Hi guys,
I was looking for some opinions on how some of you might properly drain a blacony/wrap around 2nd floor deck as shown in the pic attached.
This is a second floor wrap around deck/balcony. The largest portion is roughly 10ft x 38ft and the rest wraps around from front to side of the house at about 6ft deep.
There is 18 inches of space to work with from first to second floor, giving the space needed to properly supply hidden drainage under the decking.
I have a basic idea of how I plan to accomplish this…
I plan on creating a slope towards the home so that all water leads to a channel / flashing that sits up against the home and then into a scupper. and sitting on top of this slope sits a floating deck which would be constructed to correct the level of the floor. Areas of the deck around the installed scuppers would be constructed either in smaller units so I can simply remove that whole portion of the deck and joists for scupper cleaning or I would cut out that portion of deck and reconstruct the decking as one piece and place it back on the exposed joists .
There are some problems i see myself running into however. One being that the joists I use for my decking would be sitting directly on top of my “drainage pan” i ahve created underneath it and so water would be in contact with the joists during rains. unable to be treated after decking installation was complete. Also I intended to use a white pvc membrane to seal this drainage area… would the wooden joists which are simply resting on this pvc be a problem long term?… should I wrap these joists in a membrane of some kind and take care fo both my problems?
Or perhaps there is a much better system entirely than what I have suggested?
How it gets down I dont care as long as
1.) It doesnt leak
2.) I can easily access and clean the scuppers underneath decking
Replies
I plan on creating a slope towards the home so that all water leads to a channel / flashing that sits up against the home and then into a scupper.
I'd question running the water toward the house. What's your plan to dispose of it? A scupper is a flashed horizontal hole through a wall. I'm not understanding your exit strategy here.
Areas of the deck around the installed scuppers would be constructed either in smaller units so I can simply remove that whole portion of the deck and joists for scupper cleaning
I agree with that idea.
would the wooden joists which are simply resting on this pvc be a problem long term?... should I wrap these joists in a membrane of some kind and take care fo both my problems?
We typically glue a strip of the membrane to the bottom of the sleepers. . If using the proper lumber, I'm less concerned with deterioration of the sleepers than I am with them damaging the membrane from load movement and thermal expansion/contraction.
What kind of deck is it? Is it a concrete deck or wood joist deck? Anyway, directing the water toward the house wall into a channel is bad idea. You are assuming the channel is always going to be cleaned conscientiously and also the water is going to drain just so into the channel. For example, a quick downpour may not drain as you wish.
Also, don't depend on stick on membrane or caulk barrier to protect the structure. If your joists or other structural parts are not PT, you should think of it like a roof and go with rubber membrane cover or such. All the dust, leaves, bugs and other debris will help hold moisture. Hope it helps.
I think I am going to build this system the same way the flat roof on my house will be done. If it works up there why wouldnt ti work under my decking. Or is that wishful thinking on my part?
1/4 pitch with IB Roof system installed. Just as they would flash and seal parapet walls on my roof I can treat the exterior wall of the home and the interior side of my balcony knee wall. Drains and downspout placed where need be
That is not wishful thinking. That is how roof decks are done. !/4" per 12" slope is better than usual 1/8" slope. I am assuming that you want to hide the drainage system from the front view, and that is why you want to put the drainage against the house. But again, I think it is bad idea. You can't assume your vision will continue to work year after year and in the worst case scenario. Drainage away from house is one of those tried and true ideas. For example, if your scupper happens to get blocked in a storm, you will have a lake right by your doors and wall.
There was article in FHB about somebody building a deck just like yours and flashing with epdm membranes. It also showed, I think, how to flash the scupper holes.
The rubber membrane needs to be protected from the decking.
The scupper does not have to be common. Look for photos of gutterless rain drainage (one I remember is hanging sort of chain from the gutter so that water follows the chain down). Decorations are built into the structural parts all the time, such as dressing up the rafter ends. Scupper is a basic box, so you may be able to find photos of gutters or scuppers that were built with art in mind. Using copper, even if expensive, may be one way to go.
hope it helps.
Thx K1c
Ya, i am looking to keep the system hidden away like you mentioned. IB roof systems custom makes the scuppers for you with pvc membrane already welded in place... I love their system and if you do some searching on you tube they have installation videos of pretty much any scenario you can think of.
I am strongly considering the opinions of you guys saying don't put it on the house side.. In the end I will probably take your advice...once i convince myself :)
As far as keeping the decking off the membrane:.. If I glued membrane to the underside fo the joists.. will that be sufficient or is the rub from membrane vs membrane still too much? There will be rub because I do not plan on fastening the joists to teh floor. I need them to be removable to keep the drain and subfloor clean
If I glued membrane to the underside fo the joists.. will that be sufficient or is the rub from membrane vs membrane still too much?
I've never done PVC membrane, but the 1st EPDM roof I used that detail on is 24 years old. The deck structure has been replaced.
I need them to be removable to keep the drain and subfloor clean
Best idea you've had. Keep that in the plan.
IB roof systems custom makes the scuppers for you with pvc membrane already welded in place... I love their system and if you do some searching on you tube they have installation videos of pretty much any scenario you can think of.
Of course they do. They're selling their product. But that doesn't necessarily mean it's the best way to do it. Usually more than one way to skin a cat. I typically stick with time tested methods over "new/improved" when it comes to rain handling.
bp
I understand the need you see to access the drainage system/scuppers. But, removing decking and joists seem like a lot of work for a maintainance plan. I think you should at least consider a system of frame and waterproofing that sits apart from your deck covering. Seal, flash and provide a base under your finish materials. Include in that base something that raises the finish up off your membrane. Construct this so you can lay panels of assembled decking on top.
Personally I would even stay away from a panel system. Some of the exotic woods and certainly the composites get pretty heavy, and then where do you put them while you clean the underside?
imagine 6'x6' sections of decking built and placed on the floor.. I can easily move 6x6 sections. Not something I plan to do more than a few times a year anyway. I will move one or two sections at a time, clean and replace. I've done the same thing before with 8x8 sections for a family members vacation home... they needed a deck that could be moved
JLC just did an article on this. They had a specific product that sat on top of a membrane and was adjustable height - all plastic too. They built 2' square sections of deck to go on top.
http://www.bisonip.com/home.asp?pid=2