ELBOWS - seal with sealant or duct tape?

[MNRebecca]

Tried to walk the dog between storms yesterday and got caught in a downpour which yielded unexpected results. I saw something I might otherwise never have known about. When the rain comes down really hard, water backs up out of a downspout elbow, shooting into the air like a fountain (to land in a vulnerable, leak-inducing area) instead of continuing along the long, extended horizontal downspout track* to drain away from the house/foundation. Before I look into wider downspouts and elbows, I'd like to try sealing thoroughly. What will work better, duct tape or gutter sealant?

*Downspout runs the length of the house, about 40 feet (with one additional 90 degree turn besides the elbow) before spilling onto the lawn to run down a hill. This was necessary as the neighbor's property, just a few feet away, slopes down towards my house. No room to effectively release water without navigating the length of the house.

[RicodJour]

Downspout components are generally not sealed. You have to clear the blockage and there won't be a need to worry about a sealant.

That is a horrible setup. If you have to dig a drywell to handle the rain water, then that is what should be done.

If your gutters clog frequently - with a 40' run and a 90 degree bend I'm sure they do - you should definitely have something like Leafguard gutters so they won't get clogged with leaves.

R

[DT]

Larger downspouts will sure help. If you have the standard 2x3 size, you can go to the 3x4 size. If the 40' horizontal run is not real visible, replace it with pvc pipe. I have a similar situation, I use 4" pvc to run 36' across the front of the house, but it is under the porch so it doesn't show.

[Bobk207]

R-

You don't have a sealing problem, you have a "blockage problem". Forty feet of "downspout", really drain line, and two elbows are probably a little excessive...so the water is backing up & pressurizing the joint that you see spraying water. You could (when its dry) seal the joint wiht aluminum tape but that's only fixing the symptom. You need to make sure your the drainline portion of your run is free of obstruction & when clean, it is able to handle the necessary flow.

If cleaning (bust open the joint & blast the drainline clean with a hose) fixes the problem, you're done. If not consider replacing the drainline portion of the "downspout" system with a 3" or 4" plastic drainline. Dump the real downspout into the new drainline. Ideally you'll need ~10" of drop for the drainline....if you have less, this might be the cause of the backup.

If you go with the drainline fix, use a sweep T fitting with a cleanout to make maint easier.

cheers Bob

[Dave]

So the downspout is effectively point up, not down, in this region?

What type of roof do you have?

[MNRebecca]

Thanks, all, for the help. I'm intrigued by the idea of a T sweep fitting, something easier to clean than the elbow I'm going to have to pry loose (not much give built into the system I set up). Dave, the downspouts never point up (as I understand your question).

[MNRebecca]

Well, I checked for blockages last night. None. I confess I'm a little bummed. My house isn't that big... 1,800 sq. feet. Is it logical that even a smaller home can have 'too much roof for the gutters' in heavy downpours? By the way, Dave, the roof is shingled with shangle shingles. The part where I'm presumably getting more water than standard downspouts can handle is an area with a cathedral ceiling over 2 inside vaults (one over a dining room and one over a living room whose vault is perpendicular to the adjoining dining room vault).

RW

[RicodJour]

If you're sure there's no blockage anywhere in the downspout (or where it enters the ground, if it drains underground), that simplifies things. You need a larger downspout and possible a larger gutter as well. You can have a handyman cut a larger hole where the existing spout is now and fit a 3x4 downspout to replace the existing 2x3. It's kind of hard to believe that the original installer would think that a single 2x3 spout could handle 40' of roof. Typically there are two 2x3s on a 30' run, so you're close to a 2/3s undersized downspout arrangement.

Is there any water cascading over the front edge of the gutter anywhere along its length?

R

[MNRebecca]

Nope. That happened a while back when, to my shock, the downspout hole in the gutter clogged just two weeks after being checked (and despite my use of gutter guards) and the gutters began overflowing in a downpour (after two years of drought, all we get is downpours!). I scooted up quick and unclogged it. So, when all is clear, the gutters can handle the load from a downpour, but the downspout, at the elbow, can't, and the rain shoots up out of the top of the elbow.

[Bobk207]

The additional info you have provided seems to confirm that the vertical down spout section coupled with the "horizontal section" (ie the drain line) cannot handle the flow.

IMO a larger down spout & drain line is indicated. The larger down spout will be less prone to clogging & and the larger drain line will give less back pressure to the system.

