What information do you have on fabrication and installation guidelines for ACRYLITE® extruded (FF) acrylic sheet when used in glazing applications?

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What information do you have on fabrication and installation guidelines for ACRYLITE® extruded (FF) acrylic sheet when used in glazing applications?

Cutting by Scribing

Cut ACRYLITE® extruded (FF) sheet up to 3/16" thick as you would cut glass. Don't remove masking. Use a scriber - a scribing knife like the one pictured, a metal scriber, an awl, or a sturdy craft knife - to score the sheet. Draw the scriber several times (7 to 8 times for a 3/16" thick piece) along a straight edge held firmly. Cut carefully using firm, even pressure. Continue each stroke cleanly off the sheet's edge.

Clamp the sheet or hold it rigidly under a straight edge with the scribe mark extending just beyond the table edge. Protect your hands with a cloth and wear safety glasses. Apply a sharp downward pressure to the sheet's overhanging edge - it'll break along the scribe mark. Scrape the edges to smooth sharp corners. Avoid this method for long breaks or material over 3/16" thick.

For more information, refer to Fabrication Tech Briefs #2, "Cutting with Circular Saws," and #3, "Other Methods of Cutting".

Interior Applications — Windows

Because interior applications are not exposed to wind pressure, you can use thinner sheets than normal for window glazing.

Opening Size Recommended Thickness
Up to 12 sq. ft. 1/8"
12 to 32 sq. ft. 3/16"

Temperatures don't vary widely in interior applications, so provide half the expansion allowances given for window glazing.

Exterior Applications — General Recommendations

  • ACRYLITE® extruded (FF) sheet is not as rigid as glass. Follow the thickness recommendations below.
  • ACRYLITE® extruded (FF) sheet's expansion coefficient mandates clearances between the frame and the glazing panel. Cut panels shorter than the frame outside dimensions to provide the spaces listed in the table under "Exterior Expansion Clearances:"
  • Provide a channel or rabbet depth large enough to prevent the sheet withdrawing from the frame during high winds or cold weather. The rabbet must allow the sheet to expand in summer.
  • Install the panel without bolting so it can expand or contract.
  • Use sealant compounds and tapes flexible enough to accommodate thermal expansion and contraction. You can use mechanically held, approved gaskets such as EPDM, Santoprene® (registered trademark of Monsanto Corp.) and Closed-cell Neoprene as sealing materials.

Exterior Applications — Thickness Recommendations

The thicknesses in the following drawing apply to rectangular windows with widths less than ¾ their lengths installed vertically. For larger widths, use the next larger thickness. For long, narrow windows whose length exceeds four times their width, use the next smaller thickness.

At a design load of 30 psf, glaze a 48" x 36" window with 3/16" thick sheet. For a 76" x 48" opening, use ¼" thick sheet; for a 30" x 12" opening, specify 18" thick sheet. Consult local building code offices for load requirements in your area. These thicknesses apply to vertically installed windows only. If your installation is subject to a typical wind load above 30 psf, refer to the following table.

Thickness for Outdoor Applications 30 - 40 psf Design Load

Window Size ACRYLITE® extruded (FF)
Sheet Thickness
1-5 sq. ft. 3.0mm (1/8")
6-15 sq. ft. 4.5mm (3/16")
15-32 sq. ft. 6.0mm (1/4")
32.5 sq. ft. 9.5mm (3/8")

In most places, specify a design load of 25 to 40 psf for windows up to 30 ft. above ground level. At low elevations, ground drag reduces wind velocity; thus, design one-story building windows for lower wind pressures. As a rule, assume wind velocities from 100 - 120 mph equal design loads of 30 to 40 psf. The relationship between wind velocity and wind pressure is:

P = 0.00256 x V2

In the equation, P = pressure in lb./sq. ft. against a flat surface perpendicular to wind direction, and V = wind velocity in mph. In choosing design wind load, consider building height and safety.

Exterior Expansion Clearances

The tables below are for installations in the mid-temperature range (55-75°F or 7-22°C). If you're installing in extreme temperatures, or the installation is likely to encounter extreme humidity for long periods of time, use the formula for thermal expansion and contraction and humidity expansion in the example on page 3.

