degrees, and the normal 7 a.m. relative humidity runs 80 percent in July and 84 percent in August. Thirty-four days a year hit 90 or higher. A wall that got wet in the spring is trying to dry into air that is already loaded.

Maryland sits in the mixed-humid climate zone, zone 4A, everywhere except Garrett and Allegany counties out west, both of which the 2021 code tables put in zone 5A. Mixed-humid is the hard case. The wall has to dry outward in winter when you are heating, and inward in summer when you are cooling, and the direction flips a couple of times a year. A wall assembly that only dries one way will eventually trap something.

Water gets behind the siding. What happens next is the real question

Most homeowners have never been told this part. Siding is not a waterproof layer. It is a screen. On any lapped cladding, wind pushes water up and under the laps, capillary action pulls it along the back face, and nail holes give it a path. Building scientists have described rain control as deflection, drainage and drying for decades, and all three have to work.

So the siding sheds the bulk of it. The layer behind the siding, the water-resistive barrier, is what actually keeps water out of your sheathing and framing. Flashing is what moves water from behind the siding back out to the face, especially at every hole somebody cut in the wall.

Code says this plainly. Section R703.1.1 of the International Residential Code requires the exterior wall envelope to prevent water accumulating in the assembly, using a water-resistive barrier behind the veneer plus a means of draining water that gets in. R703.2 requires at least one layer of that barrier, lapped shingle-fashion. R703.4 lists where corrosion-resistant flashing is mandatory: window and door openings, chimney intersections, under and at the ends of copings and sills, continuously above projecting wood trim, where porches and decks and stairs attach, at wall and roof intersections, and at built-in gutters.

Baltimore County spells it out on its own permit page. When you replace siding, a water-resistive barrier goes on first, and flashing goes around all windows and doors and has to extend to the face of the finish or to the barrier so the water drains. That language exists because crews skip it.

Pick whichever material you like. If the barrier is torn, the window has no sill pan, and the roof-wall intersection has no kickout, the material will not save you.

Fiber cement in a freeze-thaw climate

Fiber cement is cement, sand and cellulose fiber pressed into board. It does not rot, insects ignore it, and it holds paint better than almost anything else because the surface is stable.

Its weakness is the one our winters test. The board is slightly porous. Soak it, freeze it, thaw it, repeat eighty times, and a poorly made or poorly installed board can delaminate at the edges. Manufacturers responded by building region-specific formulations. James Hardie splits its products into HZ5 for northern freeze-thaw climates and HZ10 for hot humid and coastal ones, and Maryland is HZ5 territory. If a bid does not say which, ask.

Installation is where fiber cement earns or loses its reputation. The published clearances are not suggestions. Six inches from finished grade. Two inches from a roof surface, a deck, a walk, a patio or a step. A quarter inch above horizontal flashing, left open, not caulked, because that gap is the drainage path. Field butt joints get flashing behind them. Blind nailing is the preferred method, with face nailing only where high-wind requirements call for it.

Fiber cement comes off plenty of houses with every one of those violated. Boards buried in mulch wick water up the bottom edge. Boards tight to a shingle roof sit in the snow drift that forms there every February. Butt joints caulked instead of flashed trap water inside the joint instead of letting it out.

It is also heavy, the cutting dust is a respiratory hazard that requires real control measures, and the sheets fight you on a windy second-story wall. None of that is a reason to avoid it. It is a reason to care who installs it.

Vinyl, judged honestly

Vinyl gets dismissed more than it deserves and oversold more than it deserves. Both are true.

The honest case for it: vinyl does not rot, does not need paint, and by the nature of its profile it hangs off the wall with air behind it. Joseph Lstiburek's own point about back-ventilation is that typical vinyl and aluminum siding already have plenty of air gap behind them without doing anything extra. On a house with marginal sheathing drying, that accidental gap is a genuine advantage.

The honest case against: vinyl moves a lot with temperature. A twelve-foot panel grows and shrinks measurably between a January night and a July afternoon, and the entire system is designed around that. Nails go in the center of the slot, not at the end. You leave roughly a thirty-second of an inch between the nail head and the nailing hem so the panel can slide. You leave expansion room where panels enter trim, more of it when you are installing in cold weather.

Nail it tight and it will buckle in the first heat wave or tear off in the first serious wind. Most of the wavy, oil-canned vinyl you see driving through Parkville or Glen Burnie is not bad product. It is a crew that drove the nails home.

The other problem with vinyl is cultural. It is the material people choose when they want the house to stop needing attention, which means it is the material most often installed straight over whatever was there, with no barrier work and no flashing corrections. That is the version that fails, and the material gets blamed for it.

