3. Measure from the top to the ground, then add 4 feet (1.2 m) to each downspout to account for the angled extension at the bottom that directs water away from the home. This article was co-authored by Barry Zakar. Size downspouts to fit the gutter. Most roofs are symmetrical so you can enter the number of downspouts attached to the surface area that you just measured. More From Doityourself . Loose-fitting pipes will leak and spread water close to the foundation walls. Hook the tape measure on one side, stretch it down the downspout and mark the measurement. Refer to the gutter packaging or specification for the recommended downspout size. Gutter downspout sizes are 3 to 6 inches. per ft., and you can multiply the watershed by 1.4. Downspout size selection. furthermore, the standard norm for gutters among many in the rain carrying industry is to allow 1 square inch of outlet opening in the gutter for every 100 square feet of roof area being drained. We know ads can be annoying, but they’re what allow us to make all of wikiHow available for free. Nan W. on Mar 27, 2018. Transfer your measurement to the downspout and make a mark on both sides with your pencil. ft. of watershed. Latest News from. A ‘Plinth Offset’ may also be needed at the bottom of the downpipe to allow it to follow the contours of the wall. Half-round gutters are round on the bottom with a lip on the top of the outside edge. The gutter outlet capacity should suit the downspout To find the right size faucet for your sink, grab a tape measure and follow these easy steps. Use your tape measure to determine the length of the twine, marking down this calculation. Related Posts. 4. The gutter and downspout size required is highly dependent on the amount of gutter and the spacing of the downspouts. Place your ladder at the corner of your home. You should have enough gutter downspouts to effectively handle the size of your entire gutter system. Measure distance from the fold of the flap to the wall. unlocking this expert answer. Use your tape measure to determine the length of the twine, marking down this calculation. Subtract 6 to 7 inches and this will become the length of the downspout. Barry Zakar is a professional handyman and the founder of Little Red Truck Home Services based in the San Francisco Bay Area. Match your downspouts to the gutter size you chose in Step 7. The size of the downspout should be constant through-out its length. Fourth: We'll discuss your downspout size, location and a few comments. Barry Zakar. With over ten years of experience, Barry specializes in a variety of carpentry projects. spout drains up to 600 sq. For a 5" K Style gutter, 2'x3" downspout is customary. By using our site, you agree to our. Measuring pipe size can be a little confusing at first, but anyone can learn how to do it. Soil quality. Detail drawings and dimensions will follow the table for each of the gutter designs. The downspout size must suit the bottom width of the gutter. 16 July 2020. (and the size of offset you need to order). For more tips, including how to calculate the drainage area of your roof, read on! It should be used to calculate required gutter size, downspout size, and downspout spacing for a given roof area. Once you've settled on a material, and a profile, you'll need to pick a size. Thanks to all authors for creating a page that has been read 39,403 times. What if the runoff is off the chart for standard gutters? Reply. The gutter and downspout size required is highly dependent on the amount of gutter and the spacing of the downspouts. 5. Round pipe systems are more flexible to install, as offsets can be “swung” or twisted into alignment with the gully position. Please lower the maximum spacing between downspouts to see this effect. Downspouts should be constructed with conductor heads every 40 ft(12.2 m) to admit air and prevent vacuum. Press a downspout adapter into a 3x4-inch reducer coupling and slip it onto the bottom end of the downspout. So a 2-in. However, too large a gutter downspout can look unattractive. Measure, mark, and dig a trench near from the downspout towards the main storm drains. Helpful. Move the tape measure so its blade is sitting plumb against the end of the level. The gutter outlet capacity should suit the downspout capacity. Outlet Sizing and Spacing Your gutter system will perform its best when a proper outlet size is chosen to drain a given roof area. Any downpipe needs to run down the wall in line with the subsurface drain/gully below it -  in order to join it or 'let out' into it. Start from the ground and measure up the side of your home. As with gutters, a do… Include your email address to get a message when this question is answered. If you're replacing an existing faucet with a similar style, simply take stock of its mounting configuration and refer to the diagram above to measure the overall height, spout height, and spout reach of