National Building Inspectors - How to Build a Waterproof Deck

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Each publication, you will find helpful comments and pictures to help build your knowledge base. This information is not to make you a home or termite inspector. It’s to increase your core knowledge to make you even more valuable to your client.

Replace your old wood deck with a beautiful new deck

Several years ago, I purchased a beautiful house with an UGLY wood deck. I "hated" it.

In the spring, it would be covered with mold and mildew. In the summer (when it dried out), it would squeak so loud you couldn't hold a conversation.

I couldn't replace it fast enough. After nearly a year of research, I decided to create my own solution. I considered the composite decking, the sheet vinyl; concrete capped decking plus many other options. Not liking any of them, I decided I would create a waterproofed deck of my own design.

Check out the difference! ! !

I installed a natural slate stone for the deck surface with a glass railing system. Because the deck was 1300 sq. ft., I wanted a way to cut down on the cost; so I decided to perform all of the labor myself and make this my summer project

Reconstruction of a traditional wood deck falls within several major categories.

Demolition:

A waterproof deck needs to be sloped away from the house to discharge all of the rain water. This will require demolition of the complete deck surface starting with the deck railing.

I started with the railing system. At first, I tried to delicately pull each nail and unscrew each screw on the balusters. After the first 20, I realized it was time for the sledgehammer. (It went a lot faster after that. ha! )

Because I had to create a sloping deck, I needed to completely redesign the steps.

Building the substrate:

My beautiful wife (and best friend) helped remove thousands of screws from the deck boards.

The very BEST time to install a new waterproofed deck is when your old deck needs to be replaced or repaired.

After inspecting and replacing any damaged floor joists, I added new floor joists right along side the old ones. Notice that I didn't have to use pressure treated material because this deck was going to be waterproofed. This saved a LOT of money.

Notice that I've sloped the new joists at 1/4" per foot. This would allow the water to freely flow away from the house. (This slope is nearly imperceptible on the completed deck.)

Also notice that I replaced the deck surface in stages so I had something to walk on.

Only the skeleton of the original deck will remain.

Adding the additional joists really strengthened the deck. Now I have the equivalent of 4x8" joists every 16". After the joists, I installed 3/4" exterior grade tongue & groove plywood as my substrate. NOTE: All work performed up to this point would be required for any type of water proof deck. From this point, you could install the sheet vinyl, a concrete cap, or the slate tile as I chose to do.

Waterproofing:

Waterproofing obviously is the MOST IMPORTANT aspect of constructing a waterproof deck. It is imperative that you do everything possible to seal every potential point of entry. This IS NOT the area to rush or skimp on.

My house is sided with Hardiboard (concrete) siding. I removed the bottom 1-2 boards to insure that I could flash the deck-to-house connection.

I first filled all voids between the house/deck with thinset mortar. (This was my first layer of protection.)

Then I coated the thinset with a rubberized product called RedGard. It paints on like a thick paint.

RedGard will dry a bright red within 15-20 minutes. Once dried, I installed 2" "L" flashing by running a bead of silicone sealant on the bottom side. (Again....don't skimp on costs. I use Polyseamseal sealant which is about twice as expensive ($4.00 per tube) as DAP. I have found that DAP will shrink and split at the seams. This is NOT what you want to have happen to your new deck.)

"Think like water".....If you were water, how could you enter the house? At the base of each step, I installed the metal flashing. Then I installed tar-paper over the flashing. On top of the tar paper, I installed another set of flashing. Flashing should be like fish scales....where water will run off one onto the other, etc.

I coated over the top of the flashing with even more RedGard for added protection. In my opinion there is no such thing as "over kill" when waterproofing.

Installing the tile substrate:

Flexing in the framing or expansion and contraction of materials (due to temperature changes) will cause ceramic tile or natural slate to crack. Installing double floor joists made my framing stiffer than what is inside of my home. Now I had to deal with the expansion and contraction.