Engineered wood

Engineered wood siding is wood strands treated with resin and a zinc borate compound, pressed into boards that look like cedar and behave more like a manufactured product. LP SmartSide is the name most people know.

It splits the difference well. It is much lighter than fiber cement, which matters on a two-story gable where a heavy board is a two-man lift all day. It comes in long lengths, which means fewer butt joints, which means fewer places to fail. It takes a nail without pre-drilling, holds paint, and resists impact better than fiber cement, so a weed trimmer or a stray ball does not chip it.

Clearances are tighter than Hardie's in places and the same in others. Six inches to finish grade. One inch at the roof line. One inch above porches, patios and walks.

Its real vulnerability is cut edges. The factory seals the board. Your crew cuts it, and every cut exposes untreated strand. If those edges are not primed and sealed before the board goes up, water finds them, the strands swell, and you get the puffy, swollen bottom edge that gives engineered wood its bad reviews. Ask a bidder directly how they handle field cuts. The answer tells you a lot about the rest of their work.

Cedar, and the bargain it asks for

Nothing else looks like cedar. A clear vertical-grain bevel wall on a 1930s Roland Park house or a Frederick farmhouse is worth protecting, and no composite replicates it convincingly up close.

What cedar asks in return is maintenance and discipline at installation. Wood moves with moisture. The Western Red Cedar Lumber Association position, and most careful carpenters agree, is that siding should be finished on all six sides before it goes on the wall, back, face, edges and ends. Finishing one face and leaving the back raw creates an imbalance: the board absorbs from behind, dries from the front, and cups. Pre-finished, ideally factory-finished, boards stay flat.

Cedar also wants air behind it. The association's own guidance describes nailing to furring strips where an air space is desired, and in 45 inches of annual rain with August dew points in the sixties, it is desired.

Then there is the honest part. In this climate, a painted or stained cedar wall on a south or west exposure will want attention on a cycle, and that cycle is shorter than people hope. If nobody in the house is going to get on a ladder or hire it done, cedar is the wrong call, and the house will tell you so within a decade. Cedar makes the most sense on accent areas, on historic properties where review boards expect it, and for owners who actually like maintaining a house.

The four side by side, on terms that matter in Maryland

  • Fiber cement. Freeze-thaw behavior: Good in the correct regional formulation; porous, so clearances and drainage matter. Summer humidity: Dimensionally stable, does not swell. Wind-driven rain: Rigid, stays put; joints need flashing. Recoating: Holds paint a long time. Weak point: Buried edges, caulked joints, roof contact.
  • Vinyl. Freeze-thaw behavior: Unaffected; brittle in deep cold under impact. Summer humidity: Unaffected. Wind-driven rain: Can unzip in high wind if over-nailed or under-locked. Recoating: None. Weak point: Installed tight, hides problems underneath.
  • Engineered wood. Freeze-thaw behavior: Good; treated strand resists cycling. Summer humidity: Stable if edges are sealed. Wind-driven rain: Long panels, fewer joints. Recoating: Holds paint well. Weak point: Unsealed field cuts.
  • Western red cedar. Freeze-thaw behavior: Moves seasonally, needs room. Summer humidity: Absorbs and releases; cups if unbalanced. Wind-driven rain: Good behind a drained gap. Recoating: Shortest cycle of the four. Weak point: Back face left unfinished, no air space.

Set those four against each other and the pattern is hard to miss. Most of what separates them is installation, not what the board is made of.

The details that actually decide the outcome

When a wall fails in Maryland, it is almost never the siding that failed. It is one of these.

The barrier. Housewrap stapled up and never taped, with the laps running the wrong direction, drains water into the sheathing instead of down the face. The barrier has to lap the flashings by a couple of inches, upper over lower, the way shingles work.

Window and door openings. This is the number one leak on houses built in the subdivision boom. A sloped sill pan under the window, flexible flashing up the jambs, head flashing over the top, and the barrier lapped over the head flashing. Taping the nailing fin on four sides and calling it done is not the same thing, and it fails at the sill where it matters most.

The kickout. Where a roof eave dies into a sidewall, something has to throw the water out into the gutter instead of letting it run down the wall and behind the siding. The IRC requires corrosion-resistant flashing at wall and roof intersections, and it sets the size. Section R905.2.8.3 requires base flashing against a vertical sidewall to be not less than four inches high and four inches wide, and to direct water away from that wall onto the roof or into the gutter. James Hardie's own drawings cite that section back rather than inventing a number, so the four by four is a code minimum and not a manufacturer preference. A missing kickout is the single most reliable way to rot a stud bay from the outside, and you will not see it until the drywall inside stains.

Z-flashing and trim. Horizontal joints in panel siding, the tops of windows and doors, the top of a band board. Every horizontal interruption needs metal that sends water out over the course below.