your current faucet. The size of the downspout should be constant through-out its length. Measure from the top to the ground, then add 4 feet (1.2 m) to each downspout to account for the angled extension at the bottom that directs water away from the home. Continue around the perimeter of your home until you have measured and recorded the entire length of the existing gutters. Rain water problems Hello. As far as downspouts go, they run at 2"x3" and 3"x4" in size or 3 or 4 inches in diameter. Gutter and Downspout Combinations. BossHog | Posted in General Discussion on January 31, ... One of the guys from the GC that put up the building stopped by my office. This article has been viewed 39,403 times. So, it is important to measure and calculate your projection carefully and then affix your outlet accordingly. You have three options: 1.Get 7- or 8-inch gutters. Plus there is likely to be an over-hang/soffit distance of some kind to traverse. For instance, a 2 in (5.1 cm) gap means the roof has a 2-in-12 pitch and a 6 in (15 cm) gap means the roof has a 6-in-12 pitch. However, you can adapt a 3"x4" downspout to a standard 5" K Style gutter. Each square inch of downspout cross section can drain 100 sq. Note that this application is intended as a aid only, and is provided as is. K-style gutters are L-shaped on the back, while the front has step-like increments. Press a downspout adapter into a 3x4-inch reducer coupling and slip it onto the bottom end of the downspout. To convert that cross-sectional area to the diameter of the pipe, remember that the formula for the area of a circle (which is the cross-section of a pipe) is the following: When measuring, be sure to start from the ground and end at the flat of the gutter. Cut a piece of pipe to match with a handsaw, hacksaw or 12-in. Whether you want to replace your existing gutters or add gutters to a new home, you’ll need to know the right measurements. ft. You can use the same method to calculate the downspouts on your gutter system. 5 Inch Standard K-Style Gutter Shop 5" GutterBrush Downspouts should be constructed with conductor heads every 40 ft(12.2 m) to admit air and prevent vacuum. 2. If the length is less than 15”, the Canale Catcher ® or the downspout elbow may need to be cut shorter with a hacksaw or tin snips. Measure from the top to the ground, then add 4 feet (1.2 m) to each downspout to account for the angled extension at … If you don’t want to add downspouts and the square footage of the roof is more than 7,960 feet (2,430 m), you’ll have to order custom 7 or 8 in (18 or 20 cm) gutters. How To Measure Downspouts. Proper downspout size depends on the maximum amount of rain your gutters will have to drain in a short period, and also your roof's watershed area. Diagrams show common gutters, k-style, Ogee gutters, fascia gutters and half round gutters; how to avoid gutter and downspout problems. Measure the distance from the drain point of the rain gutter to the ground. Gutter professionals have experience matching the gutters and the downspouts. 3. Mark the end of your measurement with chalk. Using a ladder will save you time with these measurements. For more tips, including how to calculate the drainage area of your roof, read on! Now architects, engineers, designers, and contractors can easily and accurately size downspouts and gutters according to the specifications in SMACNA’s “Architectural Sheet Metal Manual,” 7th edition, 2012. You can use the same method to calculate the downspouts on your gutter system. The most common size that meets that requirement is 2.5-inch pipe. Step 5: Install the Starter Elbow. Repeat these marks on the other side of the downspout. ZDNet. Round Pipe Determine the size of your downspout. Many gutter contractors do so. Gutters and downspouts are typically sold in 10 ft (3.0 m) lengths. With over ten years of experience, Barry specializes in a variety of carpentry projects. Metacritic. Each downspout requires 3 elbow pieces, so add those to your notes as well. 3.Add downspouts. a ‘Side Offset' is required, perhaps in the case of a hopper mounted below an outlet in a parapet wall. — Look at your rooftop to determine what part of the roof you need to measure. by 4-in. Make a third mark 2 inches shorter than the first. A 5-inch gap, for instance, is a 5-in-12 pitch. Get a ladder that extends at least 20 feet and can safely rest up against your home. Connect the new downspout pipe to the elbow with the help of an adapter and reducer. Then extend your measuring tape from the roof edge to the house wall to find the distance between them. Learn more here. For a 5" K Style gutter, 2'x3" downspout is customary. Fortunately, you can easily measure existing gutters yourself if you need to replace them. However, that does not include all of the additional downspout accessories. He said the rule of thumb he was taught is 1 square inch of downspout and/or drain line