I installed 3'x5' sheets of 1/2" thick Hardi-backer over "flexible thinset". This is a mortar mix that is heavily impregnated with rubberized latex. This allows the wood and Hardi-backer to expand and contract without transmitting the movement up through the tile.

I sealed all of the joints with fiberglass joint tape and more thinset. Then, I coated the Hardi-backer with more RedGard.

RedGard is quite pricey at $30 per gallon but it is a great product. It creates a seamless thick rubberized membrane over then entire structure using a paint brush and roller. (I applied two coats for added protection.)

Besides providing a water proof membrane, RedGard offers another layer of flexibility....further preventing the tile from cracking.

FINALLY, I'm ready for the "pretty stuff". Wanting to add a more dramatic element, I decided to lay the tile at a 45% angle. (NOTE: I was able to get my tile from a tile distributor for only $2.50 per sq. ft which was 30% less than what I was quoted by Home Depot.)

YAHOO!! The tiling is done. You will notice that I've completely redisigned the staircase. For greater appeal, I added recessed lighting on the edge of the steps. Now I need to grout the tile and re-install the siding.

YUK! ! Grouting is probably the worst part of the entire job. I could only grout 30-40 tile at time before having to start washing it down. I would wash, rinse, wash, rinse for a total of five (5) times on each tile. I wanted to make sure that I removed all of the grout from the slate surfaces so I could maintain the natural beauty of the tile.

Here is the finished deck...waiting for the glass railing system. I'm very pleased with how it came out. It's rich looking, waterproof and very easy to clean. Everything that I required in my new deck.

In addition to the self pride of building the deck myself, I'm very pleased with the money I saved. The tile, hardi-backer, thinset and RedGard cost me only $4.50 per sq. ft. The additional floor joists and plywood decking cost me another $3.80 per sq. ft.

Depending upon your construction skills, you can perform as little or as much of the work yourself.

Think of how much this type of deck would increase the value of your home. I know it has mine.

Want to learn how to install a glass railing system? Scroll down for more instruction.

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This article is another example of NBI's commitment to you and your clients. Our commitment to non-biased inspections allow us to write articles such as this. We don't build or repair decks; therefore, we're not in the business of replacing decks in the exact same manner that will cause them to rot, time and again.

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Installing a glass railing system

Go from THIS To THIS ! !

I have a very pretty view so I didn't want to reinstall wooden railing. I wanted to have as unobstructed view as possible and felt my choices were the steel cable system or a glass railing.

I chose not to use the steel cable system because it creates a potential safety hazard by making a "ladder" assembly for young kids to climb on. I went for glass panels with "powder coated" aluminum framing that won't ever rust.

At first I was a little apprehensive working with metal but soon found that it was much easier than wood.

Good planning and attention to detail is the key to success. I went on-line to compare deck railing suppliers. They had a lot of good information I was able to use. I was able to pick the size, style and color of the posts and top railing.

Installing railing is comprised of the following steps:

Drawing and measuring the deck
Ordering the railing
Installing the railing
Measuring and ordering glass
Installing the glass
Sitting back and admiring your work.

Create a drawing of the finished deck with "good" measurements (within 1/2"). (Since you will be cutting the rails to size...your measurements don't have to be exact at this point.)

This is all the railing supplier really needs. They will input your drawing into a CAD system that will compute the number of posts and the railing lengths that you need. (I chose to make all of my own calculations and create my own material list for added safety.)

HINT: Insist that you receive a completed drawing showing exactly where each railing is to be used. I had multiple angles on my deck ranging from 6' to 33' long. My supplier shipped the rails in 17', 18' and 22' lengths and (in essence) said...GUESS where these go. Mis-cutting a 22' top rail can be a pretty expensive mistake.

HINT 2: Make sure to inform the supplier that you are installing a 36" tall railing system allowed on a single family home...NOT a 42" railing system required for apartments and/or commercial buildings.

