Barn frame

Notes

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Dimensions

Width (span)

Length

Bays

Post height

Timber size

Longest timber you can get, in feet

Interior posts under the tie beams

Back-to-back bents (a second bent right beside it)

One shared, wider post instead of two bents

Space between back-to-back bents

Knee braces (sawn from your logs)

Knee brace wood

Knee brace size

Knee brace legs

Lengthwise braces shorter by (stagger)

End wall posts to keep the end wall girt within the timber length

Girts

Plates

Plate	Top	Centerline	Underside

Heights above ground level, where the posts stand. The underside is where the posts stop; their tenons go up into the plate.

Eave joint

Tie beam drop below the plate

Roof

Set the roof pitch by

Principal queen post length

Roof shape

Roof pitch

Lower roof pitch

Lower slope width

Scarf the purlins (else one piece per bay) Queen posts Upper queen posts to fit rafters to the timber length

Principal queen post size (gambrel)

Collar drop below the rafter intersection

Join the gambrel break as an American Tying Joint

Collar to principal queen post joint (gambrel)

Garage opening

Location

Number of doors

Narrower middle door

Middle door clear width

Clear width per door

Opening height

Clear height

Header depth

Bill of materials

Member	Size, in	Qty	Centerline	With joinery	Order	Bd ft
Total

Sizes are width × depth in inches; for beams, depth is the vertical dimension. Centerline is the length in the model. With joinery is the longest the piece gets once its tenons, relish, scarf overlap or pockets are added: 4″ tenons with a ½″ housing, 2″ stub tenons at post feet, tie beams running 2″ past the posts at the eaves, plate and ridge ends to the outer face, and 3″ joist pockets. Order adds 2″ of trim and rounds up to the next 2′, but never past your longest timber; * means a piece fits with less than 2″ to trim. Board feet are for the order length. Your framer may use different tenon lengths.

Cut sheet

Tools and experience Labor rate, $ per hour (optional)

Hours per piece: about 0.4 to lay it out from its reference faces, then each end and each mortise: a crosscut 0.15, a stub tenon 0.4, a 4″ tenon 0.75, a through tenon 1.25, a seat 0.5, a half of a scarf 1.75, an English tying joint end 3, a mortise 0.8, a through mortise 1.2. These are rules of thumb for an experienced framer with power tools; the setting above scales them. Raising, finishing and handling aren't included.

Reference faceTenonThrough tenon, wedge Scarf cutSeat or lapMortise Through mortiseJoist pocketPeg

Pieces are grouped wherever every cut is the same: member, section, length, slope and the joint at each end. Chalk each group’s mark (C1, C2…) on its timbers. Lengths include the joinery, as in the bill of materials; lay out every joint from the reference faces, square rule. Tenon sizes are the customary ones; your framer may adjust them.

Site view

Turn the garage

L-shaped ranch house on the garage’s left

Space between the garage and house

Breezeway

Timber-framed breezeway against the garage’s left side, running out from it

Breezeway roof

Lean-to’s low side, toward the garage’s

Merge its roof into the garage roof (valleys where they meet)

Drop the breezeway so its roof meets the garage roof short of the purlin

Breezeway width, in garage bays

Starting at

Breezeway length, out from the garage

Breezeway post height

Breezeway roof pitch

Knee braces from logs

Member	Size, in	Qty	With joinery	Bd ft
Total

Logs and sawing

Logs, $ per bd ft of log scale Sawing, $ per bd ft of lumber Overrun (lumber per bd ft of scale) Waste, % Log small-end diameter, in Log length, ft

Brace cut sheet

Knee braces are drawn in the model but kept out of the main bill of materials, purchase list and cost; they’re listed here instead. Logs are estimated by the Doyle log rule, (diameter − 4)² ÷ 16 × length, and the overrun is how much lumber a mill gets per board foot of log scale, often 1.2 to 1.5 on small logs. Defaults are placeholders: enter your log seller’s and sawyer’s quotes.

Purchase list

Combine short pieces into longer timbers

Size, in	Length	Order	Pieces cut	Bd ft	Cost
Total timbers

Pricing

Timber species and source

Timber, $ per bd ft Milled lumber, $ per bd ft Over 20′ long, + $ per bd ft 10×10 and larger, + $ per bd ft Sales tax, % Delivery, $

Estimates only. Defaults come from 2026 mill listings; prices vary widely by region, grade, dryness and quantity, so enter the quotes you get. Timber means sections 6×6 and up; joists and stair parts use the milled lumber price.

Joinery and square rule guide

Rules of thumb for 6×6 to 10×10 timber frames, not engineering. For structural design, the US standard is TFEC 1, Standard for Design of Timber Frame Structures.

Square rule layout for this frame

Every rough timber is treated as containing a smaller, perfectly straight and square timber, ½″ under nominal each way. Joints are laid out to that perfect timber, never to the rough one.
Where another member joins, cut a ½″ housing down to the perfect size, so every joint fits the same way whatever the rough timber’s real size or twist.
Mark two adjacent reference faces on every timber, choosing the straightest. Take every measurement from them, for example a 1½″ tenon laid out 2″ in from the reference face.
Assemble with reference faces oriented the same way (listed below), so the outside of the frame stays flat for sheathing.
Put the crown up on every horizontal member, and label each piece by its bent, side and position.

Member	Nominal	Perfect timber	Reference faces

Tenons

Thickness 1½″ (2″ for heavier frames), about ¼ to ⅓ of the member’s width, laid out a fixed distance from a reference face.
Length 4″ to 5″ into an 8″ post; a through tenon runs the full depth.
Width: the full depth of the member, less any housing or a small top shoulder.
Cut shoulders square and slightly undercut so the outer edge closes tight; chamfer the tenon end so it starts easily.

Mortises

Same width as the tenon, about ¼″ deeper than the tenon is long, so the shoulder bears rather than the tip.
Don’t remove more than about ⅓ of a post’s section at one height. Stagger mortises entering from opposite sides.
Keep mortises clear of knots, large checks and timber ends.

Housings

½″ to ¾″ deep, so the full section of the beam bears on the post, and gaps from shrinkage stay hidden.

Pegs and drawboring

Dry, straight-grained hardwood such as white oak or black locust, ideally split rather than sawn.
1″ pegs for major joints, ¾″ for small members. Two pegs in major beam-to-post joints, one in girts.
At least 2 peg diameters from the shoulder and from the tenon end (the relish).
Drawbore: bore the tenon’s hole 1/16″ to ⅛″ nearer the shoulder than the post’s hole, so driving the peg pulls the joint tight.

Scarf joints

About 3 to 4 times the timber’s depth long (24″ to 32″ on an 8×8), longer for a stop-splayed scarf.
Just past a post, where it’s supported. Never mid-span; stagger them between the two walls.
Typically four pegs, with folding wedges in a stop-splayed scarf.

General

Use one layout system, square rule here, throughout the frame.
Plan for shrinkage: green oak can shrink about ½″ across an 8″ face as it dries. Housings and drawbored pegs keep joints tight.

Joinery

Joint, and where it’s used	Qty
Total joints

Tap a joint to highlight the members it joins. These are the customary timber frame joints for each connection. Pegs are usually drawbored hardwood; your framer or engineer sets peg sizes, tenon lengths and any steel.

File management

Open design file