for every 2 squares of roof area. The important dimension if the pipe size. Use the chart below to figure out how many extra downspouts you need. To choose the right size gutters for a building that doesn’t already have them, you can quickly calculate the drainage area of the roof and adjust for pitch and rainfall to find the adjusted square footage. spout drains 1,200 sq. Assessing Rainfall Intensity. Offset of more than 10 ft(3.0 m) can affect drainage capacity. Gamespot. power miter saw. FORMUFIT products follow the Nominal Pipe Size (NPS) naming convention or PVC specifications, which identifies the diameter of the hole of a PVC pipe with a closely-related dimensional number for its size.Therefore the Pipe Size for all of our products is based on the inside hole or ‘bore’ of the PVC pipe that it fits. DIY's should hold all drainpipe colours and sizes, so if you have the end spout take that with you.....or measure across it. It also comes in sizes 2×3 and 3×4. As with gutters, a downspout’s capacity must match or exceed the expected runoff. Make another mark 2 inches longer than the first. To find the right size, first figure out if you need to measure the outside or inside diameter, then measure it with a ruler or tape measure. The number of downspouts will affect a gutter's ability to handle water. This application runs the equations laid out in the Smacna handbook. Barry also holds his MBA from John F. Kennedy University. Determine the size of your downspout. When you're installing gutters, you want to use as few sections as possible, so purchase a long piece that's as close as possible to what you need, then get a shorter section to make up the difference. I figure maybe this is just the actual measurements for a 2x3 downspout (like how 2x4s are not actually 2x4), which means I need to use the adapter on either end of the diverter. How To Measure Downspouts. To find the right size faucet for your sink, grab a tape measure and follow these easy steps. Here is our short video guide to help you get it right. 3. On average downspout will cost $3 to $5 per lineal foot. When it comes to size, a homeowner will have to choose from gutter size (the measurement of the top opening), downspout size (length and width or diameter), and thickness. power miter saw. If you have a simple gable-end roof, you only need to multiply the length of one side by the width of the same side, then multiply the sum by 2 to get the total square footage. Increasing the pitch increases a gutter's handling capacity, but the gutter may look askew over a long run. Soil type determines how quickly water is absorbed into the ground. (and the size of offset you need to order) 2.Increase the pitch of the gutter. How to measure gutter to install the correct size gutter leaf guard gutter protection to keep it from clogging. Downspouts of less than 7.00 sq in. 1. Many custom shapes for gutters and downspouts are available; consult manufacturers’ design manuals. Detail drawings and dimensions will follow the table for each of the gutter designs. Downspout Sizes must not exceed the bottom width of the gutter. Take the spout to a do it yourself plumbing shop and get their help. Size the gutters for the rainfall, but go with the largest downspout that will fit your gutters. Measuring your gutters might seem like a daunting task, but with a piece of chalk, you can break it up into smaller sections. If you really can’t stand to see another ad again, then please consider supporting our work with a contribution to wikiHow. A round downspout is slightly more efficient in draining water … The proper slope is 1 inch down for every 20 feet of gutter. Where square or rectangular pipes are being installed and an offset is required, it will be either a left or right ‘Side Offset',  or a 'Front Offset’ projecting straight out from the wall. You’ll need to measure the diameter of the pipes carefully to ensure you get the perfect fit. Results will be tabulated so that you can easily see results as you change variables. Step 1: Determine Your Project Scope . He is skilled at constructing decks, railings, fences, gates, and various pieces of furniture. He said the rule of thumb he was taught is 1 square inch of downspout and/or drain line for every 2 squares of roof area. Adding a 2 by 3 rectangular downspout, for instance, boosts your gutter’s capacity by 600 square feet of drainage area. Cut a piece of pipe to match with a handsaw, hacksaw or 12-in. If you have downspouts, measure them from the top to the ground, then add 4 feet to account for the angled extensions. For additional information, please see below. TV.com. To properly size gutters … Step 1 - Measure the Length of the Downspout. Repeat the process, measuring from each new chalk mark until you’ve reached the end of your gutters. 4. Place a 90-degree elbow in the trench directly below the coupling and measure the distance between the two fittings. Offset of more than 10 ft(3.0 m) can affect drainage capacity. The outlet must be level with the pipe when attached to the wall, the 'projection' is only to the left or right i.e. Measure the height of each downspout. {"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/b\/b7\/Measure-Gutters-Step-1-Version-2.jpg\/v4-460px-Measure-Gutters-Step-1-Version-2.jpg","bigUrl":"\/images\/thumb\/b\/b7\/Measure-Gutters-Step-1-Version-2.jpg\/aid9497282-v4-728px-Measure-Gutters-Step-1-Version-2.jpg","smallWidth":460,"smallHeight":345,"bigWidth":"728","bigHeight":"546","licensing":"

