7" gutters for metal building

[Shovelhead]

Any gutter guru's on here?

Got a bid for my 42x54x14 shop which has a 12' lean to porch on one side and 16' on the other.
I asked about down spouts.
Roof area from eave to eave is 70' .

They said 7" gutters with 2 down spouts.
I thought maybe they'd have a down spout on all four legs/posts.
He said overkill for a 7" gutter.

Then we talked about drainage. I want to connect 4" corrugated drain pipe to the down spouts and run it underground out to the woods.
He said they could slope the gutter and put the down spouts on the last two legs/posts closest to the woods. That would keep me from digging and running the drain pipe as far.

Other than appearance he said it will work like a champ. No different than having the down spouts on the end legs. Said if they were on the end legs they slope the gutter from the center out to each leg.

He made me think it makes sense, but wondered if anyone has any experienced input on the situation.

Photos of 16' lean to and where I'm draining the runoff.

Thanks

 

[mike93lx]

Don't use corrugated. It is garbage. Only benefit is that it is easy to install and cheap to buy.

It doesn't support weight, clogs up with garbage and is easy to tear.

Basic 4" DWV pvc is about $2 a foot and will self clear of debris and is easier to maintain slope when installing.

Personally, I'd want more downspouts. Pushing all that water to just two places seems imprudent, but I am no gutter expert.

My last house, a 28x52 ranch, had them at all 4 corners. Also avoids having the gutter slope oddly to one side

 

[Shovelhead]

The DWV pipe is certainly better and twice the cost. Also no problem for a "lawn" and a nice clean straight ditch. I've used both. . My drainage ditch will be far from straight due to all the trees. The flex pipe will be a helluva lot easier to install.

What size gutters were on your place? He claimed the slope wouldn't be noticeable, however, I tend to notice anything that ain't level and square with the world.

 

[mike93lx]

The DWV pipe is certainly better and twice the cost. Also no problem for a "lawn" and a nice clean straight ditch. I've used both. . My drainage ditch will be far from straight due to all the trees. The flex pipe will be a helluva lot easier to install.

What size gutters were on your place? He claimed the slope wouldn't be noticeable, however, I tend to notice anything that ain't level and square with the world.

I had regular residential stuff. 4", I think.

I have heard that there is a dual or triple wall pipe that has a smooth interior. Strength aside, corrugated clogs with debris and really can't be cleaned out

 

[XRlifer]

I just had 6"gutters installed on my 36x48 shop. Metal roof, and draining to all four corners with 2-50 foot runs. I was told, and i've read that 32' was as long of a gutter run you should have while only draining to one side due to the angle they need to drain properly. I've got to believe that having that drain only to one corner would look terrible, and I agree with previous poster that that's a LOT of water draining to one area.

 

[dcg9381]

There are calculators on the web to help you figure out what you need in terms of gutter and pipe capacity in various rain events and roof area. But the "net net" of a building that size in Texas (you might have more rain) is that you need big *** gutters and big *** pipes.

Just "eyeballing" that - it's a pretty big building. My 60' has 3 x 4" downspouts.

The issue that I read about off the bat is a 7" gutter with what I assume is a 4" downspout. Even if it's a 7" downspout, it's going to transition to a 4" pipe... Plan for the smallest transition.

Here's one calculator (didn't use it): http://apps.smacna.org/dsgcal/


We've used corrigated with success for about 12 months on the house, but the shop gets 4" PVC, as that water flows into our water tanks. Anything over 4" gets expensive fast.

 

[Shovelhead]

I've got to believe that having that drain only to one corner would look terrible, and I agree with previous poster that that's a LOT of water draining to one area.

Don't really disagree but it would actually be draining to two down spouts not just one on the end.
When you say one area, do you mean where the underground drain pipe would end or the roof area in to the gutter?

I really want to drain everything to the back through the woods to the creek. If I run any of it towards the front I'd have a lot of underground pipe to get clear of my drive.

 

[Shovelhead]

Thanks dcg9381.

I'm no expert but sure seems to me the overall runoff ought to be split evenly between down spouts.
How's that water going to know to let half it's friends run by the first spout and run to the last one if they're both on one end?? LOL

-- 4"x5" down spouts

 

[theoldwizard1]

My SWAG ! 6" gutter and downspouts. At least 4. If you are going to run it underground, that pipe should be at least 6", 8" is better.

 

[egdede]

Thanks dcg9381.

I'm no expert but sure seems to me the overall runoff ought to be split evenly between down spouts.
How's that water going to know to let half it's friends run by the first spout and run to the last one if they're both on one end?? LOL

-- 4"x5" down spouts

Water is predictable, doesn't like to share and takes the path of least resistance. So, the first one takes the closest hole. The second takes the second hole, it is a little further, but it is empty. The 3rd takes the 1st hole because they are both already full, but the 1st hole is closer. An so on....

 

[jack stand]

Go with his suggestion if you're inclined to. Re adjusting half of the gutter later for a spout on each end and adding another d/s is simple if your not happy.

 

[u2slow]

My eave length is about 40' collecting off ~40x30' on each half of the roof and 1 downspout isn't quite doing it because the gutter slope isn't enough - it floods. I need to add a downspout at the other end too.

 

[ycgoat]

I am just a DIY so not an expert by any means, but my building is 80x30 and I am going to slope each 80 ft length from the center to a down spout in the corners so each down spout would need to cary the water for a 40'x15'-6" roof area. The land does slope from one end to the other so I will have to protect from erosion on the ground.

