Roof drainage, no gutters.


  #1  
Old 11-10-03, 04:49 PM
MattG_
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Roof drainage, no gutters.

I am currently exploring options on my low-pitch, built up roofing, and hoping to improve drainage and ease of maintenance. I don't know squat about roof design, but it seems odd that the roof has no guttering or drip edges. Instead, water is supposed to exit in holes (skuppers i guess they're called) located in each roof corner, connected with downspouts. The roof design is pretty simple, 1 ridge, 2 hips, no valleys. The roof is not raised along the edges to prevent water from pouring over and it seems obvious that rain water hitting the middle of the ridge is not going to run to the corners of the roof. Its going straight down to the edge of the roof along the path of least resistance. Am I missing something here? Perhaps that is why the roof is in good condition except along the edges and facia, where deck and facia rot has occured. Would it be wise to install a gutter system, either on the facia or atop the roof?
 
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Old 11-14-03, 03:57 PM
Grumpy
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Scuppers are common for flat roofing with parapet walls. I don't know what type of roof you have, but what you described isn't a flat roof.

In a wintery area the bottom edges and valleys of the roof are first to go. Those are the areas that hold the most snow. Valleys wear away quickly, all things considered, because they funnel the most water.

I couldn't say you should install gutters because I am having a hard time invisioning your roof. Any chance you could post some pics or a sketch of the house?
 
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Old 11-15-03, 08:25 AM
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Hi Matt,

Check out this link, graphics are a bit crude, but you should be able to put a name on the type of roof you have, which will help us give you some good informed advice.


http://www.cmhpf.org/kids/Guideboox/RoofTypes.html

Post back with the type of roof you've got & we'll get ya lined out.
 
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Old 11-15-03, 12:23 PM
MattG_
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Roof design

Thanks for your replies Grumpy and Awsomedell.

The roof is a simple gable design with the only interruptions being one large skylight and one plumbing vent pipe. I haven't measured the pitch, but probably not more than a couple inches of rise per ft., definitely not flat, no parapets or any kind of curbing on the edge, but definitely shingling is out of the question.

You're right Grumpy, the drainage holes are not scuppers (I discovered a flat roof diagram on the Internet after posting my message). Drainage is accomplished by holes (about 3" id) cut in each corner of the roof. A downspout (sealed with roofing tar) runs from the roof's surface, thru the eaves, out of the soffits and to the ground. I'm not sure if this can be improved on: gutters or some type of curbing. Quite a bit of water drips from the roof's edges, but the edge's are in such poor shape (rot and water puddling) I'm not sure where to pinpoint problems.

Also I'm taking a serious look at rubber surfacing as opposed to the BUR that is currenly in place and the foundation is slab concrete. Thanks again.
 
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Old 11-15-03, 12:32 PM
Grumpy
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Sounds maybe like an inset gutter system? Do you have a dig. camera?

If they are inset gutters, we've removed them and boarded over many times. Depending on the age of the house you may have 3-5 layers of customer bent gutter ontop of each other. If you remove all this and start over you get a much deeper gutter.

Also you can remove all of it, board over it and move the gutters to the outside of the fascia.

Obviously this all depends on my assumption that the gutters are inset.

BUR and concrete is typical for flat roofing, but you said there are hips and sridges.
 
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Old 11-15-03, 01:37 PM
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Have you give any thought to replacing your existing roof with a new metal roof. I've done a few, and they are really gaining in popularity here in central mo.

Here's the best link I could find quickly on google to illustrate the type of roof I'm talking about. http://www.inexsystems.com/html/metal_roof_systems.html
They're calling it a zip-ribbed metal roof, mostly referred to as propanel here in my area, you can get all the accesories for soffets, fascia, hip & ridge, what ever you need.

As far as costs, material is slightly higher, install labor is just a bit cheaper, benefits I see are as long as your trusses are sound and not sagging, you go right over what's there, which eliminates the mess & cost of tear-off & removal of old roofing materials. A layer of sheeted foam insulation is normally installed under it, which deadens sounds, so it not like the old fashioned tin roofs, and this also helps with heating & cooling costs. Also it's very durable & will most likely out live you & your grandkids!

Stuff is sold locally at lumber yards, Do-It-Best affiliates all sell it I'm sure.
 
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Old 11-16-03, 06:08 PM
Grumpy
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Awesome off subject a second. Did you know all your posted url's show up as code for me and not links? I wonder if anyone else has this problem.
 
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Old 11-16-03, 06:10 PM
Grumpy
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Originally posted by awesomedell
benefits I see are as long as your trusses are sound and not sagging, you go right over what's there,
Is that possible? Wouldn't the new metal roof appear wavy if applied of shingles or shakes or some other un-even roofing material?
 
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Old 11-17-03, 05:17 AM
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Actually you run furring over the top of the existing roofiing material, I've used 2"x2" the first one I did, but now use 2"x4", for a wider fastening surface.

Just depends on the day for the links posting correctly. Some days they work fine & some days they appear as the string of code. Not my department, I really don't know what causes it.
 
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Old 11-18-03, 09:33 PM
Grumpy
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Good to know. We don't usually install that type of roofing, so I wasn't familiar... makes sense.
 
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Old 11-19-03, 08:45 PM
MattG_
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Roofing over existing

Awesomedell,

You mentioned laying the metal and sub materials right over the existing roof. Since I have rotted decking along the edges of the roof (clean thru and gaping hole in two spots), and probably rot in the facia and soffit, wouldn't it be wise to replace the old rotted wood before putting on the new roof? I would think an ex-infantry grunt like myself still has enough back and grit left to do some of the work. Rip off the old myself and rent a dumpster for a couple hundred bucks.

Regarding metal roofing. I've considered it, but got the impression it would be a lot steeper in price compared to rubber. Would love to have it though. Can't wait to pull up the plastic and get this project done, that's for sure. Seems as if it's rained every other day lately.
 
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Old 11-21-03, 02:19 AM
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MattG,

With the kind of damage you've describing, it should definitely be ripped up & redone otherwise you'd be throwin good $ after bad!

If you do decide to come back with a rolled roofing product, I'd suggest going with something heavier than 90lb roll. Awaplan made by Tamko is a real good product to use on a low sloped roof like you're describing yours to be. But honestly if it was mine, I'd spend a little extra & go with the metal, it'll last a lot longer!
 
  #13  
Old 11-22-03, 09:08 AM
Grumpy
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It's not what you spend, It's what you get. I always do a cost breka down when purchasing.

If roof system A costs $1000 and lasts ten years, you know your cost is $100 per year.

If roof system B costs $1500 but lasts 20 years, you know your cost per year is $75 per year.

If you can afford the initial expense, go with roof system B.

The point I was trying to make was NEVER use a 90 lb. roof. The manufacturers don't even warrant it. To the best of my knowledge it doesn't even have a rating.
 
 

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