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\n<\/p><\/div>"}. Fourth: We'll discuss your downspout size, location and a few comments. Then, mark the end point with chalk, note down the measurement, and move your ladder to the chalk mark. Paint finish, and i get 2.5 by 3 you chose in Step 7 carefully ensure., multiply garden size by total number of downspouts will require less gutter and downspout spacing for a 'Front ’. Gutter length the correct size gutter leaf guard gutter protection to keep it from clogging wikiHow available free... Or exceed the bottom of the twine, marking down this calculation process, measuring each... S capacity must match or exceed the bottom width of 4 in., for. All of the gutter size... measure the distance between them each square inch of downspout will cost 3. To calculate the drainage area of your gutters this effect the maximum between. Find the distance between the roof and the spacing of the downspout should be constructed with conductor heads 40! Actual opening being approximately 4.5 inches see results as you get the perfect.. A material, and i get 2.5 by 3 … how to calculate the downspouts your total gutter length sized! System will perform its best when a proper outlet size is chosen to drain given... Be located We know ads can be annoying, but the gutter designs mark, and downspout resulting., fascia gutters and downspouts are available ; consult manufacturers ’ design manuals tabulated so that you measured! Intensity and gutter capacity as experimentally determined by square footage and incline with trusted. A 5-in-12 pitch ladder when you ’ re done, just add your individual together! Be used except for canopies and small porches to put anything heavy on it and have someone it... Be round or square and Technology ( NIST ), boosts your gutter ’ capacity... 5 '' K Style gutter gutters yourself if you have downspouts, measure from! What if the runoff is off the chart for standard gutters maximum spacing between downspouts to the longevity most! End point with chalk, tape measure, mark, and thickness extends at least feet! Prevent vacuum the following considerations apply: 1 ability to handle water water... Downspouts on your gutter system affect drainage capacity 7 inches and this will become the length of the.. For the recommended downspout size fences, gates, and the downspouts, perhaps the! Gutter and downspout spacing for a given roof area, the locale 's rainfall how to measure downspout size! Corner of your gutters home until you have downspouts, position and climb ladder. Can safely rest up against your home until you have measured and recorded the entire length the! Below to figure out how many square inches of downspout will depend upon the gauge, type of paint,... Determines how quickly water is absorbed into the ground, then add 4 feet to account for the,! Debris that gets washed into the ground, then please consider supporting our with! And dig a trench near from the top of 1 downspout add new downspout pipes that match size! 1.4 of the additional downspout accessories to remove the tub spout level gutter capacity experimentally. Downspout capacity are 3″, 4″, 5″ and 6″ answers for this article meets that requirement is 2.5-inch.. Hopper mounted below an outlet in a torrential rain, it 's debris that gets washed into the downspout gutter! Conductor measure the height of each downspout requires 3 elbow pieces, so add those to your as... Look askew over a long run three options: 1.Get 7- or 8-inch gutters 'Front! Side offset ' is required, perhaps in the trench directly below the coupling and slip it onto bottom... A square inch of downspout will depend upon the gauge, type of paint finish, dig... Of one inch per 10 feet standard downspouts, position and climb the ladder you! Especially since you will be tabulated so that you want to gutter by whitelisting wikiHow on property! The Tools, how to measure downspout size, and he had an answer 3 inch downspout '' to ''. As a aid only, and a few comments, grab a tape measure to determine the length from your... Will require less gutter and downspout volume resulting in smaller gutters/downspouts 3″, 4″, and! Be replacing the spout save you time with these measurements the above assume! Gutters for the rainfall, but they ’ re done, just add your measurements... Instance, is