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Two quotes. On the table. One for $28,000. One for $95,000. Both 12×12.

The homeowner asked whether the whole industry is this dishonest.

I told him to go through the cheap one and look for three words: insulation, HVAC, permit. He looked for a while and said none of them were there. There it is. The cheap quote is really just a screen box with a nicer name. The expensive one is a room attached to a house. Comparing those two is like comparing a tent to a house.

Sunroom cost by type has an order to it. Fix the type first, then talk money. Until the type is set, sunroom addition cost per square foot is a number anyone can make up. Any number is technically correct.

Sunroom Cost by Type & Realistic Budget Planning Guide

Five Things, Five Prices

A Screen Room

A screen room consists of a frame and mesh. It has no insulation and no heating or cooling—warm-weather use only. Budget somewhere between $15,000 and $40,000. Prefab kits sit at the bottom of that range; site-built versions climb as soon as a deck or slab enters the picture. There’s nothing wrong with that; it’s simply a different product.

A Three-Season Room

A three-season room is what most people actually want. It has an aluminum frame, glass walls, and a solid roof, but no insulation and no dedicated heat. Most markets: $20,000 to $55,000. Custom work in a high-cost city can hit $90,000. It is comfortable spring through fall, and it doesn’t pretend otherwise in January. If you can live with “storage room from November to March,” this is the best value on the board.

A Four-Season Room

Builders construct a four-season room to residential standards: thermally broken frames, Low-E glass, insulation, and an HVAC connection. Expect $35,000 to $100,000, with integrated custom work running higher. Every dollar over a three-season room buys something specific—insulation, mechanical extension, code-compliant wiring, better glass. None of it shows up in kit advertising. That is why you can never take a kit price and compare it against a real four-season cost.

Conservatories and Glass Solariums

Conservatories and glass solariums sit at the top. They have glass walls, a glass roof, curved or segmented geometry, and the structural work that holds that roof up. Budgets run from $35,000 to $150,000 and beyond. The premium reflects fabrication and structural labor, not branding.

One Question Filters Half the Options

Will you use this room in January?

No. Then choose three-season, and don’t overthink it. A four-season room is money spent on capacity you won’t touch four months a year.

Yes. Then skip three-season entirely. If you retrofit insulation and HVAC into an uninsulated shell later, it costs far more than building them in from the start—and many structures can’t take that retrofit at all once they’re up.

Screen rooms only make sense in one situation: airflow is the whole point and winter isn’t in the plan. Glass solariums are an architectural decision first, a budget decision second. Get that order backwards and you’ll regret it.

Getting this wrong is the most expensive mistake in sunroom budget planning. Change the type, and foundation, glazing, insulation, and mechanical scope all change with it. A lot of people build budget spreadsheets backwards from a total price. That is the wrong direction.

Sunroom Cost by Type & Realistic Budget Planning Guide

The Most Expensive Lines Are the Ones Not Written Down

Foundation

Builders usually give foundation one line on a quote, if that. But what’s under your feet decides whether this item is a few thousand or fifteen. A solid poured deck already there makes life easy. A slope, or soil that turns to soup half a meter down, isn’t a matter of paying more—it’s a matter of redesigning. A 12×12 room runs $3,000 to $15,000 on foundation alone, depending on what the excavator hits. Kit ads don’t mention it because kits don’t include foundations. Anyone actually building a room looks at the ground first.

Glass

Glass is the line most likely to jump in a four-season build. Go from standard double-pane to Low-E triple-pane, 200 square feet, and several thousand dollars are gone. Want floor-to-ceiling? Fine, the glazed area you’re specifying just doubled. I’ve seen plenty of people lock in a rendering and then ask what the glass costs. By then changing the design is awkward and expensive. So settle the spec first, and look at the pretty pictures second. Don’t do it the other way around.

The Roof-to-House Connection

The roof-to-house connection is the most overlooked and most critical part of the whole job. How the flashing runs, how the ledger attaches, how the new roof ties into the old one—technically the hardest piece, and the easiest for a proposal to skip in a single line. Some bids don’t mention it at all. If a bid doesn’t mention it, you still need it. It means when the crew shows up and starts asking questions, you’re staring at a change order and you’re not the one setting the price.

HVAC and Electrical

HVAC and electrical vary a lot by type. Three-season rooms are simple—a few circuits, some outlets, maybe a ceiling fan. Four-season rooms aren’t: dedicated circuits, insulation that has to coordinate, and ductwork you either extend or a mini-split you add. Rough-in alone runs $1,500 to $8,000 before equipment. Want to tie into the existing system? First check whether it has capacity left. If it doesn’t, you’re buying a separate unit, and that’s another number entirely. The U.S. Department of Energy’s sunroom guidance covers how glazing and thermal performance affect year-round use—worth a look if you’re weighing a mini-split against ducted extension.

Sunroom Cost by Type & Realistic Budget Planning Guide

Don’t Compare Totals

Five Buckets, Not One Total

Two totals side by side read as nothing. It’s the easiest mistake to make when comparing bids, and the easiest to fix.

Split the budget into five buckets:

1. Base and site prep
2. Frame and roof
3. Glazing
4. HVAC and electrical
5. Finishing plus contingency

Then line the quotes up and read them row by row.

What the Cheaper Quote Misses

What you’ll find is the cheaper quote usually isn’t missing price. It’s missing scope. It has no roof connection. It lists glass as “standard configuration”—standard by whose definition? It describes electrical as “basic wiring”—basic to what extent? That’s not a cheaper bid; it’s an unfinished one. A quote worth comparing will spell out how far the foundation goes, what the glass specification is, what the electrical work covers, and which HVAC route it proposes. A contractor who won’t break it down that way has already answered a question you didn’t ask.

The Unit-Price Trap

And that $80 to $400 per square foot range? It looks hard to believe until you remember people call both a screen room and a four-season room a “sunroom.” Three times the price is normal. So fix the type first, and the number starts to mean something. The range isn’t the problem. The problem is someone taking a screen room unit price and applying it to a four-season plan. The quote says “sunroom,” you assume it’s the one you want, and somewhere in the fine print the specs tell a different story. Therefore, don’t rush the unit price comparison. Ask what configuration that price actually covers.

Sunroom Cost by Type & Realistic Budget Planning Guide

Where Kanod Fits

Between a well-specified three-season room and a custom four-season build, there’s a gap worth thinking about. Frame and glass are the part you can actually control.

Kanod’s aluminum systems use thermal-break profiles and accept double-pane or Low-E glazing. You select the frame-and-glass package against your climate and budget rather than accept a single fixed package. If you’re comparing framework and glass across several bids, the aluminum sunroom systems and thermal-break window range provide a baseline. Before labor and site work come in, you should know roughly what that portion is worth. That way, when you sit down with a contractor, a vague “standard configuration” line item won’t get past you.

At the end, a sunroom budget you can trust passes a simple test: it names the type, accounts for the site, and breaks out the five cost categories. If yes, the quotes become comparable. If not, the lowest number is just a starting point—and what comes after it is anyone’s guess.