Penetrations. Hose bibs, dryer vents, electrical, the lag bolts holding a deck ledger. Each one is a hole in your barrier. Each one needs flashing or a proper block and sealant, and the deck ledger connection specifically is called out in the code's flashing list.

Clearances. Grade, roof, deck, walk. The grade also has to slope away from the house. A perfect siding job on a yard that drains toward the foundation is a losing position.

When a rainscreen gap earns its keep

A rainscreen is nothing exotic. It is a deliberate air space between the back of the siding and the water barrier, usually created with vertical furring strips or a drainage mat, so water that gets behind the cladding drains out and air can move through and dry the assembly.

On gap size, Lstiburek's answer is three-eighths of an inch, and he is explicit that this is a conservative number for claddings that lie flat against the wrap, which includes wood, fiber cement and stucco. He also notes that vinyl and aluminum already have their own gap.

Why it matters more now than it did in 1960. Older houses were sheathed with board or plywood, both of which absorb a little water and redistribute it. Most houses built in the last thirty years are sheathed with OSB, which does not do that nearly as well. Fill the stud cavities with dense insulation and the sheathing has very little ability to dry inward either. The gap gives it a way out.

The code does not force your hand on lap siding. The 2021 code added a required drainage space behind stucco and adhered masonry veneer in wet regions, but it does not mandate a rainscreen behind fiber cement or wood lap siding. That makes it a judgment call, and the judgment usually runs like this.

Furr the wall when the house has no roof overhang to speak of, when the exposed elevation faces west or northwest into the weather, when the cavities have been spray-foamed, when the sheathing is OSB and the cladding will be fiber cement or wood, or when you are already finding old moisture damage. Skip it on a sheltered single-story with deep eaves and vinyl going back up.

Furring is not free of complications. It pushes the cladding out, so window and door trim has to be extended, corner details change, and the top and bottom of the cavity need to be detailed so it vents without becoming a highway for insects. A crew that has not done it before will fumble those.

A 1950s rancher and a 2005 colonial are two different jobs

This is the part estimators skip and homeowners find out later.

Pull the siding off a 1950s house in Woodlawn, Parkville or Dundalk and you may find one-by board sheathing laid diagonally, with asphalt-saturated felt, rosin paper, or nothing at all behind the original wood siding. Frequently there is aluminum or asbestos-cement shingle installed in the 1970s right over the original, which means two layers coming off and a disposal plan for the second one. The walls are rarely flat. Furring or shimming is often the only way to get a straight plane. The sheathing boards may have gaps wide enough to see daylight. Anything painted before 1978 brings the federal lead rules into play once you disturb more than about 20 square feet of exterior painted surface, which a re-side always does.

Pull the siding off a 2005 colonial in Bowie or Owings Mills and the problems are different and more specific. OSB sheathing, housewrap that was stapled and never taped, window flanges taped on the jambs and head but open at the sill with no pan, no kickout at the roof-wall intersections, and builder-grade vinyl over all of it. The wall looks fine until you reach the two or three spots where water had a path, and there you find black sheathing, soft studs and sometimes a rotted band joist.

Either way, the siding is the easy part. The sheathing repair, the framing repair, the barrier and the flashing are the job. Any bid that does not include an allowance for unknown rot discovered after demolition is either optimistic or incomplete, and you should ask how that gets handled before the first board comes off rather than after.

Permits, licenses and review boards, county by county

Permit authority in Maryland is local, not statewide, and the rules genuinely differ from one county in this region to the next.

In Baltimore County, residential siding does not require a permit unless the property sits in a proposed or designated county Historic District or appears on the county Landmarks List. Commercial siding always requires one. Baltimore County adopted the 2021 International Residential Code under Bill 49-24, effective September 2024, and the county's own permit page restates the barrier and flashing requirements regardless of whether a permit is pulled. No permit is not the same as no code.

Montgomery County lists siding among the work that most likely does not require a permit, alongside roof covering and like-for-like window replacement, with the caveat that exempt work still has to comply with the building code and with any municipal or HOA rules. Prince George's County runs its permitting through DPIE, and the right move is to check their current list rather than assume.

Baltimore City is the one that catches people. If the house is in a local historic district, the Commission for Historical and Architectural Preservation requires an Authorization to Proceed before a building permit is issued, and the commission reviews the proposed material against its design guidelines. That changes which products are on the table, and it is not a conversation you want to start after the material is on the truck.

On licensing: Maryland home improvement contractors are licensed by the Maryland Home Improvement Commission. The license number belongs on your contract, you can verify it yourself through the commission's public license search, and the commission's regulations put the obligation on the prime contractor to obtain or confirm every required permit. The Guaranty Fund that compensates homeowners for a contractor's failure only applies to work performed by a licensed contractor, which is the practical reason to check rather than assume.

