Embedded Files
ION Field Operations
Site Survey
Non-Prefab Roof Structures
- There are an assortment of
non-prefab roof structures that may have been built.
Sometimes these structures are referred to as “Stick
Framed” roofs as each piece of lumber was cut on site and
individually put into place when the home was being
constructed.
As with Prefab trusses the size and spacing of the rafters
needs to be captured in a picture with a tape measure
showing the dimensions of the rafter (2x4, 2x6, 2x8, etc) and
the spacing of the rafters. Spacing for stick frame rafters are
usually 24” inches on center or 16” on center but could be
spaced at any distance.
In addition to getting the rafter size and space the ceiling
joists also need to be measured and their orientation to the
rafters noted. Are the ceiling joist perpendicular to the rafters
or parallel?
Often a “Side View” sketch is needed of the roof structure
when it is stick framed. Side View sketches are a way to
clearly show the dimensions and spans of rafters and roof
support structures.
ION Field Operations
Site Survey
There are couple common attic support
structures that need to be documented.
●
Knee Walls
- Are similar to purlins but
instead or kickers or struts holding the
horizontal support in place, vertical
studs more closely spaced together
give the structure support. Knee walls
are also often part of a finished attic.
●
Collar Ties
- A horizontal piece of
lumber that goes in between two rafters
that are on opposite sides of of the roof.
When Collar Ties are used they are
usually spaced every one for every
rafter.
Knee wall
Collar Tie
ION Field Operations
Site Survey
●
Purlins
- Purlins have a
horizontal support that is
supported and held into
place by struts or
kickers. Purlin struts
usually spaced every
other rafter, and extend
to the ceiling joist above
a load bearing wall
bellow the attic.
●
Finished Attics
-
Usually found in older
homes finished attics
are rooms that are built
into the attic structure, a
crawl space off to either
side that can sometimes
be access to the
exposed rafters.
Purlin
Finished
Attic Crawl
Space
Finished Attic Crawl
Space Entrance
Purlin Strut
ION Field Operations
Site Survey
Pictures and a detailed description of any damage
in attics needs to be included in site surveys. Make
sure the exact location of any damage inside an
attic is noted on a site map or clearly understood
from looking at the pictures or reading notes.
Common damage to look out for includes..
●
Cracked or broken lumber
●
Water damage
○
Note if the leak has not been repaired
●
Mold or Dry Rote
●
Asbestos
●
Open Air Splices
●
Bent or Bowing Roofs
ION Field Operations
Site Survey
●
Vaulted Ceilings
- Ceilings
without an attic space the indoor
ceilings are angled matching the
roof pitch. Basically the rafters are
directly below the roof decking
and then drywall built directly onto
the rafters.
●
Flat Roofs
- Roofs with no pitch.
The load bearing walls are the
support for the roof structure.
Often with flat roofs a load bearing
wall sketch needs to be completed
so that a structural engineer can
check check if it will meet
structural requirements.
Flat Roof
Vaulted Ceiling
ION Field Operations
Site Survey
In some regions side view sketches are required to
determine if a structural retrofit is needed.
Structural retrofits are when additional lumber is
installed on the roof structure to accommodate the
additional weight of the PV system.
Side view sketches show measurements from a
side profile. To the right is an example of a side
view sketch and sections that need to be
measured.
Dotted lines indicate measurements that need to be
obtained. Physically getting these measurements
may required moving between crawl spaces and
living spaces. Some attic structure cross sections
may also include vaulted ceilings with walls acting
as the structural support. It may take a little bit of
Unsupported Span
Unsupported Span
From purlin strut
to exterior wall
Strut Length
Unsupported Span
Unsupported
Span
Unsupported
Span
Collar Tie Length
Knee Wall
Height
From Knee Wall to
exterior wall
Side View for Purlin
Type Attic Structure
Side View for Knee
Wall and Finished
Attic Type Structures
ION Field Operations
Site Survey
If a home has a flat roof a load bearing wall sketch may
be required. A load bearing wall sketch is the rough
outline of the home with measurements for the load
bearing walls located throughout the home. The
objective of a load bearing wall sketch is similar to the
a side view sketch. The critical information that needs
to be communicated is the unsupported span lengths,
measuring in between the load bearing walls gives the
distance of those unsupported spans.
In addition to measuring the distance between load
bearing walls, the direction of the rafters needs to be
determined and documented for the entire home.
Rafter direction is not always consistent throughout the
home.
Door and entry ways with a “Header” supporting the
rafters above can be shown as a solid wall. Things like
small closets also do not need to be included. It is often
helpful to do a walk around the home before getting
measurements to get the basic shape of the building
and rooms sketched before starting to add
measurements. Keep in mind clarity is important but
the sketch does not need to be to scale.
185”
inches
165”
inches
102”
inches
96”
inches
108”
inches
98”
inches
72”
inches
112”
inches
215””
inches
165”
inches
155””
inches
113””
inches
202””
inches
65””
inches
142””
inches
86””
inches
Direction
of
Rafters
Direction
of
Rafters
Direction
of
Rafters
Direction
of
Rafters
ION Field Operations
Site Survey
As with all surveyed roofs the rafter size and spacing needs to be
confirmed with pictures. This can be a challenge with flat roofs. It
often takes a little determination and creativity to find a good
location to gain visibility of the rafters. If there is no hatch that
gives access the the roof substructure there are a couple locations
where visibility might be obtainable.
●
Recessed Lighting
- Can lights can be removed and the
hole where the can light was installed used as an access
point to gain visibility of the rafter size and spacing.
●
Remove soffit
- Sections of soffit can be removed to reveal
the rafters behind them. Care needs to be taken to not
damage the soffit while removing or reinstalling it.
●
Cut a hole
- As a last resort and with the customers
permission a small hole can be cut into the ceiling large
enough to take a picture of a tape measure up against the
rafters can be cut. ION will have the hole repaired
●
Wire Probe Test
- Very small hole is drilled just big enough
for a stiff wire to be inserted until it stops or the edge of the
rafter is detected by a small hook shape at the end of the
wire. The depth that the wire was inserted is measured to
get a rough idea of what size the lumber behind the ceiling
is. While this method works it is easy to get bad
measurements with wire probe tests.
Using a stud finder to
find the direction and
spacing of the rafters
and painters tape to
mark and measure
ION Field Operations
Site Survey
If the proposal shows ION is installing on a
detached structure such as a barn, garage,
pool house etc.. all the same information
gathered for a main homes also needs to be
gathered for that detached structure.
●
Ground level
○
Photos all around the detached
structure showing wall space
●
Service Entrances
○
Pictures of underground or
overhead power entrance into
structure
●
Electrical
○
Any and all service panels
supplying the detached structure
with power
●
Rooftop
○
Rooftop conditions and array
sketches
●
Attic
○
Rafter measurements pictures
and sketches.
ION Field Operations
Site Survey
In addition to getting all the standard information for detached
structures pictures and measurements from the detached
structure to the main home and main service panel are
needed.
When installing on detached structures there is the possibility
that a trench will need to be dug to run the PV circuit to where
it is will be interconnected with the home electrical system.
Include pictures showing a potential trenching path. Taking
these pictures from an elevated position like the rooftop in
many cases is a helpful angle.
If there is power running to the detached structure finding and
documenting how the power is being supplied is critical. A lot
of the electrical details should be retrieved completing the
standard electrical information. For detached structures it is
also important to get pictures and measurements showing any
existing conduit or cable running to the structure.
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