Instructions / Assembly

Even though Ondura is easy to install, before begin-
ning, you should thoroughly read these instructions to
understand how they apply to your roofing or siding job.
We recommend you have an architect or structural
engineer check your roofing plan for soundness and
especially for proper ventilation.
Thank you for buying Ondura – the corrugated roofing and siding
material that brings you both good looks and long life.
Please use extreme caution on the roof to insure your personal safety at all times. Be sure that ladders and other such devices are safely posi-
tioned and properly secured. OSHA recommends the use of a safety harness when applying roofing. Protective eyewear is recommended
when applying fasteners or using power tools. When walking on Ondura, wear soft-soled shoes and place your feet perpendicular to the
corrugations. All roofing is slippery when wet, dusty, frosty or oily...avoid working or walking on the roof if any of these conditions exist.
Working on the roof if windy conditions exist can be dangerous and should be avoided. And, like any asphalt product, refrain from walk-
ing on in high heat.
GETTING STARTED
Slope & Purlin
Spacing
Slope describes the steepness/incline
of the roof. A higher slope value indi-
cates a steeper roof. A 3” in 12” slope
desribes a roof where the slope rises 3
inches for every 12 inches from the eave
to the peak. We recommend a 3˝ in 12˝
slope, or steeper, for satisfactory instal-
lation of both Ondura sheets and tiles.
For sheets, these instructions treat a 3˝
in 12˝ slope (or greater) with purlins
(supports) spaced 24˝ on center (o.c.);
for residential applications, a similar
slope over solid decking is required.
For sheets, this 24˝ purlin spacing
should be reduced under certain cir-
cumstances. For example, in areas of
heavy snow loads or potential snow
drifting on a roof section, purlin spacing
should be reduced to 18˝ or 12˝ on cen-
ter. (When in doubt, we recommend
that you consider the more narrow spac-
ing. Ondura can provide you with spe-
cific load test data to assist in your plan-
ning.) Do not use 16˝ on center spacing.
On curved roofs, the purlin spacing
must be reduced to 18˝ or 12˝ in the
low slope areas near the top.
Another instance when purlins
should be spaced closer is with slopes
less than 3˝ in 12˝. Space no more
than 18” on center at 2˝ in 12˝ to 3˝
in 12˝ slopes. Also, two-corrugation
side-laps may be necessary.
Wherever extreme weather condi-
tions are possible or buildings have an
interior ceiling, solid decking with felt
or ice water shield are required.
We do not recommend installation
on roofs with eave-to-peak distances
greater than 80´ unless the roof slope is
3˝ in 12˝ or more. We do not recom-
mend installation on any roof
with less than a 2˝ in 12˝ slope. Purlin
spacing greater than 24˝ can cause seri-
ous problems and is not recommended.
Plan For Adequate
Ventilation.
Poor ventilation can cause severe heat
build up in the summer or condensation
in the winter that may cause deterioration
of roof framing and covering materials.
Positive ventilation, along with addi-
tional insulation, can prevent condensa-
tion. Figure 24 suggests ways to assist
proper ventilation by taking advantage
of the corrugated design of Ondura
sheets and tiles and by using Ridgeline
®
Ridge Vents.
We strongly suggest, however, that
you check your ventilation plan with
a qualified engineer or architect before
beginning installation.
Suggestions For
Ventilation
Ondura’s corrugated design and
vented closure strips allows for some
air flow. For optimal ventilation, use
Ridgeline Ridge Vents with Ondura
solid closure strips. Use Ondura vented
closure strips at the eave.
Ondura, like all roofing materials, should be carefully
installed. Mistakes in installation can cause roof prob-
lems later on. So take your time and closely follow
these installation guidelines. As you can imagine, they
cannot cover all possible situations.
Quick Estimating Guide For Tiles.
Roofing Materials:
Tile Dimensions = 48˝ W x 19 3/4˝ L
• Tilestocoverasquare:24
 • AveragenumberofOnduranailsneededpertile:12average.
 • Averagenumberof3˝Onduranailsneededpertile:Tilesinstalled 
  alongeaveandridgerows:12pertile.Othertiles:3pertile.
 • Ridgecapsare6´7˝long.Allowingforend-lapsof7˝,theactual 
ridge coverage is 6 linear feet per cap. Ridges can be cut into
fourths to achieve a tile effect, this reduces the coverage to
56 linear inches.
Accessories:
 • Closurestripsneeded:Totalthelengthininchesoftheeavesplus 
twice the length of the hips, ridges and valleys. Divide the total
inches by the closure strip length of 44 inches to get the number
  ofclosuresneeded.Thenmultiplyeaveandridgemeasurements
by 2; hips and valleys by 4.
 • Onduramoldedpipeflashingaccessoryforhotorcoldpipes.
See page 8 for additional information.
Note: For more information, check with your Ondura dealer.
Quick Estimating Guide For Sheets.
Roofing Materials
Sheet Dimensions = 48˝ W x 79˝ L
 • Sheetstocoverasquare,4.5(3.8sheetsequal100squarefeet
of material). Allow extra material for multiple hips and valleys.
 • Nailsneededpersheet:24averageand38perridgecap.
Use only genuine Ondura nails.
 • Ridgecapsare6´7˝long.Allowingforend-lapsof7˝,theactual
ridge coverage is 6 linear feet per cap.
Accessories
 • Closurestripsneeded:Totalthelengthoftheeavesininches
plus twice the length of the hips, ridges and valleys. Divide
the total inches by the closure strip length of 44 inches to get
the number of closures needed.
 • Skylights:48˝x79˝7oz.heavy-dutytranslucent-whitefiberglass.
 • Onduramoldedpipeflashingaccessoryforhotorcoldpipes.
See page 8 for additional information.
Note: For more information, check with your Ondura dealer.
2
Tools & Materials.
AllyouneedtoinstallOnduraarethefollowingtools:
 • ClawHammer
 • SteelTape
 • Chalkline
CAUTION:Avoidinstallationwhenthematerialtemperatureisbelow35º
 • String
 • NailApron
 • UtilityKnife
• Electriccircular
saw with carbide-
tipped blade