Wind first: what a 90 mph gust asks of a wall
NOAA's engineering weather data for Augusta/Bush Field gives a 50-year basic wind speed of 90 mph, measured as a 3-second gust at 33 feet. That number is a design benchmark, not a forecast, but it tells you the kind of push and pull a wall in Augusta should be built to take.
Wind does not simply press on siding. As it wraps around corners and over eaves it creates suction on the downwind walls and along the edges of the house, and that suction tries to peel the bottom edge of each lap course away from the one below it. Siding usually lets go in a predictable order:
- Corners and gable ends first. The edges of a wall see the strongest suction, so loose pieces there tend to be the first to flap, crack or blow off.
- The lock between courses. Vinyl and some composite panels hold each course by hooking it into the one beneath. If a panel was not snapped fully into its lock, a gust can unzip a whole run.
- Trim that was only glued or caulked. Corner boards, window casings and frieze boards that rely on sealant instead of fasteners can pull away and let water in behind them.
- Short or sparse nails. A nail that only reaches into the sheathing, or nails spaced farther apart than the product allows, gives wind more leverage on every panel.
None of this means a house needs exotic materials. It means the installation has to follow the maker's instructions to the letter. Many siding products publish separate fastening schedules for higher wind ratings, with closer nail spacing, longer nails, or a specific nail head. Ask each bidder which schedule they plan to follow, what nails they will use and how deep those nails will reach into framing or sheathing. Ask whether they will use the maker's starter strip and how they will secure the top course under the soffit, where wind often gets its first grip.
For vinyl in particular, the nail should be centered in the slot and left slightly proud so the panel can slide as it heats and cools. A panel nailed tight cannot move, buckles, and then catches wind. For fiber cement and engineered wood, ask about blind nailing versus face nailing and which one the product's wind rating assumes.
Rain that comes in sideways
The same NOAA set lists a 100-year rainfall rate of 4.0 inches per hour for Augusta/Bush Field. When rain like that arrives on a stiff wind, it does not fall straight down; it is driven into laps, joints and the gaps around windows. Siding is a rain screen, not a waterproof skin, and the layer behind it does the real work.
Ask each contractor to describe:
- the water-resistive barrier they will install, how the seams lap shingle-fashion, and which seams are taped;
- the flashing at window and door heads, and kick-out flashing wherever a roof edge dies into a wall;
- how they will seal around hose bibs, dryer vents, meters, outlets and cable entries;
- how water that reaches the bottom of the wall gets back out.
Wet-bulb hours and how a wall dries
By NOAA's count, Augusta/Bush Field logs about 1,242 hours a year when the wet-bulb temperature is above 73°F, and about 2,890 hours when it is above 67°F. Wet-bulb temperature tracks moisture in the air as well as heat, so those hours describe how long the air around a wall stays loaded with water.
A wall that gets wet behind its siding needs moving air to dry, and damp air slows that down. Ways to give a wall a better chance:
- A drainage gap. A rainscreen mat, furring strips or a drainable housewrap leaves a small space so water can run down and air can move. Ask whether the bid includes one and what it adds.
- Ground clearance. Ask how high the lowest course will sit above soil, mulch, patios and walks.
- Vented soffits. If soffit panels are part of the job, ask how attic air will flow once they are on.
- Room around plants. Shrubs touching the siding keep the bottom of the wall wet; leave a gap.
Heat, cold and movement
NOAA's design figures for Augusta/Bush Field (elevation 148 feet) put the 1% summer design temperature at 94°F, with a mean coincident wet-bulb temperature of 76°F, and the 99% winter design temperature at 25°F. Siding expands and shrinks across that span. Vinyl moves the most and needs the expansion gaps its maker calls for at corner posts and J-channels; ask how the crew adjusts those gaps on a hot install day versus a cool one. Fiber cement and engineered wood move less but still need the joint spacing and sealed cut ends their instructions require. Paint and caulk carry temperature limits on the label, so ask how the schedule handles a very hot afternoon.
Picking a material
- Vinyl costs less up front and needs little upkeep. It depends entirely on correct, loose fastening, and a cheap thin panel flexes more in wind.
- Fiber cement is heavy, resists rot and insects and holds paint well; every cut end needs sealing and the nailing must match its wind instructions.
- Engineered wood is lighter and easy to work, and it relies on sealed edges and good clearance above the ground.
- Wood suits many older houses and needs paint or stain on a regular cycle and close watching for rot.
Ask each bidder what they would put on your house, why, and for the installation guide they will follow.
The company and the paperwork
Ask the contractor what state license, if any, the business holds, and look it up on the Georgia Secretary of State's license verification. Ask for proof of liability coverage and workers' compensation, and check that the business name on those papers matches the contract. Ask which permits the job needs, if any, and who pulls them.
Lining up bids
Give every bidder the same list to price in writing: tear-off and disposal, the product with its thickness or grade, the weather barrier and any drainage layer, flashing, trim, soffit and fascia, a per-sheet price for sheathing repair, the fastening schedule, permits, cleanup, the start and finish dates, and both the product and workmanship warranties. Read the bids line by line. When one total is far lower, look for what it left off, often flashing, the drainage gap or the wind fastening the product calls for.