For maximum frame & fastener life use redwood, cedar or cypress. Avoid sap wood.
Seal high moisture areas of frame with satin marine spar varnish or Varathane. This protects top & bottom plate, and areas where polycarbonate contacts wood. This decreases wood rot, stops wood discoloration and creates a barrier between the chemicals in pressure treated and the polycarbonate. The smooth, nonporous surface is ideal for placement of a thin coat of ArmorAll, place on areas of frame that come in contact with poly, just prior to installation of the sheet. ArmorAll assists in free expansion & contraction of the poly, decreasing possible movement noise. For poly sheets 10’ or over don't use ArmorAll. Use a polycarbonate compatible foam tape. When an order of poly 10’ or over is placed online you are sent to a page that explains the use of foam tape and provides a link to a form that calculates tape needs and accepts online orders of this special foam tape.
18.8 - 300 Series Stainless Steel Screws used with ACQ Treated Lumber. Other screws will corrode
Our standard screws are hardened carbon steel with a special Organic Polymer Coating. This screw is appropriate for all species of wood. The ACQ chemical will corrode the screw, so we do not recommend using ACQ if possible.
We do have an option for fastening polycarbonate to ACQ pressure treated, should you need to.
The option is separate, unpainted, 18.8 stainless steel screws and separate washers. These screws are softer and one has to set carefully or the screw will snap. Cost is about twice the cost of of our standard steel screw assemblies, and are sold in the same 250 bag qualtity.
Simple solution is avoid ACQ. If this is not an option, place your order online and select Frame Type - Pr. Treated. A dialog box will appear instructing you how to select the 18.8 stainless steel screws and separate washers.