Questions and Answers for GRK Fasteners #8 x 1-1/2 in. Star Drive Trim Head Wood Deck Screw (600-Piece Per Pack)

A:  Hello, Lili. Thank you for reaching out to us. GRK Trim screws are designed to for wood-to-wood connections, and not to be used with cement or any type of masonry. Our sister company Tapcon has a variety of concrete screws, and you can reach either of us at 800-222-6990 with any application questions.

A:  Hi Thomas, you could use these to put together a plywood box. However, we recommend our R4 or RSS screws as they are structural code approved and offer more holding power. Please feel free to call us at (877) 489-2726 or email us at CS@itwbrands.com. There we will gather the necessary specs to recommend the product you will need.

A:  The GRK Fin/Trim screw can be used to in this application. Although, we would recommend using our Deck Elite screws that have been designed specifically for use in deck board applications.

A:  Hi Scott, Our #8 FIN/TRIM screw has a head OD of 0.197" for more information see the engineer drawing found here: https://www.grkfasteners.com/getattachment/cbe1684f-0b30-4486-93f8-84d28879311a/Sales-Support-TRIM-RT or reach out to our customer service team at at (877) 489-2726 or email us at CS@itwbrands.com

A:  Hi Bill, we recommend using the GRK RT Composite screws for any composite fastenings. The reverse thread on that product was designed to mitigate the material around the head dimpling. If you have additional questions please contact our customer service team at (877) 489-2726 or email us at CS@itwbrands.com.

A:  I have used these trim head screws in MDF and never needed to predrill nor countersink for the heads. There was no "bubble up" issue where the head penetrated the MDF to contend with either. Great holding strength too.

A:  YES, absolutely. Will countersink into hardwood as well.

A:  Yes, they are designed to countersink and do so easily.  

A:  They should. You can always use a countersink bit designed for that purpose. 

A:  I would think so, depending on wood thickness & material.

A:  Yes, would consider using wood glue on joists to fight against gravity teamed with the screws

A:  I had a different length of these and the size was T-10