A freeze-resistant downspout system includes a metal downspout having an interior portion within a building and a contiguous exterior portion outside the building. The exterior portion is shielded from the weather by a thermally insulated shroud so that heat conducted along the downspout from within the building is sufficient to keep the exterior portion from freezing.

BACKGROUND OF THE INVENTION 
This invention relates to building construction, and more particularly to a 
freeze-resistant downspout system. 
In cold climates, downspouts can freeze up, so that water backs up in the 
gutters, overflowing them sometimes on the building side, whereupon water 
flows down or into the building. The weight of the accumulated ice and 
water can also damage the roof drainage system, or the roof itself, and 
falling gutters or downspouts are a danger to those below. Downspouts may 
also fail at their seams as ice expands within them. 
There are a number of solutions to the freezing-gutter problem, none of 
them perfect. Downspouts may, for example, be electrically heated to 
prevent freezing. Another known method is to place the downspouts within 
the building, where it is warm, to keep them from freezing. When this 
approach is used, the gutters may also be placed inside, but then any 
gutter leaks become quite serious. The alternative is to have interior 
downspouts, but exterior gutters. Such an approach requires a through-wall 
connection between the gutters and the downspouts. That connection is the 
subject of this invention. 
SUMMARY OF THE INVENTION 
An object of the invention is to prevent downspout freezing, by placing the 
downspouts within a building, while preventing water leaks within the 
building. 
Another object is to prevent ice damage to gutters, downspouts, and 
supporting structures. 
Another object is to prevent an exterior downspout portion from freezing, 
even when outside temperatures are frigid, without using downspout 
heaters. 
These and other objects are attained by a freeze-resistant downspout system 
including a metal downspout having an interior portion within a building 
and a contiguous exterior portion outside the building. The exterior 
portion is shielded by a thermally insulated shroud so that heat 
transferred along the downspout from within the building is sufficient to 
keep the exterior portion from freezing.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
A freeze-resistant downspout system embodying the invention is shown in 
FIGS. 1-3. 
The building shown in FIGS. 1 and 2 has a wall 10 and a roof 12. A gutter 
14 is attached to the eave 16 of the roof by bolts or screws along its 
inner edge, and by cantilever brackets 18 at its outer edge, as shown in 
FIG. 4. Water which collects in the gutter escapes through one or more 
downspouts 20, only one of which is shown in FIGS. 1 and 2. The upper end 
of the downspout terminates in a collector box 22, situated right below an 
opening 24 in the gutter, and affixed thereto by rivets or the like. 
The collector box 22 is a rectangular parallelipiped, having an open top, a 
round opening in its bottom, and four vertical walls. A short collar 30 is 
welded or otherwise affixed to the bottom wall, around the opening. 
The downspout has a 45.degree. elbow 26 extending from a hole in the bottom 
of the collector box, and then a straight segment 28 which leads 
diagonally through the wall to a further downspout segment, not shown, 
connected to a storm sewer or the like. Thus, the uppermost portion of the 
downspout is outside the building, while the remainder is within the 
building, protected from the weather. 
Where it passes through the wall, the downspout is supported by a wall jack 
32, which is a reinforcing plate having a cross-sectional shape conforming 
to the wall corrugations. Besides supporting the downspout, the jack 
provides a weather seal where the downspout enters the building. The 
jack-to-wall interface is weather sealed, preferably by applying Butler 
Manufacturing Company's "Panlastic" tape sealant (a non-hardening 
butyl-based tape mastic) around the perimeter of the wall jack, between it 
and the building wall. 
The collector box 22, the elbow 26, and the exterior part of the downspout 
segment 28--that is, the entire exterior portion of the downspout--are 
shielded from the weather by a shroud 34 having three vertical sides, and 
a sloping bottom 36 parallel to the axis of the straight segment. 
Consequently, the two parallel sides of the shroud are trapezoidal in 
shape. The top of the shroud is covered with a sheet metal closure (not 
shown) whose main purpose is to keep birds from nesting in the shroud. The 
bottom of the shroud has a vertical flange 38 which is affixed to two wall 
corrugations. There is a small open space 40 at the bottom, between the 
corrugations, to permit incidental drainage. The shroud is insulated all 
around with, for example, a one-inch layer 42 of rigid insulation such a 
"Thermax" board (a rigid polyisocyanate foam board having aluminum foil 
facings, produced by Celotex Corporation). The insulation is bonded to the 
interior surfaces of the shroud by an adhesive. The insulation helps keep 
the collector box and elbow above freezing. 
The invention may be applied to an existing building by cutting a slot in 
the wall panel, for the downspout to pass through. A collector box is then 
installed on the gutter, laterally aligned with the slot. A tape sealant 
is then applied to the wall, around the opening, and a downspout is 
connected to the gutter box, with the straight segment passing through the 
slot. Now, the wall jack is attached to the wall using blind fasteners 
such as Butler Manufacturing Company's "Lock-Rivet" fasteners. Finally, 
the shroud is secured to the wall, around the collector box, by means of 
self-drilling screws. 
During cold weather, the downspout conducts heat from within the building 
toward the gutter. This heating is usually sufficient, with the insulated 
shroud in place, to keep the portions of the downspout outside the 
building free of ice, without the use of an auxiliary heater. 
The heat transfer rate may be increased, if desired, by removing some of 
the wall insulation around the point of wall penetration by the downspout. 
One could further increase the downspout heating by forming air passages 
through the wall, into the shrouded volume, so that there would be 
convective heat transfer as well as conduction. 
Since the invention is subject to modifications and variations, it is 
intended that the foregoing description and the accompanying drawings 
shall be interpreted as only illustrative of the invention defined by the 
following claims.