How To Seal Windows From Draughts


Draught proofing strips will solve most draught problems with opening casement windows and often with doors, too (sash windows need slightly more treatment — see below). But how long your draughtproofing will last depends on the quality of the materials you use. At the cheapest end of the scale are proprietary draught proofing strips of self adhesive foam plastic. Don’t be too cost conscious when buying this, the cheaper foam tends to rot quite quickly, and it’s best to buy one with a liner or coating which prevents it stretching as it’s being applied.

How To Seal Windows From DraughtsThis foam can be fitted at the contact points of a window so that when the window is closed, the foam is compressed to form a draught excluding seal.

Make sure that the area the foam is being attached to is thoroughly clean — if it’s not, the foam won’t stick properly.

Cut a length of strip to the exact length required, and offer it up to the window to check it’s been correctly cut.

1. Peel back about 50mm of the back tape and push the sticky side of the strip into place. Work down — or across — the window frame securing the strip and pulling off the backing tape as you go.

2. Use your thumb to compress the foam down its length to ensure that the strip hasn’t lifted at any point, then pull off the liner.

Even the best foam hasn’t got an extensive life, and another alternative which is probably better suited to warped timber or rusted steel frames is one of the silicone sealants often sold for sealing baths.

3.Open the windows and apply a thin bead of sealant from the applicator nozzle on the tube, all along the contact points on the frame. This will take up any irregularities between the window and frame and can, if needed, be easily removed. The material takes up to 24 hours to dry fully, but in most cases windows can be closed after an hour or so.

TIP: Always apply strip or silicone sealants on a warm dry day. This reduces the risk of trapping moisture and causing rot or rust as a result.

For a longer term solution to window draughts, you can use rigid weatherstripping made of polypropylene, vinyl, phosphorbronze or aluminium. These strips have a slight inbuilt springiness which forces them outwards against the frame.

Cut the strip to length and offer it up to the frame to check it is a snug fit top and bottom or widthways.

Tack the strip to the frame using either galvanized pins or tacks.

There are usually holes prepunched at regular intervals. Always tack from the top down and at regular intervals. Excessive space between tacks might cause the strip to ripple and reduce the draught proofing effect.

Although it’s fairly easy to draught proof the top and bottom of a sash window — you can use foam strip for this —dealing with the sides and middle can be a problem. The sliding action of the window tends to rub against most types of excluders.

The one type of excluder which works well, particularly at the sides of the window is a sprung metal or plastic weather stripping. To fit it, you need to remove the staff beading and parting beading which hold the sashes in place from the inside of the frame.

4. To do this, ease a screwdriver tip under the staff beading and gently knock it with a hammer. This will loosen the nails holding the beading in place and you should be able to prise it off. The parting beading is usually fitted into a slot in the frame but can be removed in the same way. If the beading is damaged, you can take this opportunity to replace it with new beading which can usually be bought from most timber yards.

5. Once the beading has been removed, fit the strip inside the frame on the pulley stiles.

6. In the middle, nail the strip inside the gap to the rail of one of the sashes. Make sure you fit it the right way up so it doesn’t get caught up when you slide the sashes.

If only the gap in the middle is causing problems, you can fill this with selfadhesive nylon pile which should be fitted to the rail of either sash. This is a lot easier to apply, as you don’t have to dismantle the window.

Another simple way to seal sash windows is to fix flexible strips to beads around the frame, both inside and out. This is simple and cheap and doesn’t require you to remove and replace the staff beading.

Leave a Comment