Before you sign anything, ask the bidder: What goes on behind the siding, and is it being replaced or reused? Who flashes the windows, and what does the sill detail look like? Are there kickouts at every roof-wall intersection, and will you add them if they are missing? What clearance are you holding at grade and at the roof? How are field cuts sealed? What happens when you open a wall and find rot? Is your MHIC number on this contract?

Remodel Now installs fiber cement, vinyl, engineered wood and cedar siding on homes throughout Baltimore County and the wider Baltimore-Washington Metro Area, and the barrier and flashing work behind the cladding is the part worth getting written into the exterior scope rather than left as an assumption. We work in Baltimore, Towson, Parkville, Owings Mills and south through Silver Spring and Bowie. If the condition of the wall behind your siding is the open question, call (301) 798-4696 or get in touch.

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Frequently Asked Questions

Which siding material lasts longest in Maryland?

On material alone, fiber cement and engineered wood are the two that handle our freeze-thaw cycling and summer humidity with the fewest compromises, and both hold paint well. Good vinyl, correctly hung, also lasts a long time and never needs paint. The honest answer is that identical materials on two houses a block apart will age very differently depending on whether the water-resistive barrier, the window flashing and the kickouts were done right. Material choice sets the ceiling. Installation decides where you land under it.

Do I need a permit to replace siding in Baltimore County?

For a typical single-family house, no. Baltimore County requires a permit for residential siding only when the property is in a proposed or designated county Historic District or appears on the county Landmarks List. Commercial siding always requires one. That said, no permit does not mean no code. The county's own permit page states that when siding is replaced, a water-resistive barrier goes on first and flashing is required around all windows and doors. Rules differ in Baltimore City, Montgomery County and Prince George's County, so confirm for your specific jurisdiction.

Is fiber cement actually better than vinyl in a freeze-thaw climate?

It depends what you are measuring. Fiber cement is rigid, dimensionally stable and takes paint for a long time, which is why it reads as the premium choice. It is also slightly porous, so a board installed in contact with the roof or buried in mulch can suffer in freeze-thaw cycling. Vinyl is unaffected by freezing but becomes more brittle under impact in deep cold, and it will buckle or blow off if the installer nailed it tight. Both work here. Neither forgives a sloppy crew.

Does the housewrap have to be replaced when siding is replaced?

In practice, almost always, and the code points the same direction. The International Residential Code requires a water-resistive barrier behind the exterior veneer along with a means of draining water out of the assembly, and Baltimore County restates that requirement for siding replacement. Old barriers are usually torn, improperly lapped, or missing entirely on pre-1960 houses. Once the siding is off, replacing the barrier and correcting the flashing is the cheapest it will ever be to do. A bid that leaves the old wrap in place is leaving the actual waterproofing to chance.

What is kickout flashing and why does everyone talk about it?

It is a small bent piece of metal at the spot where a sloped roof eave dies into a vertical wall, usually just above a gutter end. Its job is to throw water out into the gutter instead of letting it run down the wall and behind the siding. The IRC requires flashing at wall and roof intersections, and Section R905.2.8.3 sets the minimum at four inches high by four inches wide, directing water away from the wall and onto the roof or into the gutter. That dimension is code, not a manufacturer preference. Leave it out and you will rot the wall behind it, often for years before anything shows inside.

Do I need a rainscreen behind my siding in Maryland?

It is not required behind lap siding, and plenty of walls perform fine without one. It earns its keep in specific situations: no roof overhang, a west or northwest exposure taking the weather, OSB sheathing with spray foam in the cavities, wood or fiber cement cladding that lies flat against the wrap, or a wall where you are already finding old moisture damage. The working number for the gap is about three-eighths of an inch. Vinyl and aluminum already have air behind them by design, so furring adds less there.

Can new siding go over the old siding?

Physically yes, and it happens constantly. It is also how a great many bad walls got that way. Siding over siding hides whatever is rotting underneath, prevents you from inspecting and correcting the water-resistive barrier, and makes it much harder to flash windows and roof intersections properly because everything is now built out past the original plane. On a 1950s house with aluminum over the original wood, you are usually looking at two layers coming off. Tear-off costs more and it is the only version where anyone can tell you what shape the wall is in.

How do I confirm a siding contractor is licensed in Maryland?

Maryland home improvement contractors are licensed by the Maryland Home Improvement Commission, part of the Maryland Department of Labor. The license number is supposed to appear on your contract, and you can verify it yourself through the commission's public license search before signing anything. The commission's regulations also put the obligation on the prime contractor to obtain or confirm any required permits. One more practical reason to check: the state Guaranty Fund that can compensate homeowners for a contractor's failure applies only to work performed by a licensed contractor.

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