Plan ahead because it will take 2-3 weeks for the railing to be shipped. Add another week if you have a custom color. (You can place your order as soon as you have established the perimeter dimensions of your deck. You don't have to wait until the entire deck surface is completed.)

Install your posts first. You can have deck mounted posts or fascia (side) mounted posts. Because I had a slate tile surface, I chose to mount my posts to the side fascia boards. (I was concerned the posts would eventually break the tile.) Each post comes with a welded plate that is 6" long and extends to the sides 2". Each is pre-drilled for your mounting screws. A good quality railing system will have "welded" brackets for the top and bottom railing as well.

The posts need to be as close to perfectly square as possible since they support the entire framework. You will need to add shims behind the top or bottom of your mounting plates to achieve this. I used one or more strips of scrap plastic. You can use anything that won't rot.

Your posts should not be more than 5' apart. (Sometimes, you can fudge to 5 1/2') Your glass panels shouldn't be any longer than 60".

Once the posts are installed, you are ready to install the top and bottom rail. I used a "chop saw" with a carbide blade but a simple hacksaw would also work. Since your cuts slip into fittings, they don't need to be perfect.

The bottom railing into a "U" shaped cup. I cut my pieces about 1/4" short for ease of installation. I used one self-tapping screw to fasten it into place.

The top rail is mounted on top of the smaller posts. A small mounting bracket is screwed into the top of the post. The outer flanges are then screwed into the top rail track.

The finished rail has nice clean look. All fasteners are hidden.

The rail on the larger posts is placed inside cups that are about 1" deep. Cutting your top rail 1" shorter than the post-to-post measurement allows you to slip the rail into one cup and then slide it back half way into the other. I used one self-tapping screw to fasten it into place.

Next, you need to install the plastic glass track into the top and bottom railing. The top and bottom track is exactly the same; however, 2-3 rubber spacers are installed in the bottom track. (This is what the glass will rest on.) I cut 1-2" pieces and slipped them in from the end prior to installing the track. They slip into the track very easily with firm hand pressure.

Once the railing has been installed, you are ready to order your glass. Each panel needs to be cut exactly to your specifications and then be tempered. Once it is cut, it cannot be re-cut so it's important that you measure accurately. I received my glass within 10 days of ordering.

On my deck drawing, I numbered each panel between posts and then created a list using that numbering system. I then provided the supplier with the exact "opening" dimensions for each panel.

EXAMPLE:

Panel #1 60" wide x 30 1/4" high
Panel #2 54" wide x 30 1/4" high
Panel #3 39" wide x 30 1/4" high

I wanted a 2" air space on each side of the glass panel plus I added 3/4" to the height of the panel so it could slip into the upper rail and then back down into the lower rail. Using this formula, Panel #1 would be 56" wide and 31" high.

HINT: Insist that each panel of glass be marked with YOUR numbering system.

If you have created a sloping waterproof deck as I have, you will need to provide the supplier with the angle of the slope so they can cut those panels into parallograms.

The glass panels are simply inserted into the top rail and then slid half way back down into the bottom track.

HINT: These plastic tracks really grip the glass. Rubbing bar soap on the track made it a lot easier to maneuver the panels.

CONGRATS....your railing is completed. Now sit back...relax and enjoy the view.

MORE HINTS:

Shop for your best price. Contractors specializing in glass railing systems will charge $55-$70 per linear ft. depending upon how large your deck is. I found a supplier on-line that sold me all of the components for $34.00 per linear ft. Home Depot quoted me $56.00 for the exact same components from the same manufacturer.

It took less than 30 man hours to install my railing system and I saved well over $3500.00

VERY IMPORTANT! ! !

Choose a dark color for your railing. Initially, I had intended the railing to be white to match the trim on my house. I found; however, that a darker color railing system will "blend in" with the background far better than a lighter color. I installed my railing so I could enjoy my view....NOT look at the railing. The difference is incredible.