Schüco bifold doors installation: what actually happens on the day

A folding door installation is not a delicate operation. It involves a lot of weight, a certain amount of noise, and a period during the middle of day one when the back of your house is a hole. Knowing the running order in advance makes the whole thing much less stressful, and — more usefully — tells you when to look closely.

Before the van arrives

The final survey should already have happened, on site, with the structural opening complete and the beam in place. Doors made from a drawing rather than from the real opening are the single most common cause of a wasted delivery.

In the week beforehand, sort out: parking for a long-wheelbase van (in Southgate and Muswell Hill this genuinely needs planning, and a suspended bay costs less than a failed delivery); a clear route from the kerb to the opening at least a metre wide; the floor inside protected and the room emptied for two metres back; and any garden furniture, pots and washing lines moved well clear.

Day one, morning: strip out

The old frame comes out first. If it is a timber or uPVC patio door, expect it to be cut out rather than lifted out — a reciprocating saw through the jambs, then the sections levered free. It is loud and it produces a surprising amount of debris. This is the point at which homeowners tend to panic slightly. It is normal.

The opening is then squared up and checked. A good fitter measures the opening in three places for width and three for height before anything goes in, and checks the head for level and the reveals for plumb. If the opening is out, this is when they will tell you — and when a decision gets made about packing versus cutting back.

Setting the cill

The cill or threshold goes down first, bedded on a continuous bed of sealant, levelled along its whole length rather than just at the ends. This is the most important twenty minutes of the entire job.

A cill that is level along its length but has a dip in the middle will hold water and, worse, will throw every leaf above it out of alignment. On a five-metre run, a two-millimetre dip is enough to make the middle leaves bind in summer. Watch this stage. A long level or a laser should be in use, not eyesight.

The frame

Jambs and head next, squared, packed and fixed. Two things to look for: the packers should be at the fixing points, so the frame is not being pulled into a bow when the fixings are tightened; and there should be a consistent gap around the frame for sealant, not a frame rammed hard against masonry on one side and floating on the other.

Fixings go through the frame into the structure at intervals specified by the system. Diagonals get measured. The frame should be square to within a couple of millimetres before anything is hung on it.

Hanging the leaves

The leaves arrive as complete panels, usually unglazed on larger sets and pre-glazed on smaller ones. They are hung onto the top track and lower guides, and the fold sequence is set. At this point the doors will move but will not be right — gaps will look uneven, the leading edge may not meet the jamb cleanly. That is expected. Adjustment comes later.

Glazing

If the units go in on site, this is a two- or three-person job with suction lifters. Each unit is set on packers inside the sash — and the packing pattern is not arbitrary. Toe-and-heel packing is what stops a door leaf dropping out of square over time by using the glass itself as a stiffening diagonal. Badly packed glazing is the reason a door that was perfect in January is catching in June.

Beads go on, gaskets are rolled in, and the leaves suddenly feel completely different: much heavier and much more solid. This is when you see how the doors are going to look. It is generally the good bit of the two days.

Day two: adjustment and weathering

Now the fitters earn their money. Hinges and rollers on Schüco bifold doors are adjustable in more than one plane, and a full set has a lot of adjustment points that all interact. Getting even shadow gaps down the full run, consistent compression on every gasket, and a fold sequence that runs without a shove takes time. An hour of fiddling at this stage is a good sign.

Then the perimeter is sealed — externally with a low-modulus silicone over a backer rod where the joint is wide, internally to suit the finish. Drainage slots in the cill are checked clear. Locks and keeps are aligned so the handle throws without force.

The snagging checklist

Before you pay the balance, go through this with the fitter present:

• Every leaf opens and folds with one hand, no shoving
• Shadow gaps between leaves are even, top to bottom, on every joint
• The traffic door closes and locks without lifting or pulling
• Handle throws smoothly with the door merely pushed to, not held
• Gaskets are continuous, seated in their grooves, not stretched or missing at corners
• Drainage slots in the threshold are open — pour a jug of water on the outside and watch where it goes
• External seal is continuous and neatly tooled, with no gaps at the cill ends
• No scratches on the coating, particularly at handle height and along the threshold
• Glass is free of edge chips and the units are correctly oriented, coated face inward
• All protective film removed and all keys, handles and paperwork handed over

The first fortnight

Silicone takes a few days to fully cure. Doors bed in slightly. It is completely normal for a set to need a small adjustment two to six weeks after fitting, and any decent installer builds a return visit into the price — ask whether yours does before you sign.

What is not normal: water inside after rain, a leaf that drops noticeably within weeks, or a handle that needs force. Report those immediately and in writing rather than waiting to see if they settle. They do not settle.

Common questions