Properly Installed Roof Drainage – Gutters And Downspouts

The volume of rain that befalls a house even in a drizzle is so astounding that most homeowners will be shocked to find out.

If there is no proper drainage system on the roof, every time it rains, water will curtain the perimeter of the house like one of those waterfall features in classy hotel lobbies.

And if water is allowed to soak up particular areas of the house, it can cause serious problems to the foundation and the house itself.

And while a pitched roof will be more efficient in shedding water due to it’s intentional slopes, flat rooftops can be a tricky affair to build when roof drainage is concerned.

This is why gutters and downspouts are essential to collect, channel, and direct rainwater away.

They must be adequately sized and maintenance must be done bi-annually to remove debris like leaves and twigs. This is even when you have screening installed.

From a seasonal perspective, you’d find the most dead leaves on the roof in spring after trees have bloomed, and fall after leaves have fallen. So you might want to plan the maintenance accordingly.


If you walk into a proper architectural firm, you’d find that they have various charts showing the “correct” gutter sizes based on various factors like rainfall and square area.

The average house will usually have one of four to five inches in width.

This is available in 2 main profiles. The unmistakable half-round and fascia (K-style).

Yet the size and shape is not all there is to it.

Yes, a bigger sized gutter will understandably have a higher capacity to transport water. But there are other important characteristics to inspect.


4 materials are most common for gutter fabrication:

  1. Aluminum
  2. Galvanized steel
  3. PVC (plastic)
  4. Copper

Aluminum is one of the wonders of science. It is resistant to corrosion, durable, affordable, easily cut on-the-spot, and used in many of the household appliances we find at home.

So it is no surprise that it is the most popular material used for gutters in new constructions.

Galvanized steel on the other hand is tougher, more sturdy, and less vulnerable to dents and damage compared to aluminum.

The issue with it however, is always about how quickly it can rust when the paint finish peels off. So they need to be painted every 3 to 5 years.

FYI, magnets will stick to galvanized iron.

PVC is very economical and actually does the job of water marshal very well. But it is very prone to damage especially in winter. Just strike one firmly with your elbow and it might break if you are unlucky.

It’s expansion and contraction can also often lead to seam problems. This look and feel of fragility turns a lot of homeowners off.

Copper can be very pleasing to the eye and has about the same features as aluminum. They can last the lifetime of the house and are considered top of the line.

But oxidization changes it’s color. The biggest snag however, is it’s steep price.


If there is no support to gutters, it would sag and collapse when the water load becomes too much to bear.

Imagine an overhead highway without structural support pillars below and you get the idea.

This is why they must be supported by support straps (hangers) about every 30-inch section. If the house is located in an area known for heavy snow, then reducing that 30-inch space is recommended.

Meaning you have to install more straps or spikes in closer distance.

When fixing up the support, be mindful to enable a slight slope of about an inch for every dozen feet. Ending with an outlet into the downspout.

Crooked alignment can cause water to back up resulting in damage to wood eaves and the roof itself. They need to be reset.

If appropriate sloping is setup, water shooting out at the end of a gutter is likely due to a missing end cap.


When leaks and drips on gutters come to the attention of homeowners, they often attribute that to negligible cracks or small holes.

But a lot of times, that is not the case.

Leaks behind gutters or water stains are symptoms of clogged gutters or downspouts.

When it comes to assessing clogs, it’s not about how bad the clog. It’s about how long the clog has been doing it’s naughty stuff.

Clearing the clog is a simple enough task to undertake. But if the cog has existed for some time, it could accelerate or induce corrosion. It can also cause mold to grow.

A common cause of leaking activity is the the absence or a defective drip edge. This can be the root cause of leaks and stains behind gutters.

On much steeper roofs, water will be running down at a much faster pace. This increased velocity will mean a tendency for water to overshoot the bottom of the roof valley. There must be a presence of splash guards to manage this.

Only after ensuring that there are no other problems causing leaks, should you consider the possibility of an undersized gutter.

As galvanized steel is vulnerable to rust as mentioned earlier, it is a cardinal rule to survey for stains and leaks. This is because they are more serious consequences compared to say PVC.

There is a very high likelihood of the gutter rusting through when this happens.

You might be able to retain control over the problem in the short term by patching up affected areas with mastic. But over the long term, it inevitably has to be replace.

Please do it before the condition gets much worse. That can lead to water damage to the house. Costing you way more than just a gutter replacement.

Collapse sections

Gutters are installed firmly and sturdily… unless the contractor did not do it right the first time.

Let’s just assume it was done properly when initially installed.

Sections that collapse are not normal. They should be strong enough to weather any normal circumstances.

So these are usually caused by falling branches or from third party intervention like fat cats playing on the roof.

They should be fixed before the whole structure collapse. Someone might get hurt.

At the same time, loose gutters and sections must have come loose over time or from bad workmanship. This can usually be easily fixed by fastening hangers or replacing them.

Wood gutters

While not a logical choice by homeowners, often times it’s not their fault.

Maybe it came stock and built-in when the house was purchased by a builder. They are seldom used on modern residential property these days.

They are usually made of Douglas fir or red cedar and coated with an asphalt-type paint.

Look out for stains and damage on the interior surface and joints at the end sections. If the gutter is dry, check for rot and cracking.

It is best to replace them. But if that is not possible or simple not cost-effective, then cover damaged areas with waterproof flashing tape.


The downspout should be in the same size as the gutter. And ideally the same material as the gutter.

It should discharge water promptly at least 6 feet away from a house, and preferably not on an inward slop on the ground that can direct water back into the house.

The ideal scenario is for rainwater and melted snow to discharge onto drainpipes or sewer carrying water to a safe location away from the house.

Some households discharge on the lawn surface. If that is the scenario, then a splash block should be used to prevent erosion of topsoil.

Inverted installation

You cannot help but chuckle a little when you discover this. But there really are roofers that make the cardinal mistake of installing a downspout upside down…

… making it an upspout!

Jokes aside. This can cause leaky joints on the fixture.

A key giveaway of inverted downspouts is when you observe upper sections overlapping lower sections.

It needs to be reversed.

Stained wall siding

In theory, stains on exterior wall siding should not occur under normal circumstances. So when this happens, it could be caused by corroded or split seams that allow water to seep through.

Or it’s because of the upsprout.

Soggy soil

If you find soggy or sunken ground around the house, especially near the water discharge, it is a sign that the discharge is not far enough away from the house.

Occasionally, it can also be the root cause of wet basement problems.

If you find that the discharge point is already more that adequately distanced, then it is possible that the drains are clogged or damaged.

In this case, you need to call and hire a licensed plumber for help.

Finally, remember that a quality roof is only as good as the roof drainage. Without a proper system installed to remove water shed by the roof, a house will still suffer from moisture attacks.