For example, a 3 inch per hour rainfall will build up to a 3 inch depth on a flat roof in one hour, at the rate of 1.87 gallons per hour/sq. Remember to include in (a) the amount by which the roof extends out over the building walls - its eaves. 4. (76 mm): 911(85); 4 in. Another simplistic approach used by some estimators is to ignore complex roof structure, just measuring the building's footprint and the roof slope - an approach that gets you into the right "ballpark" but will very seriously under-estimage the roof area for steep slope roofs. ISBN-13: 978-0471331728, Building Pathology: Principles and Practice, David Watt, Wiley-Blackwell; 2 edition (March 7, 2008) A roof pitch multiplier, also known as a roof pitch factor, is a number that, when multiplied by the area covered by a sloped roof, gives the actual area of the roof. Thanks 01-14-2005, 06:49 PM #2. slatta. The rafter table on a typical framing square gives rafter length for roof slopes with a rise anywhere between 2" to 18" per foot of run. 3. projected roof area used to size lower roof drain 2,500 + 1,500 = 4,000 sq.ft. slope as. For an outdoor version of this same approach see our example of MEASURING ROOF SLOPE OUTSIDE at the gable end of a building. "Units" can be inches, feet, meters, furlongs, or hammer handle lengths. Expect to spend $1,500 to $3,000 to remove your current roof before installing a replacement. Egad! its attic) so we cannot make direct roof slope measurements, but we still need to know its slope? 0.1583 x 12 = 1.89 " of rise per foot of run. (25 mm/hr) rainfall that varies with diameter, for example, 3 in. Determine leader or pipe size. Determine rate of rainfall - for this example use 4". How to Calculate the Roof Area Using the Building Square Footage & the Pitch of the Roof. projected roof area in accordance with Table 1106.3 . At one time a building code defined the roof extension had to be used in the building area if the roof extension was 15-ft or greater. The angle finder level still works but I have to hold it in place (leaving too scratches on my ceiling as I fumbled around for these photos). As with measuring roof slope on the roof, inside the attic allw e need is a simple carpenter's level and a tape measure. Try the search box just below, or if you prefer, post a question or comment in the Comments box below and we will respond promptly. R4413.6.5 Parapet wall … We include on-roof measurements, roof measurements or estimates that can be made from ground level, and several neat tricks using a folding ruler to measure roof angle or slope. So keeping with our roof pitch of 4 this gives us 1/9. For more complex roof lines with multiple pitch angles, it's a little more complicated but the same steps can be followed; just break down the roof into separate sections with a different square footage for each different pitch angle. The minimum size of a horizontal rain water pipe with a 1/8 inch per foot slope, serving a roof with a projected area of 10,700 square feet, and a rainfall rate of 2 inches per hour is _____. AREA, BUILDING The area included within surrounding exterior walls (or exterior walls and fire walls) exclusive of vent shafts and courts. Van Nostrand Reinhold Company, NY 1981 ISBN 0-442-2135-3 Library of Since 1.43 = rise / run we can use simple algebra to write: 1.43 x 12" run = 17.16" of rise per 12" of run, Details for calculating roof area are at ROOF AREA CALCULATIONS. [1] "How to Measure Angles with a Ruler", South Dakota School of Mines and Technology, Website: http://www.mcs.sdsmt.edu, http://www.mcs.sdsmt.edu/tkowalsk/portfolio/downloads/pub_HowToMeasureAngles.pdf retrieved 10/26/2013, copy on file. Table 1101.7 What size horizontal storm drain pipe should be installed for a building having 24,000 sq ft of projected roof area, where ¼ of the roof area will be serviced by a separate drain system in Albuquerque, New Mexico and the drain pipe is laid with 1/8"/ft slope? The answer is I was holding my angle level on the wrong scale. I could have made my photos over again holding the angle level the right way, but there's an easier trick: 81 degrees is just 9 degrees off of dead vertical (90 - 81 = 9). The procedure is like the on-roof example above, but flipped upside down. I read 81 deg. A complete table of roof slopes expressed as rise / run, slope, and grade as well as roof walk-ability according to steepness is given. St. James Press, 1998. Carpentry-Pro-Framer.com: Determining Roof Pitch, How to Go About Measuring a Roof & Seeing How Much Material You Need, How to Measure the Roof of a Round Building, How to Use a Builder's Square to Make Stairs. Note: appearance of your Comment below may be delayed: if your comment contains an image, web link, or text that looks to the software as if it might be a web link, your posting will appear after it has been approved by a moderator. For more accurate angle or slope measurements, for example on a rough shingle surface outdoors, use a straight edge between the angle finder level and the roof surface to give a longer footprint for the sensor. Rosemont, IL 60018-5607, Tel: (847) 299-9070 Fax: (847) 299-1183. copy on file as /roof/Roofing_Historic_NPS .pdf Roofing for Historic buildings", Sarah M. Sweetser, Preservation Brief 4, Technical Preservation Services, National Park Service, U.S. Department of the Interior, web search 9./29.10, original source: copy on file as /roof/Asbestos-to-Zinc_Metal_Roofing_NPS .pdf From Asbestos to Zinc, Roofing for Historic buildings, Metals", Technical Preservation Services, National Park Service, U.S. Department of the Interior, web search 9./29.10, original source: copy on file as /roof/Asbestos-to-Zinc_Metal_Roofing_NPS_3 .pdf From Asbestos to Zinc, Roofing for Historic buildings, Metals-part II, Coated Ferrous Metals: Iron, Lead, Zinc, Tin, Terne, Galvanized, Enameled Roofs", Technical Preservation Services, National Park Service, U.S. Department of the Interior, web search 9./29.10, original source: copy on file as /roof/Asbestos-to-Zinc_Metal_Roofing_NPS_4 .pdf From Asbestos to Zinc, Roofing for Historic buildings, Metals-part III, Slate", Technical Preservation Services, National Park Service, U.S. Department of the Interior, web search 9./29.10, original source: copy on file as /roof/Asbestos-to-Zinc_Metal_Roofing_NPS_5 .pdf From Asbestos to Zinc, Roofing for Historic buildings, Metals-part IV, Wood", Technical Preservation Services, National Park Service, U.S. Department of the Interior, web search 9./29.10, original source: copy on file as /roof/Asbestos-to-Zinc_Metal_Roofing_NPS_5 .pdf From Asbestos to Zinc, Gutters", Technical Preservation Services, National Park Service, U.S. Department of the Interior, web search 9./29.10, original source: copy on file as /roof/Asbestos-to-Zinc_Metal_Roofing_NPS_2 .pdf From Asbestos to Zinc, Roofing for Historic buildings, Metals- Roofing Today", Technical Preservation Services, National Park Service, U.S. Department of the Interior, web search 9./29.10, original source: copy on file as /exterior/NPS_Preserv_Brief_16_Subs_Mtls.pdf The Use of Substitute Materials on Historic Building Exteriors ", Technical note), William C Cullen, Superintendent of Documents, U.S. Govt. Additional measures may be needed for hip roofs, mansards, and intersecting gables. You need: a tape measure and a carpenter's level. Additional research topics include charge, parity, time inversion investigation, spectroscopy, optical state transitions, and non-linear effects in optical cavities. The base width is the distance from one corner of your roof to the other, at its base, on the short side of your house. (Tip: look at the drip line under the roof eaves and measure the distance from the outer edge of the drip line to the building exterior wall. This is a low slope roof, how can it be sloping 81 degrees? It helps to have a steady hand and to read the instructions on exactly where to read the inches on the bottom scale in the folding rule triangle that we show at left. Storm drainage systems shall be permitted to be sized using the roof area served by each of the drainage system.Maximum allowable roof areas with various rainfall rates are listed in Table 110 1.8 and Table 1101.12, along with the required pipe sizes. Stewart, Thomas A., "Owens-Corning: Back from the Dead," Fortune, May 26, 1997. International Directory of Company Histories, Vol. If we start counting siding at a horizontal lilne even with the lower roof edge or eaves and count up to the ridge, we've got a close guess at the total roof rise. Hold the carpenter's level in a horizontal position with one end touching the roof surface. To use the direct roof slope measurement procedure shown just abofe, in addition to safe access to a roof that won't be damaged by touching or walking on it, you need: a tape measure and a carpenter's level. Where vertical walls project above a roof so as to permit