Expansion Clearances for Colorless Sheet (Mid-temp Range)

Opening Cut ACRYLITE® extruded (FF) sheet shorter than outside frame dimension by:
Up to 36" 1/16"
36" to 65" 1/8"
65" to 90" 3/16"
90" to 117" 1/4"
117" to 144" 5/16"

Expansion Clearances for Darker / Colored Sheet - Transmission 60% or less

Opening Cut ACRYLITE® extruded (FF) sheet shorter than outside frame dimension by:
Up to 27" 1/16"
27-45" 1/8"
45-63" 3/16"
63-82" 1/4"
82-100" 5/16"
100-117" 3/8"
117-135" 7/16"
135-144" 1/2"

For an opening of 48" x 72", cut colorless ACRYLITE® extruded (FF) sheet 47-7/8" x 71-13/16: and dark-colored sheet 47-13/16" x 71-3/4".

Sash Design and rabbet Depth

You don't need rubber setting blocks under ACRYLITE® extruded (FF) sheets. If you use them, allow block and expansion space. Because of gravity, all vertical expansion or contraction may occur at the frame top. Make the top rabbet deep enough for total expansion and contraction.

The rabbet depths listed below allow for fore-shortening by wind deflection. Use standard extrusions if they meet requirements.

Channel (Rabbet) Dimensions

Long Side of Panel Minimum Rabbet Depth (D) Minimum Rabbet Width (RW)
24" 7/16" 3/8"
36" 5/8" 3/8"
48" 3/4" 9/16"
60" 7/8" 11/16"
72" 7/8" 3/4"
84" 1" 3/4"
96" 1 1/8" 3/4"

NOTE: Rabbet width = thickness of ACRYLITE® extruded (FF) sheet + space provided for both sealant beads. See the drawing above.

Exterior Installation Instructions

NOTE: If there is any question about the compatibility of materials with ACRYLITE® extruded (FF) sheet, contact Roehm America LLC.

  • Adjust, plumb, and square framing or sash.
  • Remove rabbet projections to provide uniform clearance and prevent point loads.
  • Clean aluminum sash with VM&P naphtha to remove grease and protective finishes.
  • Seal sash corners and intersections for a watertight sash.
  • Prime-paint all sealing surfaces where necessary.
  • Measure opening precisely.
  • Figure expansion clearance from the Expansion clearances tables above and deduct from the opening to determine cut sheets size. Cut to size accurately.
  • Remove protective masking before placing the panel in the sash, or roll back masking edges.
  • Remove masking right after installation to prevent bake-on by the sun.

Exterior Glazing - Small Lights - Both Dimension 24" or Less

  • Thickness of ACRYLITE® extruded (FF) sheet can be 1/8".
  • Frame: use wood, metal, or rigid PVC with 7/16" minimum rabbet depth.
  • Clearance: cut the light 1/16: shorter than the opening, allowing expansion.
  • Glazing Methods: Face glaze or channel glaze using approved elastic (non-hardening silicone) glazing compound or butyl calk (for channel glazing only).

Apply enough glazing compound so it oozes out after you've pressed ACRYLITE® extruded (FF) sheet into the opening. Center the light in the sash, bed the removable stop in a face glazing design, or fill in the front edge of a channel-glazing design, or fill in the front edge of a channel glazing with compound.

Glazing Intermediate and Large Lights — Glazing Methods

For panel sizes up to 96" x 144", use continuous wood bead, metal stop, or channel glazing - not points or clips. Use elastomeric sealing compounds, vulcanized butyl tape, or dry caskets as sealants.They work because they allow large panels' expansion and contraction without breaking weather seals. Don't use ordinary glazing compound.

Be sure gunned-in sealing beads are at least ¼" wide by ¼" deep. Set the ¼" sealant bead by inserting a ¼" continuous non-oily filler tape into the sash. If there's any question about a material's compatibility with ACRYLITE® extruded (FF) sheet, contact Roehm America LLC.

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