The J top mount heavy duty 4-door biparting bifold kit folds four panels accordion-style along a wall-mounted track, with two panels folding and stacking to each side of the opening — built for solid-wood panels, oversized doors, and installations where standard duty hardware isn't enough — with no hardware visible on either door face. The J top mount roller attaches to the top edge of each panel, leaving both door faces completely clear while the J-style roller arm remains visible above, maintaining the barn door aesthetic from the side.
This is a Goldberg Brothers heavy duty kit, made to order in Colorado with a limited lifetime warranty. Available in all 17 Goldberg Brothers powder coat finishes. Two 7 in pull handles are included — one per side. Ships in 10–15 business days. Total system weight capacity is 800 lbs across all four panels. For a fully clear opening, only 5 in of clear wall is needed on each side.
If the J-strap curve across the door face is part of your design intent, the J-strap heavy duty 4-door biparting kit is the right choice. For lighter or thinner panels within the standard duty range, standard duty 4-door biparting hardware is less expensive and fully sufficient. Biparting requires clearance on both sides of the opening — if clearance only exists on one side, see our 4-door one-way kits.
As described in our Privacy Policy, we collect personal information from your interactions with us and our website, including through cookies and similar technologies. We may also share this personal information with third parties, including advertising partners. We do this in order to show you ads on other websites that are more relevant to your interests and for other reasons outlined in our privacy policy.
Sharing of personal information for targeted advertising based on your interaction on different websites may be considered "sales", "sharing", or "targeted advertising" under certain U.S. state privacy laws. Depending on where you live, you may have the right to opt out of these activities. If you would like to exercise this opt-out right, please follow the instructions below.
If you visit our website with the Global Privacy Control opt-out preference signal enabled, depending on where you are, we will treat this as a request to opt-out of activity that may be considered a “sale” or “sharing” of personal information or other uses that may be considered targeted advertising for the device and browser you used to visit our website.