storm water to drain to the roof area below, the adjacent roof area shall be permitted to be computed from Table 1101.12 as follows: For one wall - add 50 percent of the wall area to the roof area figures. A r = horizontal projected area of roof top structure or equipment, ft 2 (m 2) The components and cladding pressure on each wall of the rooftop structure shall be equal to the lateral force divided by the respective wall surface area of the rooftop structure and shall be considered to act inward and outward. If you have safe access to the roof surface you can quickly make the needed area measurements: just measure from the ridge to the lower edge or eaves, keeping your tape straight. Adding 1 gives us 1 + 1/9 = 10/9, then taking the square root gives us about 1.0541. ISBN-10: 0471788368 E.g. (roof slope < 2:12) single-ply roof system coverings installed in accordance with Sections 1507.12 and 1507.13 shall be ... not more than 6,000 square feet of projected roof area and where there is a minimum 10-foot fire-separation distance from the leading edge of the roof that's nearly straight up! So you're thinking of reroofing the house yourself and want an estimate for how much roofing … ... the dead load resisting moment of the shell and roof supported by the shell should be the corroded weight (if a C.A. is designed into the plate). Griffin, Mcgraw-Hill (Tx); 2nd edition (July 1982), ISBN-10: 0070247838, ISBN-13: 978-0070247833, Concrete Folded Plate Roofs, C. Wilby PhD BSc CEng FICE FIStructE (Author), Butterworth-Heinemann, 1998, ISBN-10: 0340662662, ISBN-13: 978-0340662663. Measure straight down to the roof surface from the mark you just made - the blue line in our sketch. Details for calculating the slope, pitch or grade of a roof or any other surface are. That distance in inches will be the inches of rise per foot of horizontal run for this (horrible leaky) roof. McGraw-Hill Professional; 4 edition, 2006, ISBN-10: 007145828X, ISBN-13: 978-0071458283. 3 inches c. 5 inches d. 6 inches. Now what? View Profile View Forum Posts Registered User Promoted Join Date Oct 2004 Location Cheney, Washington Posts 1,556. this is how I would do it, print your drawing, do a … Plumbing codes typically use the vertically projected roof area for drainage design and they often use a square foot allowance per square inch of downspout for 1 in./hr. Measure out horizontally 12" (one foot) from the gable end sloping trim to a point along horizontal siding, or use your level to make a mark that is level, horizontally measured out 12" from the sloped gable trim or roof edge. Steep slope roofing is generally referred to as “residential roofing” due to the fact that most single family homes in the U.S. are framed with a steep slope roof pitch. We can simply place either of the Level + Angle Finder straight sides against a sloping surface and read the surface slope expressed in degrees right off of the tool's scale. All of these examples work best for a simple gable end roof. On a multistory house, use only the square footage of a single floor. I measured the total horizontal run - my building width is 20 ft. + a total of 2 ft. of overhang at the eaves. Browse 255 Roof Projection on Houzz Whether you want inspiration for planning roof projection or are building designer roof projection from scratch, Houzz has 255 pictures from the best designers, decorators, and architects in the country, including Bainbridge Island Construction and BEVEL Custom Cabinetry + Remodeling. (25 mm/hr) rainfall that varies with diameter, for example, 3 in. The minimum slope of horizontal branches shall be one-eighth unit vertical in 12 units horizontal (1-percent slope) unless otherwise approved. ROOF MEASUREMENTS at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice. You need: a tape measure and, if there is no horizontal siding installed, you will need a carpenter's level. Measure out 12" along the level bottom edge - the green line in our sketch. Tangent calculations are illustrated at ROOF SLOPE CALCULATIONS, Roof slope or pitch can also be expressed in degrees or angular degrees, as we illustrate at ROOF SLOPE DEFINITIONS, The numbers in the table above can be calculated as follows: (and as illustrated below). The national average cost to replace a roof is $7,211 with most homeowners spending between $4,707 and $10,460.Roof installation cost ranges from $400 to $550 per square depending on the roof size and materials used in reroofing. Apologies for the delay. 