A double gable roof joins two gable sections side by side so the finished roof reads as an “M” when you look at it head on. The two ridges run parallel, and where the inner slopes meet they form a single central valley that runs the length of the house. The term also gets used a second way, for a facade with two front facing gables, so the first job on any plan or quote is confirming which one you mean.
This guide covers both meanings, how a double gable differs from a cross gable, why the central valley decides whether the roof leaks, what it costs against a plain gable, and when the shape is worth the extra complexity.
What is a double gable roof?
A double gable roof is two parallel gable roofs built next to each other and tied together at a shared central valley, giving the roofline an M profile from the gable end. Each half has its own ridge and its own pair of slopes. The design lets a wide building keep a normal roof pitch without pushing the single ridge impractically high, which is its main structural reason to exist.
The same name is applied to a different thing: a house elevation with two gables facing the street, sometimes called a twin gable or double front gable facade. That version is about curb appeal and symmetry, common on Craftsman, Victorian, and modern farmhouse designs. It may sit on top of a roof structure that is not itself M shaped. When someone says “double gable,” pin down whether they mean the M shaped roof structure or the twin gable elevation before pricing anything.
Double gable vs cross gable vs Dutch gable
A double gable uses parallel ridges and one central valley. A cross gable uses ridges that intersect at an angle, usually 90 degrees, creating valleys where the wings meet. A Dutch gable stacks a small gable on top of a hip. These are separate shapes that solve separate problems, and they are priced and flashed differently.
| Roof shape | Ridge layout | Valleys | Best for |
|---|---|---|---|
| Standard gable | One ridge | None | Simple rectangular footprints, lowest cost |
| Double gable (M shape) | Two parallel ridges | One central valley | Wide spans that need to keep pitch and ridge height in check |
| Cross gable | Two or more ridges intersecting, often at 90 degrees | Multiple valleys at the wing junctions | L shaped and T shaped floor plans, attached wings |
| Dutch gable | Gable set above a hip | Hip lines, no interior valley by default | Extra attic light and volume with hip style wind behavior |
The practical split: if the two ridges run the same direction, it is a double gable. If they cross, it is a cross gable roof. Both create valleys, but the double gable has one continuous valley down the middle rather than several short ones at intersections.
The central valley: the part that decides whether it leaks
The central valley is the single most important detail on a double gable roof, because two roof planes drain into one channel that carries roughly twice the water of a normal slope. If that channel is undersized or poorly flashed, it is the first place the roof fails. On the M shaped configuration the valley runs the full length of the ridge, so any weak point has a long path to find.
Two ways to build it:
- Open metal valley. A wide metal liner (commonly 24 inch or 36 inch W valley or a center crimped valley) runs under the shingles or panels on both sides, with the roofing cut back off the center. This is the standard detail for shingle and most metal roofs and sheds water fast.
- Valley gutter (internal box gutter). On wide or low pitch spans, the center becomes a lined internal gutter with its own outlets and downspouts, similar to a roof valley flashing detail scaled up. This needs positive slope to drains and is the version most prone to ponding if it is built flat.
Practical rules that keep a central valley dry: run self adhering ice and water membrane the full length of the valley before the metal goes down, lap shingles or panels a consistent distance off center, and never let a nail penetrate the drainage path. In snow country the valley also collects sliding snow and ice from both slopes, so ice and water protection and adequate outlet capacity matter more here than on a plain gable.
Pros and cons of a double gable roof
A double gable roof buys usable interior volume, natural light on two ends, and strong curb appeal, at the cost of a central valley that adds construction complexity and a lifelong maintenance point. The trade is volume and looks versus the extra risk and cost the valley introduces.
Pros
- Keeps a normal roof pitch across a wide footprint without an extreme ridge height.
- Two gable ends allow large windows, gable vents, and good daylight and ventilation.
- Steep slopes shed rain and snow well off the outer faces.
- The M profile and twin gable elevation read as distinctive and add resale appeal in many markets.
Cons
- The central valley is a concentrated drainage and leak point that needs correct flashing and periodic cleaning.
- Like all gable shapes, it faces higher wind uplift than a hip roof, so bracing and connections matter in high wind zones and can affect insurance.
- More rakes, ridges, and valley work mean higher material and labor cost than a plain gable of the same size.
- Debris, leaves, and snow can collect in the valley and back water up if drainage is undersized.
What a double gable roof costs
A double gable roof typically costs more than a simple gable of the same footprint, because the extra ridge, extra rake edges, and the central valley add material and labor. As a rough planning figure, expect a premium of about 5 to 15 percent over a comparable single gable, with the valley lining and flashing being the main adder. Final numbers depend on material, pitch, region, and how the valley is built.
| Roofing material | Installed cost per sq ft (2026 range) | Notes for a double gable |
|---|---|---|
| Asphalt shingles | $4.50 to $8.00 | Add open metal valley plus ice and water membrane the full valley length |
| Standing seam metal | $10.00 to $18.00 | Valley pans and closures add trim labor at the center |
| Clay or concrete tile | $10.00 to $20.00 | Valley battens and closures raise labor on the M junction |
These ranges cover the roof surface only. On the M shaped version, budget separately for the valley system: a lined internal valley gutter with outlets and downspouts costs more than an open metal valley and is worth specifying on wide or low slope spans. Get an itemized quote that names the valley detail rather than a lump sum, because that line is where double gable bids differ most.
When a double gable roof makes sense
A double gable roof makes sense on a wide or deep footprint where a single ridge would sit too high, and on elevations where twin gables carry the intended architectural style. It is a strong fit in rainy climates that reward steep shedding slopes, and a weaker fit in high wind coastal zones where a hip roof performs better under uplift.
Skip it, or design the valley with extra care, if the building sits in heavy snow country, since both slopes dump into one channel. Framing a double gable is more involved than a plain gable because the two roof systems have to align and share the valley cleanly, so review the layout against standard gable roof framing before committing. For the wider family of gable variants and where this one fits, see the main gable roof guide and the rest of our roofing basics.
Frequently asked questions
What is a double gable roof?
A double gable roof is two parallel gable roofs built side by side and joined at a central valley, forming an M shape when viewed from the gable end. Each section has its own ridge and slopes. The name is also used for a house facade with two front facing gables, so confirm which meaning applies before you plan or price the roof.
Is a double gable roof the same as a cross gable roof?
No. A double gable has two ridges running in the same direction with one central valley. A cross gable has ridges that intersect, usually at 90 degrees, creating valleys where the wings meet. Double gable suits wide rectangular spans, while cross gable suits L shaped and T shaped floor plans with attached wings.
Does the valley on a double gable roof leak?
It can if it is built wrong, because two slopes drain into one channel that carries about twice the water of a normal roof plane. Correct construction, full length ice and water membrane, a properly sized open metal valley or lined valley gutter, and clean drainage outlets, keeps it dry. The valley is the detail to inspect and clean most often.
Does a double gable roof cost more than a standard gable?
Usually yes, commonly about 5 to 15 percent more than a single gable of the same footprint. The extra ridge, added rake edges, and the central valley system drive the difference. Asphalt runs roughly $4.50 to $8.00 per square foot installed, with the valley lining and flashing as the main adder. Ask for an itemized valley line on the quote.
Is a double gable roof good in high wind or heavy snow?
Gable shapes face higher wind uplift than hip roofs, so a double gable needs solid bracing and connections in high wind zones and may carry higher insurance in coastal areas. In heavy snow, the central valley collects load and meltwater from both slopes, so it needs generous ice and water protection and drainage capacity. In moderate climates it performs well.
Reviewed by The Roofing Brief Team. Last reviewed July 2026.