Grommets as drain holes in canvas awning?

We installed a large retractable awning over the patio a few years
ago. It works well except for one problem. If the awning is extended
when it rains, the canvas gets wet, sags, and a lot of rain
accumulates in the depression. So far, I have caught it before any
damage, but a couple of times a fairly large amount of water had
accumulated.
I am wondering if I should see about installing some kind of drain in
the canvas and, if so, what?
The awning is 20' wide and about 12' deep when fully extended. This is
the company that makes them and ours looks a lot like the ones on the
main page:
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time it rained pretty hard. I didn't notice that it was extendedfor awhile. When I did, the puddle was a long oval. The length wasabout 80% of the width of awning (so about 16'). The width was about2' at the widest. It was maybe 6-10" deep at the deepest point.
If I assume the volume to be roughly half of those dimensions on
average, I get something like 8' x 1' x .4 = 3.2 cu ft of water. At 62
lbs/cu ft, that about 200 lbs.
I would imagine that it can handle 200 lbs, but what if I am away? It
looked like it could have gotten a lot larger.
My first thought was to install a row of 3-5 small grommets about
6-12" from the end of the awning. I wouldn't think a very big hole
would be needed. I'm not sure how to install them. Aren't they usually
snapped together by a tool that needs access to both sides and a solid
base?
Reply to
Square Peg
How about just re-mounting it so that one end is a little lower than the other. It'll drain to that end.
Reply to
Bob F
On Fri, 26 Dec 2008 14:23:13 -0800, "Bob F" wrote:
Did you look at the link? The front is about 2-3 feet lower than the back when fully extended. That's more than "a little lower" and it's not enough.
The canvas is pretty straight when dry. When it rains, it gets heavier and starts to sag. Once it gets below the front edge, water starts to accumulate.
Reply to
Square Peg
That would be true if the awning didn't sag under the water, which is what usually happens. Also, it usually sags in the middle, not at the sides, and putting drain holes in the middle defeats much of the purpose of the awning. When I had fabric covered gazebos in my yard, I often had to go out and use a broom to push up the fabric so that the water (which is very heavy!) would run off the ends. I was ultimately defeated by four feet of snow, which collapsed both gazebo roofs and bent the metal structures. My new gazebo is cedar.
Reply to
Pogonip
I've seen grommets used in canvas for that very reason. I've never seen them used in awnings, but why not? Cheap brass grommets from a hardware or home supply store work. if you want nickel plated grommets, you can get them at a marine canvas supply house, such as sailrite.com, but nickel plated grommets are "star" grommets (star grommets also come in brass), which are much stronger AND require special (and expensive) dies to set them. In an awning you won't need the extra strength. I'd go with the hardware store grommets.
Reply to
jaxashby
Addition, yes you will have to take the awning down to set the grommets. A somewhat heavy die is set on a hard surface (say concrete), the grommet is placed one piece each side of the canvas, a somewhat heavy punch is set on the topside, and hammered home. Done.
A special hand operated tool is available to set grommets, but it goes about $140, plus about $40 for the die (each size grommet, star or plain), plus (if you want it) about $44 for the hole cutter (each size hole). For just 3 or 4 grommets you can cut the holes with an Exacto knife. By comparison, a die set/hole cutter/bunch of (cheap) grommets (of whatever size) goes about $15 at a hardware store.
Reply to
jaxashby
As I said, lower one END. So the water that backs up at the edge strip flows to the end and off the awning. Should be able to reduce the pool to a part of an inch.
If it sags even before the water pools, then my suggestion won't work. Unless of course, you drop the end even further.
A few, maybe useless ideas:
If it is possible to make the canvas tighter in the middle, and looser at the ends, the water would be more likely to find its way to the ends. Or, you could figure out a way to add some tight ropes from the top to the bottom under the canvas. The ropes alone could hold the canvas up, or some firm foam could be placed between the canvas and the ropes to lift the canvas enough to prevend pooling. (pool spagetti?) Perhaps ropes from each high corner to near the center at the bottom, so the lift is at the center where it pools.
Of course, a padded stick prop under the pooling point could fix it, but you have to remember to put it there, and the wind could flap the canvas enough to drop it.
Reply to
Bob F
Unless you plan to use stainless steel or any other type of non rusting metal, the grommets will rust and eventually eat away at the canvas. Also keep in mind, even if they don't rust, you risk the fraying of the canvas around the grommets since they are not sewn within the grommet area. Within time, the canvas will start to deteriorate under the weight of the water.
A solution is to simply remember to retract the awning when weather looks bad or when you plan to be away from home. I wouldn't mess with the integrity of the canvas.
Reply to
SBH
I used to make one end of awning little lower to make the water to run off. Don't keep it level(horizontal).
Reply to
Tony Hwang
Hi, Ever operated a RV or camping trailer? I used to have that big wning on my fifth wheel trailer. I I pull the awniing it is a common sense rule to make one end lower so water can run off canvas. Little off topic, you don't build a deck perfectly level for obvious reason. You never pour a drive way perfectly level for your garage.
Reply to
Tony Hwang
No matter how well you install grommet, it'll compromise the integrity of canvas. Even it may shorten the life of canvas. Just set one end of awning little lower than the other side to let the water run off. We campers do that with our trailer or motor home awnings. Just common sense thing.
Reply to
Tony Hwang
On Fri, 26 Dec 2008 16:44:30 -0800, "Bob F" wrote:
So that really is what you meant. That was my first impression, but I figured no one would actually suggest an awning that wasn't level.
If a 2-foot drop over 12 feet is not enough, how much do you think I should lower one end ort a 20-foot awning. Should I raise one end above the roof or lower the other end below the top of the window?
