Window Seal Replacement

Every opening uPVC window relies on rubbery strips around the sash and frame to close the gap when the window is shut. These gaskets stop draughts and rain getting past the opening edge, and a second set usually holds the glass in place against the frame. When they shrink, crack or come loose, you notice whistling in wind, cold spots near the window and sometimes water on the sill. Sean Cardwell Windows can replace window seals and gaskets on uPVC windows from our Weston-super-Mare base.

This page is about the seals on the frame and sash. Moisture trapped between two panes of glass is a different fault, caused by the sealed glass unit itself, and our misted double glazing guide covers that.

Signs a window seal is broken

Look along the edge of the sash with the window open. Healthy gaskets are flexible and sit snugly in their groove. A worn window seal may be flattened, brittle, cracked at the corners, shrunk back from the corners or hanging loose. Other signs include a draught you can feel with the back of your hand, rattling in strong wind, and water tracking inside after heavy rain. On the coast, salt and sun speed up the ageing of exposed seals.

Sometimes the seal is fine but the sash is not pressing against it, because a hinge has worn or the keeps need adjusting. That is why we check how the window closes before replacing anything.

What window gasket replacement involves

Window gasket replacement usually means pulling out the old strip and fitting a new one of the correct profile into the same groove. Gaskets come in many shapes, and a profile that is too thick can stop the window locking, while one that is too thin leaves a gap. We match the replacement to the window system as closely as possible. Glazing gaskets that hold the glass can also be renewed where they have shrunk, which may involve removing beads carefully so the unit is not disturbed.

Seal replacement or a new unit?

New seals cure draughts and leaks around the opening edge, but they will not clear fog inside the glass. If you can see moisture or a milky film between the panes, the sealed unit has failed and replacement glass units are the answer. Some windows have both problems at once, in which case the two jobs can be done together.

Window seal replacement across a whole house

Older uPVC installations often have seals of a similar age throughout, so when one window starts to draught the rest may not be far behind. Checking every window at the same visit and replacing the worst first is a practical way to spread the work. Bedrooms and rooms facing the prevailing wind usually show wear soonest.

Keeping new gaskets in good condition

Once fitted, gaskets last longer if they are kept clean. Wipe them with warm soapy water when you clean the frames, avoid solvent cleaners, and check they have not been pulled out of their groove when the window is shut. A little silicone-based care product made for rubber seals can help keep them supple.

Related faults

Seals are only one reason a window feels draughty or stiff. If the window binds or will not shut, our window won't open or close page walks through the usual causes, and uPVC window repairs covers hinges and handles. When you get in touch, a close photo of the old seal helps us identify the profile. Use the quote form to describe which windows are affected.