The vertical drop for every meter of horizontal distance is a crucial parameter for rainwater drainage design. It could be much lower than the height to which water could back up in case of clogging or overtopping by debris for example. Otherwise, the system would not drain properly under any circumstances.
What is a Gutter?
A gutter is a channel on the roof of the house. The water flows along with it and is collected under the eaves in a larger pipe (eavestrough) outside, where it can flow to the ground or be diverted onto another surface of the land. To ensure that rainwater from a roof does not accumulate next to a wall, courses are set at the edge of the roof. That makes better opportunities for drainage and contaminates can work themselves out before they flow further into the ground.
Types of Gutters
A gutter can be made of many different types of materials, made of aluminium, steel or copper. The materials usually differ in price between each other. In addition, it is also about the type of guttering. The most common and well-known form is a classic gutter along your roofline. Most modern houses have so-called K-gutters which are a piece divided by a roof beam.
The composition gutter is made from steel, copper or lead. It is more expensive than an aluminium gutter but will last longer and give a nice look. The materials are subject to corrosion, so the gutters must be maintained regularly.
Box gutters consist of a series of boxes with spouts in which rainwater has room to accumulate before it flows away. The box gutters are not suitable for homes with an overhang and therefore can be installed on the lower part. The box is made of plastic or metal. The composition gutters are often used for decoration purposes on facades.
The construction gutter is made of strong material, which goes around the house on waterproof high-density polyethylene(HDPE). The gutter is incredibly strong and does not rust, but it is much more expensive than aluminium or composition gutters.
Gutters for Flat Roofs
It may seem unnecessary to have a separate gutter on a flat roof since rainwater flows off directly in the direction of the fall. However, this drainage works only if the roof tiles are properly sealed. If this is not the case, rainwater can penetrate your roof and damage it. With a separate gutter, one has to consider that the angle of the fall is about 45 degrees until you drain into an eavestrough.
What is a Roof Catchment Area?
The catchment area is the area of your roof on which water can fall. The larger the catchment, the more rainwater you collect. For houses with a small roof catchment area, installing more guttering systems works best to prevent overflow and damage to eaves, fascia and similar.
The length of the gutter per meter varies between 100 cm and 150 cm. The size also depends on how many objects are drained by the rainwater system. For example, if you have many trees on your property or buildings which you want to drain as well as your roof, you need more catchment than if you have only a few trees and only one roof.
How Often Should I Clean My Gutters?
It depends on how dirty the guttering is and how many problems you want to avoid. At a minimum, clean them if they are full of leaves and other organic matter because this can clog up the smaller channels in the gutters causing a damming effect, so water can overflow from them or silt up at their bottom.
How Often Should I Check My Gutter?
You have to check your guttering regularly for blockages. A minimum of at least once a week. Blockage can cause flooding because the water cannot be drained properly anymore.
What is the Australian Code AS/NZS 3500.3?
The Australian code AS/NZS 3500.3 is a standard for the drainage of buildings and their annexes, drain systems and secondary drainage. NZS 3500.3 covers the construction of the building drain and secondary drainage, including on-site storage, such as ponds.
NZS 3500.3 Codes for Gutters and Guttering
1. You must have a gutter around the entire perimeter of the building.
2. Ensure all water from your roof is drained to either an internal or external drainage system.
3. Ensure downpipes and boundary edging are free of obstruction.
4. Make sure that water is diverted away from the walls.
5. Ensure that water flows freely down your gutter and does not overflow.
6. Ensure you have an adequate storage capacity.
Gutter Maximum Fall Distance?
No definitive calculation for a certain fall is possible due to numerous variables that affect it. The key factors are generally rainfall intensity, gutter make-up and building geometry/slope. In general, the faster the rain falls from heavy clouds, the more quickly it collects in the culvert. If the rain falls from a thin layer of clouds, the rainwater will drain more slowly to prevent flooding.
In Australia, balconies must have gutters if they are higher than 3 meters from the ground or there is a risk that water can flow down in an uncontrolled way.
It is necessary to ensure that rainwater from a roof does not accumulate next to a wall, so courses are set at the edge of the roof. These should be no more than 600mm apart and 600mm below the top of the wall. The code also states that gutters must be pitched so water will drain down towards ground level and the ends of gutters must not be higher than 900mm from the ground.
What Fall Should a Gutter Has?
It is generally accepted that gutters should have a fall of 1 in 200 (1-metre run = 200mm fall). If the roof has a pitch lower than 20 degrees, an alternative formula can be used to calculate fall. This provides for the calculation of the rise over run between 2400 and 600.
Management of Water
1. Never let the rainwater sit in the gutter for any length of time, this allows organic debris to hold water and create mosquito breeding habitats. Direct downpipes away from your home or property.
2. Ensure that all downpipes are free-flowing and terminate at least 1 metre from your home’s foundation, to prevent overflow. If you have a French drain, ensure that it flows at least 30 cm below ground level.
3. Keep the grass around your home mowed to allow water to penetrate into the soil more easily.
4. Check your downpipes regularly for blockages and remove any debris that has collected in them to prevent damage or overflowing.
5. Check that gutters are draining properly and water is flowing freely through them.
6. If your drains become blocked or there is excessive pooling near your home’s foundation, contact an expert (e.g., plumber) to investigate the cause of the build-up and resolve it as soon as possible to prevent damage to your property.
7. Properly maintain your downpipes and guttering to prevent mosquitoes from breeding in them.
8. A well-maintained guttering system keeps the property safe and within building code.
9. Check for water pooling near the foundation of your home or accumulation in sump pits, unblocking drains if necessary and/or install a sump pump.
10. If you install a rain barrel or box, ensure the overflow is directed away from your home’s foundation and any nearby windows or doors.
How do I Identify an Incorrect Fall?
If your gutter slopes away from the house, make sure rain does not pool by using a broom or leaf blower. If your gutters are overflowing, this is an indication of clogged leaves and debris that require frequent cleaning to prevent damage.
How do I Identify a Correct Fall?
If the slope of your gutters towards the building, make sure rain is draining well away from the building foundation to prevent water damage. This could be done by pouring a small amount of water into the gutter at ground level, if it then drains away quickly that indicates that you have enough fall in your gutters.
How do I Solve an Incorrect Fall?
If the fall is too steep, first inspect the downspout for blockages or debris that may be hindering water flow. Consider installing another downspout if necessary to direct more of the roof drainage away from your home’s foundation. If you can’t find anything wrong with your guttering system, contact a professional who can make changes to ensure water flows away from the home, doesn’t overflow and causes problems.
Roof Drainage Systems
Roof drainage systems should contain at least two downspouts to direct water away from the home. One downspout should be placed near your downspout. This serves as a backup in case the other fails or is blocked. This drain should be installed much higher than the height of your garden to prevent water overflow pooling in your garden when it rains.
A guttering system that regularly overflows or is clogged with vegetation will cause damage to your roof shingles, eaves, fascia boards and other components. Water leaks inside the home can lead to mould, rot, peeling paint and weakened floors. You’d have to replace a lot of stuff.
The most important responsibility of a home owner is to protect the foundation of their homes from water seepage. Improper Installation of a guttering system means that if the gutters are not installed correctly then there is no protection for your roof, walls or foundation area when it rains. You will need professional help and maintenance to get the job done.