French Doors – How to Install New French Doors
Prehung door systems are door panels assembled to a manufacturers frame and is designed exclusively for that door panel. Many contractors are still under the belief that because a unit is prehung it can be placed into any opening and immediately fastened to the building. All units must be level plumb and square. This can only be established by the following installation guide lines and missing one step will cause incorrect operation as intended by the manufacturer.
As a prior warranty rep inspecting doors installations throughout the tri-state area, I have found that 8 out of 10 installed units failed as a result of installation. Poor performance, damaged parts from incorrect install techniques, out of level units, arc thresholds, binding panels you name it. Follow the steps below or make sure the installer follows to provide a proper installation. The old unit is now removed
Check left and right rough carpentry for left and right level (rack) and from front to rear level (street to yard direction) this will provide you with upfront knowledge as to how or where you may need to position the new unit. If you know what framing conditions exist before the door is set for install you will realize where potential mis-alignment with walls comes from.
Place a level on the entry floor threshold to determine where the unit frame may have to be raised or leveled. This is the biggest area of concern when installing, if you place the unit on an out of level base the remaining steps ill not provide proper operation. The job will be shot. Very rarely is a threshold 100% level as this is rough carpentry.
Before setting the unit make sure there is proper flashing which is a continuous metal wrap from under the door to “L” bend down in front which will be hidden behind the kick plate below the new unit threshold. Once installed provide 100% silicone to the top to insure new unit is placed in a full seal to prevent weather and wind from blowing under the door frame.
Place the unit and provide left and right wood block shims at the top head jam locations to temporarily wedge and hold the unit in place.
begin to level the unit, check the threshold and add shimming where necessary, under vertical jam stock only, to raise that part of the unit only to provide level set.
- Using your level place on interior or exterior of jam at left and right side (street to interior of home) to adjust to plumb and level.
- Using your level place on the jam frame left and right side (in line with the wall) to determine if the unit is level.
This is where a racked unit can fail. A racked unit is simply leaning to the left or right of plumb. If you have ever seen a door that rubs at the top frame or one part of the strike jam hits the door panel when closing or even the sweep is being pinched too tight when closing, then this may be caused by a racked unit. Check other doors throughout your home.
Once plumb level and square properly shim the frame where the manufacturer specifies. This is important as incorrect shimming will void warranties. Typically shimming locations are 3 area left side 3 area right. Hinge side is directly behind each hing which will align and close gaps where the door slab closes. Make sure these reveals left, right, and top are uniform and consistent. Over shimming will cause panel hit or binding, under shimming will cause improper operation, air leakage, system failure with component damage. Please read manufacturers direction in full.
Install set screws provided by manufacturer in the manner described by the manufacturer. Only set the unit as described by it’s manufacturer. There is a reason for this. There are expansion and contraction rules at play here. Also warranties may be void if the unit is not properly secured. Never install a door unit by the exterior brick mold trim only. I have personally failed hundreds of installs regarding this poor method. The unit frame will eventually separate causing fail and leaning frames.
Insulate the left, right and top head jam locations (not spray foam) using fiberglass insulation. Spray foam expansion may over pack the void between the newly installed jam and dwelling framing.
Install casing trim to interior along with door knob hardware and your basically finished.
Special notes: each step of the way test drive the unit by gently opening and closing the door, this will provide you with the knowledge as to where you may have a problem. Visit us for more information at www.compareglazingprices.co.uk/upvc-sliding-french-doors-cost