# Flat roofs - rain drainage



## iaviksfan (Dec 27, 2007)

I have built over the winter, some buildings with flat roofs. There is no way for rain water to drain off of these. I was thinking of just drilling a few holes in the back so the water can drain off. Other ideas?
Thanks
Greg R.


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## FlagstaffLGB (Jul 15, 2012)

Morning Greg, 

Being an Architect for more than 30 years (in this hobby for a little bit more), flat roof tops don't really exist in real life...minimum slope and scuppers are used to get the rain off...but of course, we are modeling buildings for a garden rail road and things aren't always done the way a roofer would want them to be done. Ha. Not sure exactly what material you used for the roof deck, but if it won't hold up under standing water, then off course you need to get it off. To get some slope to the roof, I would suggest not making the foundation or base when you have it outside not level...give it a slight angle (2%) to the rear. Probably won't be noticed. Now if you built these structures with a parapet around the perimeter of the roof, then this won't totally solve the problem, it is going to still hold water, just to the rear of the structure. Since real roofs would have scuppers, then you could "drill" or cut small holes at the rear of the parapet to allow the water to run off the roof. 

A second set, which could be critical if you have a parapet wall above the roof level, would be to put a bead of clear silcon caulking between the parapet wall and the roof...otherwise the moisture is going to seep between these two surfaces and eventually warp the wood or other materials and then you'll have gaps. With a little care, this could be painted to patch the roof surface and look the way a real rolled or hot mop roof is applied. Don't know how much rain you get (location is an obvious indicator), but if all else fails and if you don't have too many buildings with flat roofs, you could always put some plastic trays over the top of the buildings when you aren't running trains or during rainy weather. Internal roof drains can also be incorporated, but depending upon the size of the buildings, it might not work for you. Good luck....


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## placitassteam (Jan 2, 2008)

I have several buildings with flat roofs. The above answer pretty much covers things, but I thought you might like an example. On this church I drilled through the parapet and inserted a piece of brass tube. I did this before stuccoing the building, but you could the same thing and just caulk around it. You could also use a square tube if you like that better. Good luck with it.








The 2 little tubes you can see near the top of the wall are what I am talking about.


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## iaviksfan (Dec 27, 2007)

Guess i could have mentioned it, but these are Colorado Model Structure kits. Thanks for your ideas, Greg R.


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## grsman (Apr 24, 2012)

I built one building from Smith Pond Junction that had a flat roof. It was the Grand Junction Saloon.
The roof was designed with about a 1/4" slope from the front to the back.
There were scuppers designed into the back of the roof. It looks realistic and works.
http://spjrr.com/sp/
Tom


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## NTCGRR (Jan 2, 2008)

I drill holes for vents any way and it won't hurt anything if it falls through onto the ground. 

Architect??? I guess we can be friends. LOL 
Come to think about it, I have not built any flat roofs (so to speak in 1:29th ) that did not have atless one side low to allow run off. 




























The top roof top stairway is a drain going down to a hole in the base. also I install 3 screens in my windows to allow air flow on HOT days.


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## vsmith (Jan 2, 2008)

Hey Marty, whats wrong with the Artichoke business? Got over 25 years in that field myself. 

Unfortunately if you plan structures out doors you have to treat them just like real but smaller buildings. Water penetration seams to be a prime reason all outdoor structures deteriorate (UV exposure being number one). I would see if you can drill a couple holes in the side parapet walls where the water pools most. These would act as scuppers and allow the water to escape. It doesn't take much.


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## iaviksfan (Dec 27, 2007)

Nice building Marty.


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## Greg Elmassian (Jan 3, 2008)

The only problem with scuppers is that your 1:1 leaves and blossoms and etc. are not to 1:29 scale, so your "scuppers" will plug easily. 

You have to make them larger than scale, and a bit of screen over them helps. 

I'd try sloping the roof and have gaps in any parapet walls as a higher priority. A single dandelion "frond" can plug a scale sized scupper. 

Greg


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## mgilger (Feb 22, 2008)

I cut corner sections out to create an area for the water to drain out. I initially place the building where I want it, level it and spray some water on the roof to see where the water pools. I then pick a suitable area to cut the notch close to the pool. See the following building, lower right corner, middle of the back wall and another one that's hard to see, in the left lower corner above the rail car entry door.

To cut the notch I simply use a pair of Diagonal Pliers and cut two vertical pieces down to the level of the roof. Then I take a regular pair of needle nose pliers and bend the cut piece downward and it will break right off.Touch up with a little paint so it matches the roof and it's finished.

Regards,
Mark


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## iaviksfan (Dec 27, 2007)

I like that idea better than drilling holes.... Thanks 
Greg R.


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