Under Deck Drainage System: Definitive Guide | deckinformer.com (2024)

Consider installing a DIY under-deck drainage system if your deck is elevated, particularly if it’s a second-story deck. Water cannot flow through the floor and collect below as a result.

Instead, the precipitation drains into gutters, keeping the space underneath the deck dry and functional.

Under Deck drainage systems protect your deck frame from moisture that can cause wood rot and decay while creating a dry, usable area underneath your second-story deck.

Water from the deck is diverted by an under-deck drainage system, extending the lifespan of the building by avoiding rot, mildew, and other structural problems.

Types of Drainage Systems

Deck drainage systems can be broadly divided into two categories: those that place above or below the deck joists.

Even though the initial construction is the ideal time to implement deck drainage, you can still waterproof a current deck by using a drainage system.

Underdeck drainage systems can collect and reroute water in one of the three areas of the deck on the deck’s surface, within the decking and the beams, or below the joists.

Some deck drainage systems inserted into the gaps between the decking prevent water from getting below the deck, forcing it to flow off the outside deck or into a gutter that runs along the edge instead.

Regardless of the best deck drainage system for your deck, you will gain more dry outdoor living areas underneath your deck that you can use for many years.

If you’re adding a new deck to your house, get the most out of your expenditure by installing an under-deck drainage system. Following installation, you can use the area below the deck for a waterproof under-deck system.

Also Read: Aluminum Under Deck Ceiling: Why Choose It?

Reasons for Installing Under Deck Drainage System

There are several reasons to build an under-deck drainage system. It takes a deck-drainage system to keep the deck looking the same for years. It has several reasons, including the following.

• It lessens the possibility of algae and moss development due to damp wood, preventing the deck timber from rotting due to moisture.
• It stops the deck from becoming submerged in water during prolonged downpours.
• You can use the area beneath the deck for any practical purpose and keep it dry even in the rain with an effective under-deck drainage system.
• Your deck’s drainage system keeps waterproofing for secure gas and electric fittings. You can purchase a deck drainage kit and set it up at home, making it inexpensive and simple.

Benefits of Building An Under Deck Drainage System

Builders of second-story decks should consider adding an under-deck drainage system to their budget. The homeowner’s outdoor living space is doubled, which is the primary advantage.

Setting up an under-deck drainage system allows builders to increase project profits, which is another advantage.

When a two-story deck is equipped with an under-deck drainage system, there are many more advantages for both residents and builders. The top four are as follows:

Construct a dry Outdoor Living Area

Water can be drained from a deck using an under-deck drainage device.

Some under-deck drainage systems channel water into a gutter system that transports it from the deck using a network of troughs and drains.

Doing this creates a dry, weather-free space beneath the deck. It doubles the number of outdoor living areas that homeowners have.

After implementing the system, homeowners can add amenities for ceiling fans, lighting, entertainment area, and more.

After that, they can add the ceiling or soffit to complete the room. You can store things in the dry area under the deck.

Also Read: Waterproofing Under The Deck: The Most Effective Solutions

Keep Moisture Away from the Deck Substructure

Different under-deck drainage techniques exist. The timber is kept safe by mechanisms that use a polyurethane or rubbery membrane that hangs over the joists.

This system offers complete water security for all the supports and joists.

It stops the rot and degeneration of wood that usually occur at around 8–10 years from affecting the joist substructure.

It is worth purchasing to ensure the deck foundation lasts the same duration as the deck it supports because the typical deck is warranted to last 25 years.

Dry Outdoor Area

Homeowners believe an under-deck drainage system is worthwhile even though building a deck costs a little more.

The homeowner quickly understands the value of having a dry outdoor living area to enjoy inclement weather after the first rain. There’s no reason to let the rain ruin a celebration.

Without worrying about getting wet, the visitors can still appreciate being outside.

Increase Your Profit

A builder can increase profits on a new deck job without adding more staff by installing an under-deck drainage system.

A builder could make a few thousand dollars more by including an under-deck drainage system and a roof in the job, assuming a 20% profit margin on a 325-square-foot deck.

A greater profit could significantly boost a company’s bottom line over the year. Installing an under-deck drainage system is advantageous to both architects and homeowners.

Homeowners double the size of their outdoor living area, and builders acquire pleased clients and some extra dollars. Both the householder and the contractor benefit.

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Installation Procedure of Under Deck Drainage System

Installing a drainage system during construction is the best way to waterproof your entire deck. A deck drainage system diverts water from the joists and timbers.

A deck drainage system installed over the joists offers complete protection from the harm frequently getting wet wood can cause.

It can be fitted with a wooden or composite deck and covers and protects the entire wooden substructure.

Use troughs that run within joists and drain into the system’s downspouts to implement the area beneath your deck by following these construction fundamentals.

• You’ll need to adjust the pipes and downspouts to suit the space if your deck has odd angles, oddly distributed joists, fence posts inside the framing, or other special instances, but the general strategy is the same
• To ensure that water drains to the gutter, install the pipes and downspouts, and then fully tape over all joints with butyl tape.
• The downspouts resemble funnels, slide between joists positioned 16 inches apart and, when rotated 90 degrees, 12 inches apart. You can also modify them to suit joists with unusual spacing.