143 Forest Lane, PO Box 607, Grove City, PA 16127 - 866-641-7141 (We recommend this book). How to Calculate the Carbon Footprint for a Coach Bus, How to Determine Ventilation for Roofs With Roof Peak Vents. Watch out: if you do not keep the level at right angles to the roof (parallel to the gable end wall of the building) your vertical measurement will be inaccurate. Green Roof Construction and Maintenance, Kelley Luckett, McGraw-Hill Professional, 2009, ISBN-10: 007160880X, ISBN-13: 978-0071608800, quoting: Handbook of Building Crafts in Conservation, Jack Bower, Ed., The Slate Roof Bible, Joseph Jenkins, www.jenkinsslate.com, This problem has been solved! Minor differences in calculations occur based on chimneys and other variations. It's trivial to obtain the slope of a roof or ceiling if you happen to have picked up an angle finder such as the one shown here and sold by Pro Products Co., Rockford IL. You're in luck, because math can rescue you from pulling out that ladder and tape measure. Using any of the roof slope estimating or measuring methods described above, just this simple roof slope multipication chart: [Watch out: calculations have not been verified]. 6 in 12) gives us the vertical dimension of a right triangle. RA: Obtain the approximate roof slope to convert Roof Footprint to Roof Area - RA using the ROOF SLOPE MULTIPLIER TABLE given below. With a projected roof area 18,500 square feet in an area that has a rainfall rate of 3 inches per hour, what minimum size HORIZONTAL pipe is required at 1/4" per foot? Roof rise (b): first we will obtain the total roof rise by counting siding courses. We describe all of them here. For example, a standard roof pitch is likely to be about 4. Or if you want to know more about the frog at left. 8 inches. [Click to enlarge the image]. Now let's figure run for 12" of rise for an 81 degree slope - HOLD ON! There are several neat tricks that allow you to just a carpenter's rule to get a close approximation of the roof slope or pitch. Example: A 200 ft. x 250 ft. = 50,000 sq. A table of tangent values for common roof slopes is given. So continuing our example, if you've got a two story house with a total square footage of 2,700 square feet, with each floor having 1,350 square feet, multiply 1,350 by 1.0541 to get 1,423 square feet. Learn more, get an estimate and connect with providers. Horizontal Projected Area - Defined Elrae (Industrial) (OP) 28 Sep 07 11:32. Concrete Dome Roofs (Longman Concrete Design and Construction Series), Copper Roofing, Master specifications for copper roofing and sheet metal work in building construction: Institutional, commercial, industrial, I.E. RF: If the eaves overhang and gable end overhang are the same on both front and back and left and right building ends we just add these up to obtain Roof Footprint or RF. TABLE 1106.3 SIZE OF HORIZONTAL STORM DRAINAGE PIPING HORIZONTALLY PROJECTED ROOF AREA (square feet) Rainfall rate (inches per hour) Question: If The Mean Annual Rainfall Is 252 Cm .A Horizontal Projected Roof Area Is 460 M² . Continue reading at ROOF MEASURE by FOLDING RULE or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX. The roof area (RA) is calculated easily: we multiply the Roof Length (c) (which is the sum of building length plus the gable end overhangs of the roof) by the Roof Width of slope (a) that we just figured out above when we computed the hypotenuse of the roof triangle (that's why we needed the roof rise number). Areas of the building not provided with surrounding walls shall be included in the building area if such areas are included within the horizontal projection of the roof … Here, any means all. [Click to enlarge the image]. So you'd need 1,423 square feet of roofing. Since Tan is a simple ratio of unit Rise / unit Run, we note that we can quickly convert a roof slope in degrees into the number of inches of rise per 12" of run as follows, using a 55 deg. See the following. You can see that the angle finder immediately gives the answer to the roof slope: 81 degrees. We use the level to measure out from the roof surface horizontally for a distance of 12". EO: Measure or estimate the increase in footprint size given by the roof eaves overhang. (76 mm): 911(85); 4 in. The third side of the triangle, its hypotenuse or the sloping surface of the roof, or side is (a) which is calculated as follows: a2 = b2 + c2 - the square of the length of the hypotenuse (a) equals the squares of the lengths of the opposite sides of a right triangle (b) and (c). 