FAQ - Roofing | Allsteel Inc.

Does it Cost More to go with a Different Panel Profile?

We do not charge a different price for each panel profile, we price an order based on what material is used (26g, 29g, etc.).

Why should I prep my roof?

Any irregularities in the roof, including uneven plywood joints, warped plywood, uneven trusses, poor application of underlayment, the use of button caps with felt paper, etc., can promote oil-canning. Oil canning is a wave-like, rippled appearance extending up the length of the panel after it has been installed on the roof. Care should be taken to provide a flat, uniform surface on which to attach the panels.

How do I install my roof?

Panel installation should begin at the gable end of the roof opposite the prevailing rain-bearing wind (this will provide added protection against wind-driven rain being forced under the laps). Measure one panel width from the roof edge. At this point, chalk a line from ridge to eave. Place the leading edge of the first panel along this line. It is extremely important that this panel be laid square to the eave and ridge so that the remaining panels will line up square on the roof frame. It is recommended to have a person at the eave and at the ridge to ensure that the proper panel coverage is being maintained across the roof. Also, be sure that the panels are properly side-lapped.

In applications where end-lapping is necessary, the upper panel on the slope should lap over the panel that is lower on the slope by about 12 inches. Lesser roof pitches require a greater amount of panel overlap. All end-lap applications should use 2 horizontal rows of butyl sealant tape across the panel and proper fastening to provide a maximum water seal.

An overhang of 2 to 3 inches on the eave is recommended to provide a drip edge, while only 1-inch overhang is necessary where gutters are used. The open panel ribs at the eave can be sealed with inside closures. For maximum weather tightness, a row of butyl tape can be applied above and beneath the closure material.

How do I cut the panels?

To cut panels across the profile:

The best devices for cutting steel across the profile are either hand snips or a nibbler. Carborundum blades on electric saws have a tendency to leave hot metal particles that can

either burn the painted surfaces or leave rust marks on panels and trim. The same is true of any filings left on the roof caused by the application of screws. Care should be taken to brush particles from roof surfaces after application.

To cut panels lengthwise:

Carefully mark where the panel is to be cut, and, using a straightedge, score deeply down the length of the panel with a sharp-pointed utility knife. Folding the panel along the score mark, and bending back again if necessary, should produce a clean break in the panel.

WARNING—Clean all metal shavings and particles off the roof to avoid rust stains.

Do I need to keep my materials dry?

All Allsteel panels and trim are designed to withstand severe rain and wet weather conditions. Neither painted nor Galvalume finishes are designed to be in continuous contact with water for long periods of time. Damage will result if uninstalled panels or trim are allowed to remain wet in storage. Be sure to store material that will not be installed immediately in a dry location. Wet material should be air-dried and re-stacked if installation is not planned right away

How do I calculate and place screws?

Allsteel carries screws in 2 different lengths: 1½ inches and 2 inches. The 1½ inch variety is the best all-purpose size. The table below can be used to figure approximate quantities of screws for various purlin spacings and sizes of roofs. Screws are available in quantities of 250.

SCREW (purlin) SPACING

linear ft of panels
in your order                     12 inch     18 inch       24 inch
50                                          270          180          135
100                                      540              360          270
200                                      1080          720          540
300                                      1620          1080          810
400                                      2160          1440          1080
500                                      2700          1800          1350
600                                      3240          2160          1620
700                                      3780          2520          1890
800                                      4320          2880          2160
900                                      4860          3240          2430
1000                                      5400            3600          2700
1100                                  5940          3960          2970
1200                                  6480          4320          3240

Again, be sure to clean away any metal shavings left after applying screws to the panels to prevent rust stains.

What is a Pipe Boot?

Pipe boots provide a watertight seal around roof vents and come in a variety of sizes. They seal with caulk and conform to the shape of the panel ribs.

How do I measure and order roof panels?

Care should be taken to order panels of the correct length to avoid having to take corrective measures after purchase. Panel lengths should fall 2 to 3 inches short of the ridge when a vented ridge is desired, and should extend 2 to 3 inches past the eave to allow a sufficient drip edge (except when concerning gutters). When a roof transition is involved, panels of the upper portion should be ordered short to allow placement of the transition flashing.

How do I find my roof pitch?

The angle or pitch of a roof is calculated by the vertical rise for every 12 inches of horizontal extension. The roof pitch is a measurement of the roof's rise in relation to its horizontal measurement, known as the run. This is also referred to as "rise over run." For instance, a roof that rises 4 inches for every 12 inches of run is expressed as a 4/12 pitch.

What are the different types of roofing styles?

Gable Roof: This is one of the most common roofing styles. It consists of a pitched triangular roof with two sloped slides.

Hip Roof: Another standard roofing style, the hip roof has four sloping sides forming a ridge along the top.

Gambrel Roof: Gambrel roofs slope down symmetrically on two sides, first at a shallow angle and then at a much steeper slope.

Flat Roof: A flat roof is just that - flat with minimal slope.

Single Slope Roof: This type of roof has a single pitch in one direction.

Lean-to: A lean-to roof, or shed roof, is a single, sloping surface attached at a higher end to a wall or a building’s main roof.

Can I install metal over shingles?

You cannot install metal directly over shingles. You must have a barrier between the metal and the shingles.