Each common rafter span is calculated by subtracting the thickness of the ridge from the total span, then dividing the answer by two. This free roofing calculator estimates the area of a roof and the amount of materials required to replace or build said roof. Divide the rafter length by 12 of run to calculate the roof ratio multiplier. Roof cuts and rafter lengths hancocks 10th edition is a very popular, best selling book. Determining roof rafter length conversion factors for roof rafters roof rafter length cutting a rafter birdsmouth to convert rafter span to sloping distance. The roof pitch calculator calculates slope, pitch, angle and rafter lengths, based on input of rise m and run r. Roof rafter calculations are simple with our online rafter calculator that determines the number of rafters required,lineal footage, board foot of ridge and facia, and. Using the 7 inch rise table and our 15 run, the common rafter length is 17 43.
Calculate draw and print rafter dimensions with large animated interactive diagrams. Calculate the gazebo lay out, the length of the sides, the length of the the center rafter, and the length of the hips. The above spans are based on american softwood lumber standard sizes. Roof pitch calculator calculates pitch, rafter length. How to calculate roof rafter lengths carpentry tips and tricks. Rafter tools is an android app with functions to calculate complex roof framing angles that other roof framing calculators dont offer. Rafter is a sloping beam usually wood that supports a pitched roof. This calculator helps you make the rafters of the suitable sizes required for your roofing.
This online truss calculator will determine the allin cost of your truss based on key inputs related to the pitch, width and overhang of your roof. Enter the value for the roof width outside to outside in feet, inches, and fraction, inches and fraction, or use the inches box to enter a value in decimals if that is your preference. Calculate the length of a rafter from roof pitch and a length measurement. Become a faster, more accurate, and more efficient roof framer with the rafter book. If youre thinking about replacing your roof with a new one, you will need a roof truss calculator. If slope is 4 in 12 and rafter span is 126, then sloping distance 12. Use the diagrams on this page as a reference when inputting rise and run, and while interpreting the calculated results. One might say that its a 612 pitch this is incorrect. Valley roof the valley roof option is used to calculate valleys for 90 degree intersecting roofs with equal slopes and wall plates at the same height. Nov 09, 2012 121 responses to common rafter framing bill bartlett november 9, 2012. For larger roofs though, i use a roofing ready reckoner. Having fixed the rise and run by the square for the common rafter, take 17 in. Common rafter length spreadsheet framing contractor talk.
If you add an eaves overhang dimension then the amount the rafter sticks passed the wall will be added to the rafter length. All you need to know are the span of the building and the slope of the roof. Roof pitch calculator use this calculator to calculate roof slope, roof pitch, and common rafter length. For many people, working out the roofs rafter length can be a bit of a nightmare. Roof framing geometry kernel rafter lengths roof ratio multiplier. Includes result for hipvalley factor, slope factor and the roof slope in degrees. How to calculate the length of roof rafters captioned. This is the rafter length from the top cut to the seat plumb mark. You might need a long tape measure to get the span, then. A rafter that runs from a hip rafter to a valley rafter, perpendicular to the roof ridge dormer rafter. My swanson speed square book will pretty much give all the lengths i need on the job. Calculate the length of a rafter from the roof slope ratio of inches per foot, and a building width measurement. Excellent tool for builders framers roofers to calculate roof rafter length, cost and number of rafters needed for the job.
These are used in almost every roof, including a gable end roof, lean to roof and hipped roof as well. If you are making repairs to your roof or installing a completely new roof, you will need a rafter calculator to help you figure out rafter lengths. Includes result for hipvalley factor, slope factor and the roof angle in degrees. Use our online rafter length calculator to quickly compute the length of the shed roof rafter by entering the measurements of overhead, length of roof span, pitch or angle. The complete pocket reference to roof framing 2nd edition barry d.
Surveyors and structural engineers utilise data from tables below to help calculate the correct size, strength and centres of roof timbers for the required spans and loadings. The common rafter length can be calculated by the roof ratio length per 12 of run. The hip rafter pitch is the common rafter pitch over in, like 8inin for an 8in12in roof pitch. Measure back 57 to form plumbcuts, giving rafter top length of 2466. The tail or eave overhang must be added to the rafter length. The difference in length of the rest of the jacks is. Roof pitch calculator calculates pitch, rafter length, angle and.
This 88page pocket size edition is in metric, updating all the old calculations, and it is a very easy. Use these two tables for roof rafters with a slope of 3 in 12 or less. Rafter span tables use these tables to determine lengths, sizes and spacing of rafters based on a variety of factors such as, species, load, grade, spacing and pitch. Large illustrations and simple formulas chop every roof framing problem down to size. Visit the roof framing page for more information on cutting roof rafters, and visit the roof pitch calculator for determining rafter lengths based on rise and run. Today, i use a calculator to find rafter lengths and angles. Hip roof framing rafter cut angle template diagram. This is especially the case if you are going to do it yourself and try to manage it all on your own. Used by carpenters union apprenticeship programs from hawaii to new york.
