Gable, gambrel, hipped, mansard, monitor and monoslope, named the way the trade names them. It knows post-frame because post-frame is all it does — so each shape branches the whole build: wall heights, trusses, purlins, steel, trim, the checks and the order. Roof shape and roofing product are two separate choices — a standing-seam gable and a shingled gable are the same shape.
Also called: roof types · roof styles · NFBA roof shapes · gable gambrel hip mansard monitor monoslope
Six roof shapes, each modelled rather than relabelled
Gable, gambrel, hipped, mansard, monitor and monoslope, under the names builders use for them. Each one branches the whole build: wall heights, trusses, purlins, steel, trim, the checks and the order. All six are drawn and counted — none of them is a gable behind a different name.
Software that offers one roof and a dropdown of names prices a monitor barn like a gable. The shape changes the material count, the labour and the price — a tool that only renames it hands you a quote that is wrong in a direction you discover at the yard.
The customer who wants a gambrel or a monitor barn gets quoted that building, not an approximation. The shape changes the material count, the labour and the price, so it has to change the model.
Shape and roofing product are two separate choices
Try itA standing-seam gable and a shingled gable are the same shape. Pick the shape, then pick the product — ribbed steel, corrugated, lap-sealed, snap-lock, mechanical standing seam or shingles — and the panel count comes from that product's own coverage width. Standing seam skips the screw count and adds seam clips. Shingles are bought by the square and bring a deck line with them.
A tool that lists “standing-seam gable” as one roof can't quote a standing-seam hip, and the builder ends up pricing the combination by hand.
The rep can sell standing seam on a gable or shingles on a hip without the estimate falling apart. Panel count comes from the product's own coverage, so changing the product re-counts the roof instead of renaming it.
Each shape brings its own trim onto the order
Try itA hip gets hip caps and a mitred eave frame in place of rake trim. A gambrel gets a bent cap where the pitches change. A mansard gets curb trim right around the break. A monitor gets headwall flashing where each wing roof dies into the clerestory, billed by the run. These are exactly the pieces that go missing when a shape is quoted off a gable template.
A hip quoted off a gable template arrives with rake trim it can't use and no hip caps, and the second trip to the yard eats the margin.
The trim that goes missing is the trim nobody counted — so the model counts it. Each shape brings the pieces only it needs, and the order has them before the crew asks.
Span ceilings for the shapes that have them
A gambrel runs from 20 foot, typical to 48, with a hard ceiling at 60 — and in between it is flagged special order rather than refused, because a 54 foot gambrel is a real order that just is not a stock one. A hip caps at 70 foot and needs a plan at least as long as it is wide. Past roughly 40 foot of span a single-slope truss gets deep enough at the high end to be engineered territory, and it says so before you quote it.
A span the truss plant only builds as a special order gets sold at a stock price, and the difference comes out of the builder's pocket.
The owner prices a special-order truss as a special order, before the customer signs. Refusing a 54′ gambrel would lose a real job; flagging it keeps the job and the margin.
A single-slope back wall stays a wall, not a cliff
The eave height you name stays the low eave, and the high wall follows from it — on a 30′ wide building with a 12′ eave at 4/12, that is a 22′ high wall, and it raises the tall-wall note about knee bracing. Pitch tops out at the trade's 4/12, and no combination can push the high wall past what anyone builds. The high side gets eave trim in place of a ridge cap that does not exist, and the corner trim runs all the way up.
A single-slope roof drawn from a pitch and a width turns the back wall into a cliff, and the posts and bracing it needs never make the quote.
The estimator sees the 22′ wall before the customer does, and prices the posts and bracing it needs. The high wall decides posts, steel lengths and bracing, so the model owns it instead of leaving it to arithmetic.
A monitor barn is three roof systems, and it counts all three
A raised centre gable standing on full-height interior columns — not stub posts on the wing trusses — with clerestory walls between the roof levels. The panel shows the three numbers that define it: centre width, clerestory height and wing pitch. The order gets what only a monitor needs: clerestory wall panels for both risers and headwall flashing where each wing roof dies into the riser, billed by the run. Those interior columns get the same footings and poured collars as the wall posts.