 

[u2slow]

Putting in an extra downspout is a good time to consider rainwater collection, if that's worthwhile for you. (It is for me.)

 

[CraigStu]

I have never had a building anywhere near the size of yours but every home I have ever owned had 4 downspouts. I guess his point about 7 inch gutters has some validity though. Jack stand's thought about adding them later may work out but I'd need to see how he is attaching the gutter because it may not be easy to move those brackets. Still, I'd prefer 4 downspouts.

 

[Shovelhead]

CraigStu, there will be 4 downspouts. Just not on the very ends. The 7" gutters is what made me immediately say no way I don't like that idea.

I have another guy that I'll get a bid from and see what he recommends.

This first company been in business 40 yrs and flat out told me they would likely be higher priced than my next bid. Said they have 5 full crews with bending/rolling machines whatever they are for seamless gutters. An office staff that actually answer the telephone and claimed if any problems they send someone out in less than a week to make it right.

That means a LOT around here. I'm in the sticks and getting anyone to do anything is a major challenge.

Obviuosly I don't want to have them come out to re-rig it all.

Was hoping ole "redhead" on here would chime in with some thoughts. I know he's put up many metal buildings.

Thanks

 

[dcg9381]

Thanks dcg9381.

I'm no expert but sure seems to me the overall runoff ought to be split evenly between down spouts.
How's that water going to know to let half it's friends run by the first spout and run to the last one if they're both on one end?? LOL

-- 4"x5" down spouts

Depends. You control the runoff to the spouts by the slope of the gutter. It's just about being able to control the volume of water on the sloped roof area per spout. I agree with you that "most efficient" is even distribution - but depends on what you're trying to do, how big your gutter capacity is and how much you can discharge by spout...

There may be nothing wrong with a 7" gutter that has 2 4" downspoints on one end if you need to do it that way.... Just depends.

Most of my "spouts" are 6" "leaf eater" collectors attached to 4" PVC. That works for about 98% of our rainfall conditions. There are conditions where I'd need 6" pipe...

 

[CraigStu]

Ah, I see now. I must have missed the 4 downspouts. Sorry for that. And I agree, finding a good local company to do work for you will be worth it in the long run.

 

[Jeepster04]

Ah, I see now. I must have missed the 4 downspouts. Sorry for that. And I agree, finding a good local company to do work for you will be worth it in the long run.

Post #1 says 2 down spouts, post 16 says 4... Not sure how many it will have...

7" gutter is massive, so its possible it would work with 2 3"x4" downspouts... My house has 5" with just 2 2"x3" downspouts for ~60'... That does NOT work. The heavy downpours will overflow it every time. I've considered adding another 2x3 downspout right beside of one on the end to see if that would help. Im not replacing the entire gutter.

 

[scofo]

Hey Shovelhead, I see you are in Texas. Check out Texas tax code Sec. 151-355 and Texas sales and use tax exemption form 01-339, used for water conservation and collection. Might save you some money??

Goodluck.

 

[Toolfool]

I did 7" gutters and 4x5 downspouts on my 46x48 building. Gutter guy said 4 downspouts would be fine. As I was burying the 6" SDR35 drain pipes I decided to add a third downspout. Only had 6x6x4 sanitary tee-s left, so went with 3x4 downspouts for the extra ones. I have always added more downspouts than the gutter guys recommend. I've never seen one of them stopping by in the middle of a rainstorm to check on the drainage.

 

[rburke65]

After buying the 7” , 2 extra down spouts are inexpensive assurance

 

[Shovelhead]

Post #1 says 2 down spouts, post 16 says 4... Not sure how many it will have...


2 per side makes 4.

 

[rancherbill]

I agree with the guy. A 54' 7" run will carry a heck of a lot of water. Remember there is going to be a slope of 2-4 inches. Get him to put a pipe from the front to the back where you want it to drain.

 

[nadogail]

The corrigations in your flex lines will act like riffels in a sluce box and trap high density particulate matter.

 

[CN Spots]

Not of much help on your downspout issue but one thing I would tell them is to not mount the dang gutters so far under your roofing sheets that you can't get your hand in there to clean them out. Mine only have about 2" of space between the metal roof lip and the outside edge of the gutters. Makes it impossible to clean them.

 

[Shovelhead]

Not of much help on your downspout issue but one thing I would tell them is to not mount the dang gutters so far under your roofing sheets that you can't get your hand in there to clean them out. Mine only have about 2" of space between the metal roof lip and the outside edge of the gutters. Makes it impossible to clean them.

Very good point.
We have a cover over the back porch at our other place and it's the same way.
I just have to use my leaf blower and chase the stuff around til it jumps out.

 

[mike93lx]

Good gutter guard are amazing.

 

[johnharris]

A 3x4 downspout can handle 800 sg ft roofing max. If each side is less than 1500 sg ft than 6" gutters with a 3x4 downspout on each corner would be enough.

My cousin is installing 6" gutters on my shop tomorrow. Being 30' gutters with 525 sg ft roofing I'm just having him put one downspout on each side. They'll be mounted on the back side running water down the hill.

 

[johnharris]

Very good point.
We have a cover over the back porch at our other place and it's the same way.
I just have to use my leaf blower and chase the stuff around til it jumps out.

If the metal roof is hanging too far for gutters ask them to cut some off. My cousin uses battery powered turbo shears to cut a few inches off when needed.

 

[welder57]

In your neck of the woods-(2) Extra Downspout-may be roof saver when a flooding rain comes.