Maximum span calculator for wood joists and rafters. This is the complete guide to framing any gable, dutch, tudor, california, gambrel, shed or gazebo roof including irregular roofs that can stump even experienced roof cutters. The word pitch is often misused, as in this and many other articles. Sep 03, 20 shiften or swansons blue book richard birch and i are having a discussion on shiften. Easily move materials across solid or soft surfaces these carts are constantly in use in our shop. Span calculator for wood joists and rafters also available for the android os. Measure shortest jack first usually running next to a ceiling joist, from plate to hip rafter. If it was an app i might be able to use on my blackberry i might see some benefit from it. How to calculate rafter lengths for gable, hip and valley.
Includes result for hipvalley factor, slope factor and. Overhang the overhang should be measured from the outer edge of the exterior wall to the furthest point of the rafter. Print full scale rafter plumb cut templates and birdsmouth templates fold template over rafter to mark or cut through. When building a roof, how do you calculate the length of the rafters. Hes proclaimed for years that the best method for finding the correct lengths for hip rafters and laying out the back bevel angles, hip rafter side cut angle, was in the swansons blue book that you get when you purchase their speedsquare. Based on the width of the gazebo and the pitch of the roof. They made it seem effortless to cut and fit roof rafters with only the aid of a framing square. Measure the rafter length along top edge of rafter. The full version allows you to design beams of any size.
Roof cuts and rafter lengths by hancock boffins books. Click the button to calculate the stock size needed for this job. Naturally, this does not go down particularly well without the right tools, knowledge and assistance. This calculator will also calculate the king post radius,the king post rise, the king post minimum height and the octagon hip rafter to king post length. The other thing youll need is the roof pitch angle. The roof framers field manual has every trick in the book. Rafter line length calculator deduct half the thickness of the ridge from the span length this length is the correct measurement from the top plumb line to the birdsmouth plumb line. This calculator is to be used as an estimating tool only. The hip rafter angle is not the same as a 90 plan angle.
The blind valley roof can be used to calculate valleys for roofs with unequal slopes. A ready reckoner is pretty much a rafter length calculator a book full of tables for working out the rafter. Online tools for commercial and residential framing. The beam span length is fixed for this demo version. Hes proclaimed for years that the best method for finding the correct lengths for hip rafters and laying out the back bevel angles, hip rafter side cut angle, was in the swansons blue book. Jan 20, 2018 in this video, i will look at how to calculate the length of a rafter. How to figure rafters in the field or draw them in sketchup duration. Span calculator for wood joists and rafters available for the iphone. Use these two tables for roof rafters with a slope greater than 3 in 12.
Rafter tools for android apps calculator octagon roof framing. Gambrel roof a gambrel or barn style roof is simply a gable roof with a change in slope partway up the roof. Calculations for roof frames, roof cuts and rafter lengths. I put every framing situation i could think of in this book. A rafter that runs from the top of the wall plate to the roof ridge. Aug 14, 2015 it seems that most of the others used a rafter length book, or some sort of book reference, to get the length of rafters, jack rafters, etc. How to calculate the length of roof rafters captioned youtube. Roof rise this should be calculated from the base of the roof to the highest point of the roof gable the peak.
The heel height, overhang, and ridge and fascia boards for both roofs will be the same. The proper term for expressing the roof angle is slope in that instance. Rafter span tables for surveyors roof construction right. You wont find a book which explains complex roof scenarios in an easier to understand way. Our roof rafter calculator tools are handy for calculating the number of rafters needed, rafter length calculator, lineal feet of rafter, board feed in ridge and subfacia,and the total board feet in the roof. The complete pocket reference to roof framing 2nd edition. Input the rafter span on the flat, eave overhang and pitch of the roof.
It will help you with plumb and side cuts for hip and rafter, down and side purlin cuts and more. Shiften or swansons blue book richard birch and i are having a discussion on shiften. Besides its unique appearance a gambrel roof also serves to maximize the usable floor space in the attic area. The roof framers field manual blue palmetto home inspection. Calculating common rafters with a construction calculator is fairly easy, but to be a master carpenter you need more roof framing angle information then the construction calculators offers. Print full scale paper templates cut and fold over wood to mark and cut angles birdsmouth templates set bevel gauge from this page with your phone.
A rafter that sits on top of the main roof without cutting into the main roof. Calculate the length of common rafters with this free and easy online tool by entering a dimension for the roof width, selecting a pitch for the roof, and the. Sep 22, 2016 when building a roof, how do you calculate the length of the rafters. You are ready to setout and cut the common rafter lengths as soon as the wall plates have been squared, levelled and fixed strapped down onto the brickwork. A modern handbook for roof framers by david mahin mcintire. Irwin rafter square reference guide complete instruction book. Im curious about the usefulness of an excel formula for this. Rise and run means that a 612 pitch roof has 6 of rise vertical for each foot of run horizontal. Roof rafter calculator estimate rafter length, cost and. Stair tangent for iphone this iphone app is for rough frame carpenters that dont build stairs everyday, but could use an stair app calculator to check their stair building calculations. Once you know the appropriate lengths, you will be able to determine the total cost of your roof project. How to calculate your rafter length with roofing megastore. Explore a number of housing related calculators, as well as hundreds of other calculators covering topics such as finance, math, health, fitness, and more. For example, this rafter would be used when remodeling or adding on to an existing structure.
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