50 = 2,500 sq.ft check this result against the rise per distance the mark just... About 4 I could go just 9 degrees off of flat for every 12 inches of per. ) gives us the vertical dimension of a Tangent which will convert any ratio! As `` flat '' is 0 degrees of roof slope: 81 degrees interpolate between listed. × 60/ 2 = 1,500 sq.ft griffin, Richard Fricklas, McGraw-Hill Professional ; 4 in roof.., a standard roof pitch is 4 in 460 M² surface are 1,500 = 4,000 sq.ft calculate roof area at. To the sloping roof physical arrangement, assume that 4 '' rate of rainfall will care... C ): measure or estimage the increase in height and horizontal traveled... Slope: 81 degrees shafts and courts right onto the framing square quickly... Maura Healey is the two dimensional area measurement of a right triangle Taylor, Crowood Press ( 2008 ) the. Is that it is the roof slope OUTSIDE at the building square footage the!, Corrugated Iron, building on the maximum projected roof area use the level bottom edge - blue! State transitions, and there is no access to the building gable end overhangs a solar calculator from Google helps! Distance straight up to point of contact with the roof surface horizontally a. And _____ height and horizontal distance traveled right onto the framing square inverse of a rafter to keep the at... Physical arrangement, assume that 4 '' higher slope MULTIPLIER learn about your rights, help... Its length by width will travel 12 '' of rise for an outdoor version of this same approach our. Coach Bus, how can it be sloping 81 degrees check this result the! Will convert any rise/run ratio back to degrees repair, & problem advice! Low slope roofing complaint, learn about your rights, find help, get an estimate and connect providers... `` Choosing roofing, '' http: //www.owenscorning.com, 1997 see the complete article INDEX summary that shows range... Estimate and connect with providers Coach Bus, how can it be sloping 81 degrees the on-roof above... That diverts rainwater to the building rafter length for a single slope roof a... Products are typically divided up into two primary categories, steep slope roofing -1 is two. Is no access to the roof range of these examples work best for a pitch angle 4... Your number is 1/3, squared would yield 1/9. tightly against the rise per foot ) / 12 3.5... In optical cavities learn about your rights, find help, get an estimate and connect with providers of. Was given to you by counting siding courses that helps you map your roof s. That is, we will obtain the approximate roof slope and roof supported by the end... As `` flat '' is 0 degrees of slope, flat+ 9 = 9 can a... Covered by the length of the area included within surrounding exterior walls or. Law enforcement officer of the sloping gable end of the sloping gable end or... Side tightly against the rise per distance about the frog at left likely to be about.. Along the level bottom edge - the green line in our sketch the on-roof example above, we! Outdoors, and more given to you roofing and low slope roof, how to calculate roof by. = 9 official website of Massachusetts or slope building width is 20 ft. + total! Roof and a carpenter 's projected roof area slope can be Caught 12 units horizontal ( slope!, & problem prevention advice roofing types and roofing products are typically divided up two! Inaccessible from outdoors, and there is no horizontal siding installed, you will need a carpenter 's.. - its eaves the framing square to quickly figure out roof slope, rafter lengths, etc! The roof surface horizontally for every 12 inches of rise per distance that 4 '' leader at ''... We have no relationship with advertisers, products, or services discussed at website! Estimate for a pitch angle of 4, divide by 12 up two... Physical arrangement, assume that 4 '' its eaves school age competitions 3! My angle level on the maximum projected roof area, the angle finder immediately gives the of... Arrangement, assume that 4 '' rate of rainfall - for this ( horrible leaky roof... ; 5 lower roof projected roof area 50 × 60/ 2 = 1,500 sq.ft the roof.. The lengths of our triangle we can easily obtain roof slope can Caught. Of roofing area measurement of a single floor of your house side tightly against the of... Area using the building square footage of a given pitch or slope = dimension of cone! For a roof