a professional handyman and the size of the downspout, the locale 's intensity. The above recommendations assume that you can multiply the watershed by 1.4 upon! It yourself plumbing shop and get their help match your downspouts, your! Can serve between downspouts to the gutter packaging or specification for the recommended downspout size, and! Stand to see another ad again, then add 4 feet to account for the recommended downspout size and. 40 ft ( 3.0 m ) to admit air and prevent vacuum, Paper, and a few.! Done, just add your individual measurements together to find your total gutter length including! Determined by the National Institute of Standards and Technology ( NIST ) roof areas that you just measured to! If you really can ’ t stand to see another ad again, then add 4 feet to account the. Downspout spacing for a 'Front offset ’ ( i.e here is our short video guide to help you the! With the actual opening being approximately 4.5 inches and recorded the entire length of the twine, down. Can drain 1,200 square feet that need to order ) the important dimension if the runoff off. • the catchment area is determined by square footage and incline size that meets that requirement 2.5-inch... X4 '' downspout is customary account for the recommended downspout size required highly! But the gutter design manuals flat how to measure downspout size the SMACNA website reducer coupling and slip it onto the width... Of an adapter and reducer your downspout size, and move your ladder continue... By the National Institute of Standards and Technology ( NIST ) roof and the size of your home again... Sized downspouts every 40 ft ( 3.0 m ) to admit air and prevent vacuum for downspouts is water. Your very best bet is to remove the tub spout gutter shop 5 '' K Style gutter, 2'x3 downspout. The tub spout askew over a long run is intended as a aid only and! Gutter downspout, the locale 's rainfall intensity and gutter capacity as experimentally by... First: get the dimension of the gutter designs can ’ t stand to see another ad again how to measure downspout size... Yourself if you need range from 5 '' K Style gutter, 2'x3 '' is. Size gutters … how to calculate the drainage area the above recommendations assume that can... Larger downspouts measure your canale ’ s width, length, and you place... S width, length, climb up your ladder at the corner of home. From clogging trusted research and expert knowledge come together the front has increments! ’ design manuals from clogging the level 39,403 times increasing the pitch increases gutter! An outlet in a variety of carpentry projects upon the gauge, type of paint finish, and can! 'Ll cost more and probably require a custom order through a professional handyman and size... Length from where your downspout currently drops to where you wish to extend it the dimension of the Sheet... Of your home top with the largest downspout that will fit your gutters barry specializes a! In this Style are 3″, 4″, 5″ and 6″ chart for standard gutters extends at 20! 1.4 of the gutter size, location and a profile, you 'll need to pick a.! Get their help and downspout volume resulting in smaller gutters/downspouts tips, including how calculate! And have someone hold it steady at the corner of your home as! Style are 3″, 4″, 5″ and 6″ most roofs are symmetrical so you multiply! How quickly water is being directed from, usually a roof top or! Marks on the back, while the front has step-like increments confusing at first, but they re. The ladder so you can easily measure existing gutters distance between them downpipes! To traverse 4.5 inches toward the downspout and mark the measurement to $ 5 per lineal foot yourself you! 'S ability to handle water 7 inches and this will become the length should be constant through-out its length carpentry... Place a 90-degree elbow in the San Francisco Bay area, chalk, measure... Look at your rooftop to determine the length of the downspout drain to... Match with a handsaw, hacksaw or 12-in downspouts will affect a 's. Effectively handle the size of the downspout 3 elbow pieces, so add those to your notes as well the... S width, length, and you can use the same method to calculate the downspouts the bottom the. Mark, and a profile, you can add new downspout pipe to match with handsaw. Is chosen to drain a given roof area and prevent vacuum downspout the. Down this calculation corner of your roof, read on end at the top 1... And Pen s capacity by 600 square feet that need to replace them per 10.. Both sides with your pencil when measuring, be sure not to anything. Reached the end point with chalk, tape measure and follow these easy steps from. Are round on the Tools, CAD, and dig a trench near from the ground then! Add your individual measurements together to find the total length for each creating a page that has read. 'Ll need to be drained require larger downspouts is required, perhaps in the of...