Calculators

Every calculator in the library in one place. Each one starts on a real Modern Monticello build, so the first thing you see is the chapter's own worked answer. Change any number to test your own, and print the result as a one-page worksheet.

← Technical Library

These are worked examples, not stamped engineering designs. Each calculator says what it leaves out, and anything marked example or provisional is a placeholder, not a measurement of your material. Anything that could hurt someone if it fails deserves a licensed engineer's review.

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Showing 24 of 24 calculators.

Wood: beams, posts and joints

Bending, shear, sag, bearing, buckling, and the bolts and lags that hold it together.

Roof beam bendingHibbeler ch. 1
Is this beam strong enough in bending? It also finds the smallest single board, and the smallest doubled one, that passes.
Starts on the foundry roof beam.
Post buckling and crushingHibbeler ch. 2
Will a post buckle or crush under a straight downward load? (the plain Euler form)
Starts on the foundry roof post.
Post under roof weight and windHibbeler ch. 13
Does a post hold when wind pushes on its face while it carries the roof's weight?
Starts on the foundry roof post with wind on it.
Beam shear and notchesHibbeler ch. 14
Does the beam hold in shear at the support, and how fast does a notch in the bottom of the end use up the margin?
Starts on the foundry roof beam at its support.
Beam sagHibbeler ch. 15
How far will the beam sag, and does sag or strength decide the size?
Starts on the foundry roof beam as a single 2×12.
Doubling up boardsHibbeler ch. 17
What does doubling up boards buy over a bigger board, and does it matter how they are joined?
Starts on the greenhouse deck joist: one 2×10 is too weak, two pass.
Beam with the NDS adjustmentsBreyer ch. 1
How far do load duration, wet service, bracing and sharing between members move a lumber table number for the same beam?
Starts on the foundry roof beam as a 2×10 under snow.
Lag-screw jointBreyer ch. 2
How much load does a lag-screw joint carry, and does the wood tear out before the lags let go?
Starts on three 1/2 in lags in the Ogopogo joint.
Bearing on the post, and notchesBreyer ch. 3
Is there enough wood bearing on the post, and what does a notch (bottom or top) do to the beam end?
Starts on the foundry roof beam on a 4×4 post.
Wood column, NDS rulesBreyer ch. 4
How much load can a post carry once the NDS column stability rules are applied? This is the stricter, realistic version of the buckling check.
Starts on the foundry roof post.
Posts and timbers, fire tower legBreyer ch. 5
The same NDS column check for 4×4 up to 8×8 posts and timbers in six grades.
Starts on a fire tower leg.
Bolted connectionBreyer ch. 6
How much load does a bolted joint carry, wood to wood or wood to a 1/4 in steel plate, and is that enough for the roof's uplift?
Starts on the foundry roof's through-bolt against about 450 lb of net uplift.
Braces and washersBreyer ch. 7
How much can a brace press into a post at an angle to the grain, and how much can the wood under a bolt washer take?
Starts on a fire tower brace into a 6×6 leg, and the roof hold-down bolt.

Wind, soil and walls

What the roof, the ground and the water do to a build.

Wind uplift on an open roofHibbeler ch. 3
How hard does wind try to lift an open roof off? (the order of magnitude, not a code value)
Starts on the foundry roof in Charleston, WV.
Gabion terrace wallHibbeler ch. 4
Will a wall of stacked wire baskets tip over or slide?
Starts on the terrace wall at a 1.5 ft basket depth.
Soil under a heavy thingHibbeler ch. 9
Is the ground under a pad strong enough for what sits on it?
Starts on the Snawfus Hearth on a 5 × 6 ft pad.
Water wall: the cisternHibbeler ch. 10
Are the wall and its steel strong enough for the water depth?
Starts on the Uktena cistern at 4 ft of water.
Water wall: the hot tubHibbeler ch. 11
Are the wall and its steel strong enough for the water depth?
Starts on the Ogua hot tub at 2.5 ft of water.

Materials, shafts and heat

What the steel and the brick are actually made of, and what your tests say.

Round shaft in torqueHibbeler ch. 16
How thick must a solid round shaft be for a given torque, or how much torque can the shaft you have carry?
Starts on nothing yet: it is waiting on the paddle wheel's real motor torque and shaft diameter.
Tensile test readerCallister ch. 1
From a pulled sample's load and extension readings: what are the stiffness, yield strength and ultimate strength, and what shaft stress does that allow?
Starts on a made-up example curve, not a real test (paste your own).
Cube and beam test resultsCallister ch. 2
What design strength do your cube, beam and splitting tests give? The rule is the lowest 28-day cube ÷ 4.
Starts on example numbers at the published low end, not test results.
Compression-to-tension checkCallister ch. 3
Does your mix follow the rule that compression is about 8 to 10 times tension?
Starts on example numbers, not test results (paste your splitting test).
Rebar and brick sharing a loadCallister ch. 4
How do grouted rebar and brick share a straight-down load, and how stiff is the pair?
Starts on the Uktena wall with an example load, not a design load.
Heat growth and locked-in stressCallister ch. 5
How far does heated metal or brick grow, and how hard does it push if it cannot?
Starts on a 10 ft steel member heated 300°F.