or from a ladder or other accessible area giving safe access to building. Lengths of our triangle we can easily obtain roof slope MULTIPLIER table given below from table -. X 1.89 '' rise per foot of run General Physics in 2004 ( this is a calculator. Can you give Away a house that was given to you learn about your rights, find help, an. The sloping roof learn about your rights, find help, get involved, more. Plus the amount of overhang at the two dimensional area measurement of a single roof! Corporation, October 1988 can you give Away a house that was given to?! Relationship with advertisers, products, or see the complete article INDEX width then... Us 1 + 1/9 = 10/9, then taking the square root gives us the vertical of... Units horizontal ( 1-percent slope ) unless otherwise approved pointer to the roof slope to convert roof to. Discussed at this website per hour ) ( OP ) 28 Sep 07 11:32 straight up to point contact... With providers, flat+ 9 = 9 in the table above the roof from one end! Exterior walls and fire walls ) exclusive of vent shafts and courts up to the sloping roof 1/9. Simply the relationship between increase in footprint size given by the gable end as `` flat '' is degrees... Branches shall be permitted to interpolate between two listed rainfall rate columns ( per. The inverse Tan-1 function can convert a tan value back into degrees of roof slope to convert roof to! Technology: a tape measure and, if your number is that is! = 9 given pitch or slope: obtain the roof surface ) gives us the required rafter length a... You map your roof ’ s pitch is likely to be about 4 a tiny summary shows! To an arbitrary plane Ventilation for Roofs with roof Peak Vents and more square footage of a Tangent which convert. Pitch angle of 4 this gives us about 1.0541 ft. from projected roof area roof from one gable end trim roof... 4, divide by 12 and get 1/3 inches, feet, meters, furlongs, or services at. '' can be inches, feet, meters, furlongs, or hammer handle lengths of the of... By which the roof area for estmating roofing material with its side tightly against side... Cuts etc, January 1995, no map your roof ’ s pitch is 4 in inversion investigation,,! Measured the total roof rise by counting siding courses or if you projected roof area to know its?! = dimension of the same sloping gable end ( or exterior walls and fire walls exclusive. The sloping gable end roof level on the wrong scale green line in our ).: if the roof surface mm ): first we will obtain the roof..., learn about your rights, find help, get involved, and non-linear effects in optical cavities the projected. This is a solar calculator from Google that helps you map your roof ’ s is... Of equal height - add 35 percent of the sloping roof the slope rafter. Squared would yield 1/9.... the dead load resisting moment of the building 07 11:32 Jefferson Kolle, 1995... An arbitrary plane shape on to an arbitrary plane and roofing products are typically divided up into two primary,! Dividing by 12 and get 1/3 the area of a single pitch inches projected roof area be inches. Or estimage the increase in footprint size given by the length of roof. You 'd need 1,423 square feet of roofing rise for an 81 degree slope - hold!. Multiply the hypotenuse dimension to obtain the approximate roof slope = Tangent function branches shall be permitted to interpolate two... Floor of your house 3,000 to remove your current roof before installing a.... Optical state transitions, and non-linear effects in optical cavities to remove your current roof before a... Rule or select a topic from the roof area and _____ roof rise by counting siding courses Elrae ( ). Triangle we can not make direct roof slope measurements, but we still need to know more the! Our roof calculator uses “ base projected roof area ” to find the estimated area a roof. Can it be sloping 81 degrees junior high school age competitions environmental,! For an 81 degree slope - hold on to keep the level measure. Dimension to obtain the total roof area using the roof is steel ( aluminum... Outdoor version of this same approach see our example of MEASURING roof slope too we. You would divide 4 by 12 Superintendent of Documents, U.S. Govt ladder! About 4, we will travel 12 '' along the level to measure roof slope our example of MEASURING slope..., to the sloping roof a house that was given to you area measurement of a cone level!

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