1 TH12 Location of problem drain over TH12 (see site diagram for location)
2 TH12 Columbia River Roofing fixing drain. The TPO membrane has a stiff fold as it enters the drain bowl riser and the pressure clamps came off and plugged the drain.
3 TH12 When clamps came off it allowed the folded membrane to close the pipe orifice and plug the drain. A new interior membrane was installed into the drain as shown.
4 TH12 covering internal membrane w/ finish membrane
5 TH12
6 TH12 covering internal membrane w/ finish membrane
7 TH12 Installing drain screen cover

Proposed replacement of the current scuppers

Diagram showing roof drains      and scuppers

Harrison West Condominium Re-roofing Townhouses Drainage Problem

The roof drain over TH12 has been problematic over this past year. Recently over 8” to 10” of standing water acumulated over the drain and no relief was noticed.  The overflow channel and scupper should have relieved the plugged drain.

Columbia River Roofing came on 4/21/23 to investigate and correct the drain issue over TH12.

But here is an assessment of the two problems that contribute to the ponding:

1) The scuppers were set several inches too high in relation to the roof drain and overflow channels

2) Lack of periodic maintenance allows the overflow channels to fill with debris, primarily maple wings, which impede waterflow.

When I reviewed all five of the townhouse roof scuppers, they were all installed in the same manner, as indicated in the remaining photos, to the left

RECOMMENDED SOLUTION

Fabricate a new scupper configuration that will lower the bottom of the scupper about 4" to 5", so that the overflow drain can relieve the ponding water when a drain clogs again. The mockup above, and at the top of the page, shows how we propose to lower the scupper, without having it extend below the drip line of the upper fascia panels. It proposes placing the scupper at the bottom of the mounting panel, to gain every inch.

Maintenance is another problem. All of the channels were clogged with maple seed wings--not leaves--which do not blow away and insidiously find their way even through the type of screens at TH2, TH9 and TH12, and potentially into the drain pipes.

Issue 1: The roof drain over TH12

Photo: courtesy of George Zelznak

8 TH12 Drain 12 overflow scupper
9 TH12 the bottom of the scupper is set at the top of the sloping insulation that was installed to drain all water to existing drains. This insulation line at the perimeter parapet is anywhere from 8” to 12” above the drain...
10 TH12 the scupper will drain water from a plugged drain only after it reaches between 8 to 12” of ponding water over the entire roof! This is a major concern for structural loading of the 22 foot span of the 2X12 joists
11 TH12 overflow channel looking back to the roof drain at TH12
12 TH12 view through the scupper looking back to the drain
13 TH9 overflow scupper on TH9
14 TH9 overflow scupper on TH9 with dam clearly visible at the end
15 TH9 roof drain bowl screen
16 TH6 (for orientation, see site diagram for location)
17 TH6 overflow channel and scupper
18 TH6 overflow channel and scupper with the dam clearly visible at the end
19 TH4 the 2nd drain and overflow scupper, draining to the west--this is the only building that required two roof drains, due to its length
20 TH4 No, this is not a scene from 'Indiana Jones,' featuring huge carnivorous beetles--the overflow channel is simply filled with maple seed wings and organic gloop before Patrick tried to clear it out with his boots.
21 TH4 overflow channel and scupper, mostly cleaned out.
22 TH4 roof drain bowl screen --note that this is the anomaly
23 TH2 (for orientation, see site diagram for location)
24 TH2 drain, overflow channel and scupper as an overview
25 TH2 roof drain bowl screen
26 TH2 overflow channel and scupper
27 TH2 overflow channel and scupper with the dam clearly visible at the end

Issue 2: The scuppers and overflow channels

Scupper at TH12

Scupper at TH2

"All maples produce samaras, but red, silver and Norway maples often produce the largest quantities. These seeds will rain down on lawns, decks, roofs and gutters in many locations. These can become a nuisance, especially if they clog gutters and down-spouts or germinate in garden beds."

MSU Extension

Scupper at TH9

Scupper at TH4

Scupper at TH6