• The downspouts’ 10-inch height makes them a match for 2×10 joists. Cut the funnel outlets to 1 inch into the gutter if the joists are smaller. Use self-drilling screws to attach a piece of PVC downspout to the funnel outflow if your joists are 2×12 in size. Next, using a utility knife, cut a crescent-shaped piece from the bottom of the funnel. Adhere to the cutline. To position the gutter, place a downspout inside every joist bay at the edge of the joist and secure it with staples.
• Open a drain panel and give it time to adjust. (relax). Then, make a crease by folding it in half longitudinally. It will aid in creating a channel for the water to flow through. As far as you can, tuck one end of the cloth beneath the ledger flashing and secure it with a staple. Avoid stapling the lights.
• To ensure that one border of the trough panel is flush with the edge of a joist, staple that edge over the top of the joist. As you staple the trough, keep it tight. (Have an assistant hold the other side of the trough at the ledger end to make the job easier.) Fold the substance back firmly once you reach the downspout to eliminate its roll memory. Then, trim it so the end is close to the downspout hole’s middle.
• Continue stapling the trough’s two edges to the instructions on the panel. As a result, there will be a small slope for the water to flow down. In the remaining joist spaces, keep putting in the trough panels. To ensure each trough empties effectively, pour one cup of warm water.
• If angles or cantilevered deck sections cannot support a downspout, create short trough portions and back-pitch them so that water runs to the extended trough and into the opening in the downspout. It’s acceptable to use butyl sealant rather than, or in conjunction with, tape in challenging areas.
• Remove any extra overhanging trough material with a utility knife or pair of scissors without exposing the bare timber. Put the butyl tape to the stapled trough ends, detaching the paper covering. Start at the house end and make your way toward the downspouts. Work slowly to prevent the tape from curling, and apply pressure firmly, so it creates a tight seal. Work slowly to prevent wrinkling of the tape and apply pressure firmly so that it forms a strong connection at all places.
• Next, wrap the tape around the downspouts’ outer border. To maintain the seal flat:

1. Cut the tape as necessary.
2. Press each component firmly and smoothly.
3. Apply more tape to a joint if you aren’t positive it is properly sealed.

• You can now put in a fan or other overhead fixtures if you want to. All areas below the deck remain dry because this system drains water from beneath the deck.
• Construct a gutter out of PVC, aluminum, or steel to sit beneath the downspouts. Each exit extends one inch into the gutter. The gutter should have a small slope, typically 1/8 inch per foot, so that water drains toward the downspout.
• You can use hidden fasteners or face screws to attach the decking. The fasteners pierce the tape, creating an impenetrable around them. The deck planks should be kept from being fastened with nails.

How to Waterproof the Deck You are Building?

You can waterproof your deck through methods such as an under-deck ceiling system, and floor flanges, etc. You must implement suitable drainage if you want the exterior wood deck to last longer.

Your outdoor living area may deteriorate and lose its luster over time because of exposure to water, heat, and harsh weather conditions.

Please continue to discover the best option for keeping your deck strong and dry for many years.

Floor Flanges

The gaps between the deck boards act as a handy drainage system for precipitation to prevent extended moisture exposure. Rainwater is diverted to the space below the platform.

If you want the area below to be dry, then rubber flanges can be used to plug these gaps as one waterproofing option. These stop water from falling and can function as gutters to direct water to the deck’s borders.

The deck planks may need to be trimmed around some flanges to make room for their shape. Incorrect installation could also cause them to degrade over time, making the waterproofing system useless.

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Under-Deck Ceiling Systems

The method for under-deck ceilings is an additional remedy. Ceiling Systems are placed beneath the deck boards like the flanges; drain the water, acting as a drainage system and a polished ceiling.

With corrugated plastic or metal panels, they collect and discharge water away from the boards.

However, this method permits water to run via the planks and over the wood joists because the draining occurs beneath the decking materials. As a result, these decking joists will ultimately begin to rot if they are frequently wet.

Below-The-Joist Deck Drainage System:

Installing metal or durable vinyl sections beneath the joists creates a below-joist under-deck drainage system.

They construct a sloped surface to channel water into a drain conduit fastened to the peak of the platform beam, which then transports the water to the primary drainage system.

It is simpler and less costly. Water will fall through the wooden boards throughout the joists and collect in the sewage system unless a deck drainage system is installed underneath the joists.

Below-deck joint drainage is a great repair technique because it doesn’t require disassembling the deck.

The below-the-joist deck drainage method does have a few other drawbacks, though. Below-joist drainage networks bring on wood rot in three different ways:

• Rainwater flows through the roof and into the drainage system below, continuously exposing the timber to the water and weakening the structure. The wooden joists get wet after the water strikes the bottom and runs out.
• This kind of device can also trap moisture. No air enters to dry the wood if the ceiling panels are set up underneath the deck. Between the quarter-inch or smaller space between boards is where there is any proper ventilation.
• The trapped, waterlogged timber is further cooked by the hot summer weather, which also hastens the rotting process. It will cause the wood of your porch to rot over time.

