Our Method

Ask three contractors to price the same sunroom, and the quotes can come back several times apart. Rafter Lane gives you a range to hold them against. Every cost range on this site shows its sources and the month they were collected, and this page explains how we build it.

Who runs Rafter Lane

Rafter Lane is one person, Onur T. I collect the quotes and prices behind the tables, make the drawings and check every page before it goes up. Where the site says “we”, that’s me.

I’m not a contractor, and I don’t sell, install or recommend anyone who builds these rooms. Ads pay for the site. Contractors and manufacturers pay nothing here, and no page passes your details to them, so no one gains from a range looking higher or lower than the quotes show.

Where the numbers come from

Every cost table draws on two public sources:

• Contractor quotes homeowners post. People share the quotes they got in forums and online communities, often with the room size and their state. We log each one with its price, room size in square feet, state, type of company (local contractor or national brand), type of room, what the job covered, date and a link to the post.
• Manufacturer and retailer list prices. Published prices for room kits, windows, wall panels and equipment such as mini split heat pumps.

A list price alone is a catalog, and a single quote is one person’s story. Together they show what the materials cost and what contractors actually asked to install them.

Some numbers never go into a table: figures from other cost-guide websites, results from online estimators and numbers generated by AI tools. When we don’t have enough data, the table says so.

How we build a range

• Price per square foot first. Rooms come in very different sizes, so the main range is in dollars per square foot. Next to it is a total for a room of the median size among the quotes that gave one.
• “Most quotes” range. We sort the quotes by price and set aside the lowest 10% and the highest 10%, rounding down: 21 quotes lose 2 from each end. With fewer than 10 quotes, we set none aside. The table also shows the full range, lowest to highest.
• Unusual quotes stay in. A quote far above or below the rest stays in the table, marked. The same rule applies to every table, so no one picks which quotes count.
• What we leave out. Quotes for a different job stay out. Quotes without a room size can’t go into a per-square-foot range. The note under the table counts both.
• Thin data. With no quotes, the table says “no data”. With 1 to 4, it lists each quote on its own and marks it. A range needs at least 5.
• Job scope. A “conversion” can mean new glass only or a full tear-down, so we split rows by what the job covered. A quote that doesn’t say goes in as “scope unclear”; we don’t guess its row.

The note under every table

Every cost table ends with a short note headed “How we got these numbers”. It gives the number of quotes (local and national counted separately), the number of list prices, the month we collected them, the revision number and what we left out. The note is part of the table, and an ad never sits between the two, so the evidence stays next to the number it backs.

Why the ranges are wide

A wide range is what the quotes actually show. Each cost page explains what drives the spread in that case, such as who builds the room, how much of the existing structure stays and what the price includes. One average would hide the thing you need most: a way to tell whether your own quote is high, low or normal, and why.

Dates and updates

Every table shows the month we collected its data. We refresh tables about once a year. Each refresh or correction raises the table’s revision number (Rev. 0, Rev. 1 and so on), and the note says what changed. The date at the top of a page shows its last update.

Drawings

We draw the section drawings and diagrams in code from manufacturers’ published installation guides and spec sheets, and name the source under each one. They show which layers a room has and what each step adds. They aren’t to scale and aren’t construction plans.

Images

The room photos on idea pages are AI concept images, each labeled “Concept image”. They show what a room could look like, never a real project or what one cost. About our images explains how we make and check them.

What Rafter Lane doesn’t cover

Permits, local building codes, insurance, financing and structural engineering are set where you live and need licensed professionals there, so the site leaves them out. It also doesn’t rate or recommend contractors.

Corrections

If a number looks wrong, email [email protected] with the page and the row. If it is wrong, we fix it, raise the table’s revision number and say in the note what changed.