Why Is One Siding Quote Double Another?

A quick word on who is talking. Run this search and the whole first page is people who get paid the day you hire a siding crew: the installer's own blog, the panel manufacturer, or a lead broker that resells your phone number to three crews at once. We nail up no siding and we broker no leads. That lets us say what they will not, which is that the pricier bid is sometimes the honest one, and the cheap one sometimes is not a bargain at all. It is the same wall, with the hard parts quietly left off the page.

The gap is a scope gap, not a greed gap

One crew plans to strip the old siding to the sheathing, hang a fresh weather barrier, re-flash every window and the spots where the roof meets a wall, and swap out rotted wood as they find it. The other plans to nail new panels over whatever is already on the house and call it done in half the days.

Same address, same wall footage, two different amounts of work. At that point you are not comparing prices. You are comparing a full re-clad against a cover-up, and the number at the bottom is just the receipt for whichever one you picked. What a square of siding should actually run is a different question, and our siding cost guide answers it. This page is about which of the two bids in front of you is pricing the whole job.

Tearing off vs. going over the old siding

This is the single biggest fork in a siding bid, and it usually goes unspoken. Pulling the old siding and carting it away is real labor and real dump fees, and on vinyl or aluminum it tends to add somewhere around $0.50 to $1.25 a square foot to a bid. Going right over the top skips all of it, which is exactly why the cheaper bid can look so good. Read that range as the distance between your two quotes, not as a price list.

Going over the old stuff traps whatever is under there against your wall, hides any rot instead of fixing it, and often needs furring strips to give the new panels a flat surface to sit on. A good installer will tell you which one they are doing and why. A cheap one just nails over the past and never mentions what got sealed inside the wall. If one of your quotes is a tear-off and the other is a cover-up, you have already found most of your price gap.

Walls only, or the whole house?

Here is a swing that catches people flat. Some siding bids price the flat wall panels and nothing else. The trim is a separate story: the soffit and fascia up under the eaves, the casing around every window and door, the freeze board, the trim on the garage. Wrap all of that and the same house can climb by thousands without either crew touching a single wall panel.

So before you compare a single dollar, ask each bidder one question: is this walls only, or does it cover the trim, soffit, and fascia too? A bid that is "walls only" is not cheaper than one that wraps the whole house. It is just smaller, and the rest shows up later as a change order or a second contractor.

The word "vinyl" on a bid tells you almost nothing

A line that just says "vinyl siding" is not a specification, because vinyl comes in a spread of thicknesses that do not cost the same and do not hold up the same. Here is the part nobody tells you. CertainTeed's own code evaluation report, the one filed with ICC-ES as ESR-1066, says its siding panels range in thickness from 0.036 inch to 0.050 inch, which is 36 mil to 50 mil. Every bit of that range is compliant with ASTM D3679, the standard the building code points at for vinyl siding.

Sit with that for a second. A panel at the thin end of the range and a panel almost forty percent thicker are both "code compliant vinyl siding." So when a salesman tells you his panel meets code, he has told you nothing about which end of that range is going on your house. Thickness is not the only thing that matters, and a thicker panel is not automatically a better wall. But it is a real cost difference between two bids, and it is the one the cheap bid is least likely to write down.

Two quotes can both say "vinyl" and be pricing panels from opposite ends of that spread. Insulated panels, with rigid foam bonded to the back for stiffness and a little R-value, are a third animal again. Fiber cement splits the same way, from a primed lap plank on the low end to a factory-finished product that costs several times more. If a quote will not name the brand, the product line, and the panel thickness in a number, you cannot compare it to anything. Make them write it down. Which material is right for your house in the first place is a separate call, and our guide to siding types walks through it.

What is under the panels is where the money really moves

Everything you can see on a sample board is the cheap part. The parts that decide whether your walls stay dry are the parts that get buried, which is exactly why a fast bid saves money there and you do not notice until a wall goes soft.

The weather barrier is not an upgrade, it is the code

Behind good siding sits the house wrap, a water-resistive barrier whose whole job is shedding the water that gets past the panels. Section R703.2 of the residential code calls for one across the studs or the sheathing on every exterior wall. So a bid on a stick-framed house with no wrap line on it is not a cheaper bid. It is a non-compliant one, and the savings are coming out of your sheathing.

It is also not one-size-fits-all. Wraps are rated by how much water vapor they let through, their perm rating, and a wall in Phoenix and a wall in Buffalo need to dry in different directions. The right wrap gets matched to your climate rather than grabbed off whatever pallet is closest to the truck. A bid that reuses the torn 1990s paper already hanging on your house saved a few hundred dollars and bet your walls on it.

The flashing where the roof dies into a wall

Flashing is the quiet one. The piece that decides the most is a small diverter, set down low where a sloped roof runs into the wall beside it, and the trades call it a kickout. Its whole job is throwing runoff out into the gutter instead of down behind your siding. Here is the citation that actually binds a siding crew: section R703.4 of the residential code, the wall chapter, requires flashing at wall and roof intersections. That is on the siding permit, so nobody gets to argue it belongs to the roofer.

The specific diverter sentence is worth knowing too, because plenty of contractors get its history wrong. The 2006 and 2009 residential codes are word for word identical here and say nothing about it. It first shows up in the 2012 residential code, at R903.2.1: "A flashing shall be installed to divert the water away from where the eave of a sloped roof intersects a vertical sidewall." That language has ridden along unchanged through 2021. Two things to keep straight. The model code never uses the word "kickout" and never sets a size for one, so if someone quotes you a 2-1/2 inch minimum, that is a Minnesota state amendment and not the national rule. And your state adopted whichever edition it adopted on its own schedule, so which year applies to your house is a question for your building department.