If you want to get technical, you need the area of the roof that is drained by this gutter, down spout, drain line combination....armed with this info AND a estimate of the peak rain fall rates you've been experiencing (inches per minute or a peak rate of inches per hour converted to inches per minute)

This will allow you to calc the maximum flow rate through your system

But on the other hand since the gutter doesn't over flow & nothing is clogged........ you could just seal the elbow joint to prevent the errant spray and forget about changing anything.

The additional pressure head built up by the rising water in the down spout (which causes the spray) actually generates a self regulating system.........the increased pressure increases flow through the drain line and balances the rainfall run off. Seal the joint & the immediate issue goes away.

Dry the joint, clean with acetone & seal with aluminum tape. Or a section of inner tube (or EPDM roofing material) & hole clamps.

It all depends on how you want to handle this.

cheers Bob

[Dave]

Then its confusing to me how the downspout is shooting into the air... IE V E R T I C A L. Can you further define what you're saying???

If you don't have enough downspouts to accomodate the gutter, it will overflow during a heavy downpour. Doesn't matter about outlets to ground system drainage and so forth. It will only confuse the location of the actual problem if unaware of that. Dog chasing his tail, if you will. Dave

[Bobk207]

Dave-

Based on what she has posted as answers to others' questions, I believe she has a situation with marginal downspout & drain line capacity.

In times of heavy rain, the water backs up in the down spout due to drainage restriction from that 40' horizontal drain line section. When the water backs up into the down spout, the down spout / elbow joint is submerged & pressurized. Due to this pressure, the water squirts out the joint.

She says she doesn't get gutter overflow, this is because as water rises in the down spout the pressure heads increases & thus the drain line flows more water.

She has a situation that seems to work, except for the water squiritng out of the joint.

cheers Bob

[Dave]

So, the water rising/gushing out is in fact coming from a joint in a horizontal guttering that was never meant to move water horizontally and in such substantial manner.

Maybe some adaption to 4" drain pipe in the picture might alleviate the back pressure? Dave

[MNRebecca]

I suspect the (essentially) 90 degree angle of the elbow, coupled with its narrowness, is a large part of the problem. I thought to myself, "What if I found a wider, longer, flexible elbow, so that the heavy flow of water didn't have to make such a narrow, tight turn? Maybe I could hack off a bit of the downspout and make the turn into the horizontal pipe more gradual, less constricted." The fountain effect is happening right above the top of the elbow, after all. But crap, the downspout is anchored to the house way down low, so low there's no room for anything but a 90 degree turn. I'm not crazy about the idea of abandoning the use of anchoring (it's a windy area on that side of the house)... or of drilling new screw holes higher up (it's REALLY windy on that side of the house).

[Bobk207]

R-

Don't be too hasty to make permanent changes.

Of course I cannot see your installation from here but I doubt that the elbow alone is all (or even most of the problem)

Any chance of a picture?

I'd put my money on the 40' horizontal run. I mentioned this earlier but I think it got missed......how much elevation change does the drain line have over the 40 feet? It needs about 10"......5" could work but without sufficient, drop the water won't move very well.

You say the down spout is anchored "way down low" does the land fall on the way to the lawn?

cheers Bob

[MNRebecca]

Um... none. The downspout goes all the way down the wall of the house and gets anchored to the house about 9 inches above the ground. There's just enough room to attach a 90 degree elbow, which attaches to the LONG horizontal 'pipe' (actually several sections of extra downspout linked together AND making 1 additional 90 degree turn). I sure see your point.

[willshak]

Not good. Just think how fast, or slow, the rain runs through the gutter, and the gutter has, or should have, a pitch. The water in the horizontal section has to be pushed out, more or less, by the following water, rather than just running out on its own. Also, the horizontal section is more likely to be clogged by debris washed down in light rains.

[BobK207]

I think we know all the information we need to diagnos & make suggestions.

Like I said before you need 10" (more or less ideal) or 5" absolute minimum to make your gravity feed drain line work. The water that backs up into the vertical section of the down spount is creating the prssure to make the system work....but it also causes that errant jet spray.

So...........

1) seal the joint with aluminum tape (eliminate the jet spray) & forget about it or 2) cut the down spout about 10" shorter and give the drain line section some slope.

either method will work

cheers Bob

[MNRebecca]

Thanks again for all the help, folks!

[BobK207]

Rebecca-

Let us know how it turns out when (if) you make an changes and how it does during the next downpour.

cheers Bob