Installing Door and Window Sashes

You’ll recall that the frames for the new windows and doors were installed earlier and that the sashes themselves were safely stored away to avoid the possibility of them being damaged while there was so much work going on. Now that the major works are finished these are to be fitted.

The French doors at the back of the house comprise a pair of glazed doors and a fixed glazed panel either side. This will give a great outlook onto the garden from the new room. The double glazed units for each of the side lights are fixed first. The rebates in the new frames are cleaned out first – whilst they are new frames, it’s important to make sure there is no debris such as splashes of mortar or grit that might damage the glass panels. The carpenter then runs a bead of glazing silicone around the rebate and sets a couple of glazing blocks at the bottom. These blocks are to hold the unit off the frame slightly. As the carpenter explains, a small gap around the glass unit is needed to allow for expansion and contraction. Otherwise, they could end up cracking when the weather is hot.

The double glazed unit, which is pretty heavy, is lifted into the opening and centralised before being gently squeezed back against the silicone. The idea is to create a full seal around the glass but not to squeeze the silicone out completely. Self adhesive cushioning strips are then applied to the perimeter of the glass before fixing the glazing beads against them. This provides further thermal expansion protection. The glazing beads were made with the custom frame and have been pre cut with mitres at the corners.

Next, the carpenter fits the doors. As you can see these still have horns on the ends of the frames. The stiles for the doors are left like this when they are made so as to protect the corners from damage. The first job is to trim them back. They are marked with a tri square and cut back flush with the top and bottom rails. The hinges are then set in the back edge of the door. The carpenter explains that three hinges will be used on each door as, once the glass is fitted, they will be fairly heavy and two hinges wouldn’t provide enough support. The doors would be liable to drop and eventually start binding along the bottom edge. Having marked and cut out the rebate for each hinge on the door, it is lifted into the frame and sat on small wedges at the bottom to provide the right amount of clearance. The position of the hinges is then marked off against the frame and the door removed. The rebates on the frame are cut out and pilot holes drilled for the screws. These are brass hinges so brass screws are used and these should always have pilot holes drilled first. Brass is quite a soft metal and can easily be damaged – pilot holes allow the screws to be fixed without too much pressure. The hinges are screwed to the door and the door lifted back into position so that they can be fixed to the frame. Having checked that they open and close freely, the lock can now be fitted.

The leading edges of the doors are rebated and a similarly shaped sash lock is needed to suit this. The carpenter marks out the position of the lock and the mortise required. The recess for the face edge of the lock is cut out with a chisel. He then drills out the bulk of the mortise to the correct depth before trimming and cleaning the slot with a chisel.

The corresponding recess for the lock plate on the other door is cut out and the holes for mounting the handles are drilled. The lock and strike plate are mounted and fixed in position, then the spindle for the handles fitted through before finally fixing the handles in place.

Added security is provided by installing rack bolts in the top and bottom of the door. A hole is drilled centrally into the edge of each rail to the required depth and the outline of the face plate marked. A shallow recess for this is then cut out with a chisel so that the bolt sits flush in the rail. The bolt is held against the face of the door so that the key hole can be marked and cut. With the bolt fixed in position, the door is then closed and the key used to wind the bolt out. As the carpenter shows me, the end of the bolt has a small point on it which creates a light indent in the frame where it touches. This is then used to position, mark and make a cut out for the lock plate.

There are three new window frames – two on the side elevation of the house and one at the rear. The side windows are both sliding sashes but have modern spiral balances rather that the old fashioned sash weights on cords and pulleys. As with all custom joinery on the job, the units were made in a workshop off site so the sashes have been made to fit exactly with no trimming or planing required. The sashes themselves have been pre glazed with sealed double glazing units.

The first sash is held in position in the frame and the spiral balances inserted in the groove in the back edge of each side of the sash. These are then fixed to the frame top and bottom. Lifting the sash, the carpenter then fixes a special bracket to the bottom – the sides of this bracket sit either side of the sash balance. Checking that the sash raises and lowers freely it is then positioned part way up and propped in position. The spiral rod mechanism is then fed into the groove and adjusted by winding with a special key to create the correct tension. The end of the spiral balance is locked in position by lugs in the foot bracket. This certainly doesn’t look like the easiest of jobs but the carpenter soon has the sash fitted and balanced so that it slides freely but also stays put at whatever position it is left in. The process is repeated for the inner sash and then both sashes on the upstairs side window.

Brass window fitch fasteners are fitted to the sashes. Both parts of the fastener are positioned on the sash and the fixing points marked and pilot holes drilled for the brass screws. The retaining section of the fastener is positioned on the bottom rail of the outer sash and the thumb turn cup section positioned on the top rail of the inner sash. Once both have been screwed in place, the fastener is tested to ensure that it operates, correctly securing the two sashes so they cannot be opened and, to make sure that they fastener doesn’t foul anything as the sashes are moved up and down.

The final window to be completed is the one to the rear bedroom in the extension. This is a little different to the other two. It has a large central section and narrower lights on either side. Although you wouldn’t be able to tell from the outside, the side lights will actually be fixed sashes and only the central section will open. The sliding sash mechanism is of the old fashioned style and, because the inner mullions are fairly narrow, the weights have had to be mounted in the outer vertical sections. This makes for an interesting detail. Sash cords are fed from the top of each side of the central section, over a roller, across the top of the fixed section into another roller, then down in to the box section at the side. These are then tied to the square profile metal sash weights which are then positioned inside the boxed sides. With these in place, the sash cord is then pulled back up and fixed to the sides of the sashes. Balancing the sashes correctly takes a bit of practice and skill but the carpenter on this job makes light work of it. Repeating the process for the inner sash, the result is that the weight of each glazed sash is perfectly balanced by the metal weights and they slide easily as well as stay put in any position. The fixed sashes on either side are positioned in the frame and fixed in position.

As with the other sash windows, fitch fasteners are fixed between the bottom rail of the outer sash and the top rail of the inner sash so that they are secure.

If you live in the Hertfordshire area and are looking for a professional building contractor, you can get in touch with G L Smith and Sons via their website: http://www.glsmithandsons.co.uk/