Over-The-Joist Deck Drainage System

Choosing an over-the-joist system will prevent moisture from ever penetrating the joists and timbers because the drainage lines will be positioned above the joists.

An over joist drainage system is a system of drains made of waterproof material, such as latex, PVC, or rubber, draped over the joists and the wooden boards.

Drainage lines collect any water that seeps through the spaces between deck planks and guides it to the deck’s exterior edge, where it flows into a gutter that leads to the primary drainage line.

The finest deck drainage system is installed above the joists to shield all columns and joists from condensation caused by water dripping.

Because the the joist system separates the galvanized metal from the wood, fasteners stay in position longer.

However, installing an over joist under the deck drainage device is difficult. As a result, it is a superior choice for new deck construction.

When adding an over-joist system to an existing deck, all flooring must be removed and replaced after the drainage network is fully set up.

Therefore, choose an over-the-joist option if you’re building a new deck. It will help the foundation of your deck last very long.

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Add the Protection of Wall Flash

During the building process, you have the opportunity to extend the lifespan of your deck. Take into account any wood that has been exposed to the weather.

Installable and self-adhesive Wall Flash creates a waterproof seal between your home and the ledger board. Wall flash sealant is a small investment that yields significant returns and is best used when building new decks.

Considerations Before Installing an Under-Deck Drainage

It is possible to place gutter and drainage systems above or below the joists for decks. Joists and fasteners are shielded from water damage by above-the-joist devices, preventing rot and corrosion.

Below-the-joist panel under-deck gutter systems cannot provide such protection because water will always come in touch with the joists.

In reality, the panels can quicken decay by holding wetness in the joist bays. Rotted wood may even collapse onto the panels, obstructing water flow and aggravating the issue.

It’s also challenging, if possible, to place fans, lights, or other electrical components in the ceiling beneath the deck using any below-joist method, be it a retail package or a do-it-yourself under-deck drainage system.

How Much Do Under Deck Drainage Systems Cost?

The least expensive choice is corrugated panels, which cost about $1 per square foot or about $300 for a deck of average size.

Brand name units are considerably more expensive; they cost as much as $9 per square foot and start at $4. The cost of deck drainage systems can differ greatly.

An above-joist system is implemented when a fresh or new deck is being constructed and is typically less costly than the under-joist system that creates a finished ceiling.

But bear in mind that the expense of a finished ceiling is not included in the joist systems mentioned above.

Be sure to account for the price of adding a finished ceiling after the drainage system and a new deck are installed, as these systems use unsightly plastic and rubber.

Is an Under Deck Drainage System Worth the installation?

Yes an under-deck drainage system is worth the installation.

You now have additional space to store items and/or enjoy the outdoors thanks to an under-deck drainage system that maintains the area under your deck dry. Additionally, it increases the value of your house.

The method lengthens the useful life of the deck by shielding the supporting joists from moisture. Few home enhancements can offer such a significant return on such a small expenditure.

How Can Water Be Redirected Under a Deck?

Water can be redirected by Installing a drainage system beneath the as the joists are installed over a high-quality under-deck drainage system, preventing water from coming into touch with the wood supporting your deck.

This is a better method to remove water and safeguard the wood of your deck.

Membranes in an over-joist system collect water that seeps through the decking planks. Water is diverted far from the house by accumulating on coverings that drop into downspouts gutters at the border of the deck.

This method will keep the fasteners, screw in place for a longer period, and completely protect all the beam and joist from water penetration.

You can create dry room under your upper deck for a variety of outdoor living and storage possibilities with a waterproof deck system.

This outdoor living area can be used for relaxing, eating, and entertaining. You can add a ceiling, soffit illumination, ceiling fans, and much more with a waterproofing drainage system!

How Durable Is Under Deck Drainage System?

The joist substructure under the deck is very durable as it can avoid mildew, rot, and timber decay by using a membrane-based drainage system, which usually lasts for 8 to 10 years.

It is worth making the purchase to make sure the deck foundation lasts for the same time as the decking it supports because the average deck design is guaranteed to last 25 years.

Conclusion

Drainage systems for under decks have grown to be a very common improvement.

By capturing water and directing it to a drain at the deck beam or the outermost joist, these products keep the area beneath the deck dry and open for use as outdoor living space or storage.

A well-designed deck drainage system keeps the area below the deck dry by preventing rain from seeping through the deck’s above-deck gaps.

Under-deck drainage systems can be retrofitted to an existing deck as well as above-joint systems that are placed as the deck is being constructed.

In addition to keeping water from entering the area below, above-joist systems also shield the deck’s framing from moisture, prolonging the deck’s lifespan.

Under-joist devices produce a finished ceiling, improving the appearance and feel of the underdeck area.

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