For comparing bids, none of that history matters as much as one line item. A missing kickout does not announce itself. It just rots the wall from the inside until the drywall stains, two years after both crews are gone. Look for new flashing on the page, and if it is not there, put it there before you sign anything. What else belongs in the contract, and who eats it when a scope item goes missing, is the job of our list of the questions worth asking before anyone signs.

Rot you cannot see until the old siding comes off

On any house past about twenty years there is a real chance the sheathing under the old siding is soft somewhere: under a window, below a gutter, on the shady north wall. Cutting out and replacing that plywood or OSB is not free, and in the bad spots it tends to add somewhere in the range of $2 to $5 a square foot to a bid. A higher quote may already carry a contingency for it.

A lower quote that pretends the wall is perfect is not being more honest with you. It is pushing a near-certain cost into a change order once the wall is open, which is the exact moment when saying no costs you the most. You have the most bargaining room right now, with the siding still on the house and two bids on the table. Ask the low bidder, out loud, what happens when they find soft sheathing. The shape of that answer tells you if you are holding a real price or an opening bid.

The fasteners nobody reads

Fiber cement has to be nailed with corrosion-resistant fasteners. Section R703.3.3 of the residential code lists what counts: aluminum, galvanized, stainless steel, or rust-preventative coated. James Hardie's own installation instructions go a step further, and it is worth being precise about how far. Hardie says fasteners must be corrosion resistant, galvanized, or stainless, and that electro-galvanized are acceptable, though they warn those can corrode early. Hardie recommends hot-dipped galvanized. Near the ocean, near large bodies of water, or in very humid climates, Hardie recommends stainless. Recommends is the word they use. If you live a block from salt water and your bid names an electro-galvanized nail, that is a legal fastener and still a conversation worth having.

Vinyl is a different animal. It gets hung loose on purpose so the panel can move with the heat, and a crew that nails it tight builds you a wavy wall that shows up on the first hot afternoon. That is an install-quality question rather than a bid-comparison one, and our vinyl siding install guide covers what right looks like.

Lead paint, if your house predates 1978

This one is a scope gap with a federal rule attached, and it is the reason two tear-off bids on an old house can be miles apart. EPA calls it the Renovation, Repair and Painting rule, and under it, any contractor you hire to disturb paint on a pre-1978 house has to be an EPA Lead-Safe Certified firm. The work gets contained, with plastic sheeting running out about ten feet beyond the work area. Open-flame torching is prohibited. So is power-sanding without a HEPA shroud on the tool.

Ripping old siding off a pre-1978 wall throws paint chips and dust around by definition. So a bid that priced that tear-off as if the paint were clean did one of two things. It tested the paint and found no lead, in which case the bid should say so and you should ask for the result in writing. Or it plans to break a federal rule on your property, in your yard, where your kids play. Ask which. A crew that has to answer that question in front of you will answer it honestly, and a crew that gets cagey just told you what its cheap number is made of.

When the higher siding quote is the honest one

Sometimes the expensive bid is expensive because it is the only one telling you the truth about your house. The clearest case is matching. Siding fades in the sun, and it gets made in color lots that shift a little from batch to batch, so a new panel almost never matches an aged one exactly, even when the color name on the box is identical. If part of your siding is damaged, a crew that quotes replacing the whole wall, or all four walls, so the color runs uniform is quoting a real problem. That is not padding.

This is also the trap in an insurance claim. If a storm chews up one side of the house and your old panel is discontinued, an adjuster who only pays to patch that wall leaves you with a permanent visible mismatch. Whether your policy owes you a full, matched replacement depends on your state and on the specific wording in your policy, so read it and ask before you accept anything. For comparing your two bids, the point is simpler: a quote that accounts for matching is solving a problem the cheap one is quietly handing back to you.

Lining two siding bids up so they can be compared

Give both bids twenty minutes side by side at the kitchen table and two baffling totals turn into one clear answer. Work the list in order, and do not look at a total until the end:

1. 1Confirm the same material, in writing: brand, product line, and panel thickness as a number. "Vinyl" versus "vinyl" is not a match, and "it meets code" is not a thickness.
2. 2Confirm the same scope: tear-off down to the sheathing, or new panels over the old. Those are two different jobs.
3. 3Confirm the same coverage: walls only, or the trim, soffit, and fascia too.
4. 4Find the water-resistive barrier and the flashing on each bid. Fresh wrap and new flashing at every roof-to-wall junction, or silence?
5. 5Look for a sheathing allowance. A bid that plans for bad wood is not padding, it is planning.
6. 6If the house predates 1978, hunt for the lead-safe line. Either the paint was tested clean or the crew is a certified firm working under containment.
7. 7Divide each total by the number of squares. Siding is sold by the square, meaning 100 square feet, and pricing by the square strips house size out of the comparison so two bids can be judged on the same footing.
8. 8Hand the low bidder every gap you just found and make him price each one on paper. A cheap bid that is honest comes back complete and still competitive. The other kind starts hedging.

Where a cheap siding quote quietly cuts

A low number is not automatically a bad one. But a bid sitting well below the others got there for a reason, and it is almost always by dropping one of these from the page:

• No fresh house wrap: reusing the old barrier, or skipping it, on the wall that has to keep water out. The code requires one.
• Old flashing reused: especially the kickout down where a roofline runs into a wall, the classic hidden leak.
• No tear-off: new panels going straight over the old siding, hiding any rot instead of fixing it.
• Vague material: "vinyl siding" with no brand, no product line, and no panel thickness named.
• No sheathing allowance: nothing budgeted for the soft wood a house this age is likely hiding.
• No lead-safe line on a pre-1978 house: nothing about a paint test, nothing about a certified firm, nothing about containment.
• Trim left out: a "walls only" bid dressed up to look like a full re-side.
• No permit and no disposal line: two costs that reappear later, wearing your name.