- Q.What is the best way to attach gutter
downspouts to a house with EIFS?
A.John Edgar, senior technical services manager
at Sto Corp., a manufacturer of EIFS systems, responds: To
fasten something light to an EIFS wall, you will need screws or
lag bolts long enough to reach through the rigid foam to the
sheathing or framing. You’ll also need a PVC sleeve
(plastic tubing or conduit) with an interior diameter a little
larger than the fastener. The sleeve allows the installer to
tighten a screw against a solid object without crushing the
Fastening an object through EIFS will be easier if the
sheathing under the foam is plywood rather than gypsum. If the
sheathing is plywood, use the following procedure:
1. Mark the location of the fastener on the finish.
2. Drill a hole through the EIFS up to — not through
— the sheathing.
3. Line the hole with a neutral-cure caulk. (If the caulk
smells like vinegar, it should not be used. A vinegar smell
indicates an acid-cure caulk, which may corrode the
4. Cut a length of your PVC sleeve about 1/8 inch longer than
the thickness of the EIFS, and insert it into the hole. The
sleeve should be 1/8 inch proud of the EIFS. Tool any excess
5. Fill the sleeve with additional caulk and immediately fasten
the downspout through the fresh caulk in the sleeve. Remove any
If the sheathing is gypsum, the only locations where
fastening is possible are at studs or blocking. Follow the same
procedure described above. If it is necessary to fasten between
studs, a toggle bolt may work. Of course, before drilling
through any wall, be sure that there are no electric wires or
gas lines in the area.