CAVITY CLOSER

Cavity closer is an inner constituent part of a cavity wall that fits within its structure which is used for closing windows and door cavities to protect from damp, mould and heat loss that takes place around the openings. In other words, it is a barrier between the wall leaves, designed to stop water from infiltrating into a building. It also acts as an alternative to vertical damp proof course (DPC), ensuring compliance with building regulations. If a cavity closer used fire-resistant material, it would be considered a cavity barrier, even if that wasn’t their design purpose. Cavity closers are different from cavity barriers. Cavity barriers are mainly used to prevent the spread of fire unlike cavity closers – they are not used for preventing the spread of fires.

TYPES OF CAVITY CLOSERS

SINGLE FLANGE CAVITY CLOSERS

Made to fit into a rebated detail where the window frame is positioned behind the outer leaf. 

It helps prevent moisture, mould and staining from around windows and doors. This closure has a single flange, and is suitable for fitting to standard window cavities. Closer can be used to make sure all industry standards are met.

DOUBLE FLANGE CAVITY CLOSERS

Made for use in standard in-line cavity walls. 

It is also used in sill details by simply cutting a length to suit the width of the window and placing it in the cavity at the sill. A DPC is still recommended in horizontal applications. 

FIRE RATED CAVITY CLOSERS

Made to improve fire safety.

Fire rated cavity closers can prevent the spread of fire for 30 minutes or an hour, depending on the fire-rated product you choose. Fire-rated cavity closers can help to ensure your building is compliant with Building Regulations Part B (fire safety). Fire cavity closers can act as a way of slowing a fire moving through the cavity wall, offering extra time for occupants and firefighters.

INSULATED CAVITY CLOSERS

Made to reduce heat loss.

Insulated cavity closers also called thermal cavity closers are an effective way to eliminate cold bridging around doors and windows. By including cavity closers in your build, you’ll be providing increased insulation in the areas that need it most. Available with Grey or White EPS, PIR or Phenolic insulation core.

CAVITY CLOSER WIDTHS

There are different brands such as Kingspan, Cellecta, Eurocell or Xtratherm of cavity closers but all perform the same function. Cavity closers usually come in standard width of 100mm to work with all new cavities.
50mm | 65mm | 75mm | 85mm | 90mm | 100mm | 110mm | 125mm | 150mm

HOW TO FIX CAVITY CLOSER?

Classic closures, being so versatile, can be fixed to the window frame, installed during wall construction or retro-fitted after the wall construction is complete. Closures are easily cut using a fine tooth saw. Joining two pieces of closure is achieved with a minimal amount of waste. When installing cavity closers it is recommended to follow the manufacturer's installation instructions.

• Measure the distance between the brick and the block to get the width of the cavity. If this width is 50mm then you need a 50mm cavity closer. Do not cut the plastic outer shell!

• Cut the cavity closer to size. You can use either a jigsaw or handsaw. Cavity closer has pre groves so you just trim off the excess with a kraft knife. 

• Get rid of all unnecessary mortar from cavity space so closer could sit flush.
• You should do the bottom part of the window first, then the vertical closer should sit on top. When jointing horizontal to vertical, trim both PVC flanges and allow the vertical to extend below the horizontal - this stops water ingress.
• Cavity closer has usually a thick edge - you fit that to the outside.
• Secure the closer in position (into the cavity) by putting back edging first. Make sure there is a 50mm minimum overlap between the flange and the masonry skin.

• Put appropriate fixings after you installed cavity closers.

CAVITY CLOSER BUILDING REGULATIONS

Part C of Building Regulations require cavity closers surrounding both doors and window openings for the prevention of water penetration. The window frame requires a minimum set back of 30mm over the cavity, it will then need sealing around the frame.
The regulation in Part L of Building Regulation states that the cavity closers have a minimum thermal resistance path of 0.45m2k/W. The higher this number the less heat loss.
Part B of Building Regulation covers the requirements for Fire rated cavity closers. A fire rated cavity closer can prevent the spreading of fire for up to one hour. Insulated cavity closer without fire rating will not comply with regulations. Fire-rated cavity closers can prevent the spread of fire for up to 30 minutes or an hour, which can be crucial if a disaster does occur.

CAVITY CLOSER DETAIL

Cavity closers can be used in a range of different constructions, including masonry, timber frame and steel frame systems. Cavity closers come in a range of widths and specifications.This product is used to close cavities and is suited to all types of windows and doors and is available in sizes to fit cavity widths from 100mm, 150mm and 200mm.

CAVITY CLOSER NEAR ME

Cavity closers are popular due to the fact that they are readily available in well known stores near your location such as B&Q, Wickes, Selco, Screwfix or Travis Perkins. We also offer cheap deals and best prices, because products come to you directly from the manufacturer.

Related articles:

Cavity wall. All you need to know

All types of partial fill cavity insulation

Best 6 passive fire protection cavity barriers

4 types of full fill cavity insulation explained

Video credit: youtube.com/watch?v=6W6uj68sYCQ&t=7s