A monitor barn quoted off a gable template is missing the clerestory walls, the second roof level and the flashing where the wings meet the riser.
The builder can quote the monitor barn a customer saw on a farm, with every roof system counted. A monitor is three roof systems, and missing one is the kind of mistake that shows up as a second truck.
Right-click the roof
The roof menu is on the roof. Right-click it and the options that apply are there — gutters and roof insulation with their prices, the six roof shapes and the roofing systems with their minimum slopes — instead of hunting a settings panel for the control that belongs to what you are looking at.
Changing a roof means leaving the drawing, finding the right panel, and coming back — so it does not get changed live in front of the customer, and the 'what if we went a foot higher' conversation happens over email three days later instead.
The rep changes the roof while the customer watches, and the sale happens in that moment. Anything that makes him break eye contact to find a menu costs him the conversation.
- 1Pick the shape from the panel or by right-clicking the roof.
- 2The whole building rebuilds around it — wall heights, trusses, purlins, steel, trim and the order.
- 3The shape's own numbers appear with it: a mansard break, a monitor's centre width, clerestory height and wing pitch — each with its own arrow on the model.
- 4Each shape's limits come with it: a monoslope's pitch stops at 4/12, a gambrel's span stops at 60′, a hip stays at least 3/12.
Roof shape and roofing product are separate decisions — a standing-seam gable and a shingled gable are the same shape — and collapsing them into one list means a builder cannot price the combination they actually sell. So the two are chosen independently, and every shape is modelled for real: its own trusses, its own trim, its own limits. A picture that quietly disagrees with the material list is worse than no picture at all, so a shape is only offered as drawn once the engine draws and counts it.
- Design tools that only model one roof shape.
- Selling a shape the estimating tool silently prices as a different one.
Gable
Common trusses at your spacing with gable trusses at each end, 2x4 purlins laid flat, and rake and eave overhang framing. Steel on both slopes, ridge cap, rake trim on all four edges, and eave trim on both sidewalls.
Monoslope
Single-slope trusses or rafters running low wall to high wall, taller posts on the high sidewall, and no ridge. The eave height you name stays the low eave; the high wall follows from it. Single-slope steel, high-side eave trim, low-side eave trim, and rake trim on both ends.
Gambrel
Gambrel trusses with four chord segments breaking at the pitch change, purlins per face, four steel faces and a bent cap where the pitches change. The pitch you set is the upper slope; the steeper lower slope follows from it, held inside the band the truss plants actually build.
Hip
Commons mid-run, step-down trusses in the hip zones, and a king common at each end for the hip rafters to die into. Jacks on both the side and the end planes, so the corner purlins land on something. All four fascias are cut as one mitred frame, so the eave line closes at every corner.
Mansard
A hip and gambrel hybrid. Steep lower faces from the wall line up to a break, set in three to eight feet, with curb trim right around the break, then a shallow hip over the deck. The bent is a portal frame: bottom chord, two knee walls at the break, a collar tie across them, and the upper triangle hanging off the collar.
Monitor
Three roof systems in one building: a raised centre gable and two wing sheds, with clerestory walls between the roof levels. The classic barn configuration is wing, centre, wing — so the centre bay runs a quarter to a half of the span and the clerestory riser sits between 2 and 10 feet.
Bird's beak and flying gable overhangs
Two overhang styles on top of the standard straight rake. A bird's beak — also called a widow's peak or a turkey tail — angles the rake out to a point over the upper slope. A flying gable grows the overhang all the way from the eave. Each adds a triangle in each roof plane at each gable end, flush with the steel, plus edge trim following the new profile.
Roofing system with its minimum slope enforced
Six roofing products, each carrying its own minimum slope, a real profile referenced to a named manufacturer product, and its own fastener package. Pick the product and the picture, the panel count and the checks all follow it.
