Door Threshold / September 12, 2018 / Ambra Daoust.
5. TOP HUNG OR BOTTOM ROLLING Some bifold doors are hung from the top to allow for a minimal threshold at floor level but with all the weight of the door being supported from the top a substantial upgrade of the lintel is normally required for strength and stability. Bottom rolling folding doors are a cost effective and popular alternative since the weight of the door is carried at ground level rather than suspended from the lintel. Whether you decide on an aluminium upvc or hardwood bifold door it is a major purchase for your project and one that should be carefully considered to ensure the very best value for your money.
With the rough opening clean and prepped for the new door and jamb move the system into place as one with door hung on hinges. Temporarily shim the side jambs tight top and bottom ends in the rough opening. Temporary shims at the bottom hinge may also be required to straighten door sag. The top hinge will sag just be aware that you will compensate for it later with shims and a screw to snug it when the door is installed permanently. Use of a level isnt necessary just align the jambs flush with the interior plaster and shift shims to square the door in the jambs with even spacing reveal.
Several sill manufacturers provide plastic threshold protection that is specific to the model of sill they are selling. Unfortunately heavy duty plastic protectors are not available for every type of entry threshold so the protection is not easy to obtain. There is one surface protection company on the west coast that does inventory plastic threshold protection for two of the most common sill profiles. For protecting sliding door tracks there are two types of threshold protection. The first is a hinged plastic protection that flips over the tracks of sliding doors to keep them clean from debris.
Tightly wedged shims will allow you to operate the door carefully. Open and close to check the door touching the weather stripping evenly top to bottom for any possible jambs twist. Adjust as necessary even though jambs may not flush with plaster top to bottom. A good carpenter wont assume the original door was installed correctly right? Check the brickmold reveal you should have consistent and even measurements side to side and top to bottom. Its unusual to have brick out of plumb to any great extent. Adjust shims again as necessary. Index the jambs in the rough opening and the shims to jambs with pencil for reference when installing the system permanently. Remember you only have one chance to get this installation right so be patient - you will be rewarded with a satisfying outcome.