Yeah, like 5-6 feet.
Are you sure your name isn't Rube Goldberg?
Reply to
Square Peg
On Fri, 26 Dec 2008 19:46:37 -0500, "SBH" wrote:
I was planning on calling a canvas shop and a marine store after the holidays. We have both in this area. I'd go with whatever they recommend.
Well, that *IS* the plan, but my memory being what it is...
So I guess you would be against my second idea, which is to punch several small holes or slits in the canvas and skip the grommets. I wonder if I can "spread" the fabric with an awl and make a hole large enough for a slow drain. I don't think it will take much. They might tend to clog with debris, so I might have to reopen them from time to time.
Reply to
Square Peg
On Fri, 26 Dec 2008 17:59:15 -0700, Tony Hwang wrote:
See my reply to Bob F. All too often, common sense is neither.
Reply to
Square Peg
Having done some sailing, and knowing nothing about retractable awnings, I would worry more about wind than rain. 200# is a lot of water to hold. I did a google search and found a rain sensor for retractable, here:
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the installer still around? Can it be motorized, or change arms so it has more pitch if you will beaway?
Reply to
Norminn
Why not eliminate the real cause of the problem?
Check with a camping supply company or similar and get a canvas waterproofing product. If the canvas does not get absorb water and sag it will not hold puddles of water.
Charlie
Reply to
Charlie
On Fri, 26 Dec 2008 21:06:50 -0500, Norminn wrote:
Well, wind is also a problem.
I contacted the original installer. He said I shouldn't extend it when it rains. (duh)
Reply to
Square Peg
I agree with others that the Grommets may weaken the fabric, unless you sewed on a reinforcement layer.
Despite the put-down, I'll make one more suggestion.
From looking at the website, it looks like the arms that extend this thing out are probably not heavy enough to pull the canvas really tight, especially if there isn't an arm in the center. An additional "stretcher" added near the center, which could be added after opening the awning, would both hold the canvas up and pull it tighter in the center, perhaps alleviating the problem. Just a length of aluminum tubing with ends to allow it to engage the bottom strip, and wedge in at the top. A chunk of 2x2 would perhaps work for a test.
Reply to
Bob F
On Fri, 26 Dec 2008 19:34:27 -0800, "Bob F" wrote:
Put down? I was joking. Rube Goldberg is a very funny guy. I just wouldn't want him designing my awning.
You'll probably take this wrong, too, but I am not going to go out and wedge a piece of tubing to stretch the awning every timne I open it. For one thing, I don't always open it the same distance. It's also on the second floor. It shades the patio, but it also shades the room over the patio.
Reply to
Square Peg
"Unless you plan to use stainless steel or any other type of non rusting metal, the grommets will rust and eventually eat away at the canvas. Also keep in mind, even if they don't rust, you risk the fraying of the canvas around the grommets since they are not sewn within the grommet area."
and
"No matter how well you install grommet, it'll compromise the integrity of canvas. "
..............................................................................
Guys, **brass** grommets (the cheap hardware store kind) are COMMONLY used on boat canvas, __under stress__, or at least FAR more stress than an awning draining a bit of water. "Weather cloths" (USA term) or "Lee cloths" (Brit) are the canvas (usually Sunbrella) that are strung on the lifelines to the sides of a sailboat cockpit to protect the sailboat operators from (cold) winds and/or spray. They are typically strong enough so that sailboaters often use light string to hold the bottom edge, in case a boarding wave (from the side) strikes the boat. That way the bottom edge of the weather cloth comes loose, so that the (stainless) stanchions holding the lifelines don't collapse.
**Normally**, those grommets are put through a double layer of Sunbrella, with maaaaaybe a layer of webbing, but that is because boat owners like to pull weather cloths TIGHT. For __weather cloths__, those extra layers around the grommet are justified. For water drainage, no extra layers are needed.
FWIW, MAINsails (which develop enough power to push a 12,000 pound or more boat at 7 or 8 mph) usually have *brass* grommets (the strong kind), though some with have stainless grommets (more difficult to set, but look nicer for the customer who prefers stainless steel). In main sail applications, the luft (front edge of the sail) is usually several layers of resinated sailcloth, and most usually with a stretch rope sewn in as well.
Hand-sewn grommets for the luft attachment of a main sail are **reportedly** stronger than set grommets, but to the best of my knowledge no one makes them anymore (the rings are available, but the *brass* sleeves that protect the sewing thread from chafe are not). FWIW, last week I hand-sewed a 1-1/4" tack (front corner attachment) to a used sail for a customer (to shorten it a needed 2", because the sail was longer in the vertical measurement than advertised). It is time consuming, but the alternative is some expensive equipment that only dedicated sailmaking shops have. It DOES look salty, however. It also took $60 worth of die setting tools, a concrete surface and a 2# hammer. The only mainsails I have ever seen with hand-sewn grommets on the luft (leading edge) were OLD sails.
Cheap grommets (without extra layers of awning material) will work just fine for water drainage. It is commonly done on certain kinds of main sail covers which collect rain (which most main sail covers don't).
BUT, if you're really worried about grommet corrosion, you can unlay (unwind) a small diameter nylong rope, take one of those strands and twist itself back on itself to form a small circle, cut a small hole (Exacto knife) in the canvas, then sew around the rope/hole, one stitch close (on the outside), the next stitch out a bit, continuing around the rope/hole until complete, two ropes/holes sewn somewhat close together, then sewn (kinda) to each other. Rope handle attach points on canvas water buckets were once commonly made that way. I did it once, just to say I did it. Now, I use machine sewing and pressed grommets, or a sewn on canvas handle.
Reply to
jaxashby

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