Problems with Slim Double Glazing
Firstly these slim double glazing did not conform to all parts of building regulations. They failed on two major areas:
- Testing to EN 1279 part 2 – Long term test method and requirements for moisture penetration
- Testing to EN 1279 part 3 – Long term test method and requirement for gas leakage rate and for gas concentration tolerances
These windows were also manufactured with a typical 3mm thick spacer bar which could not pass the required sealant depth of over 5mm or more. The overall sightlines of double glazed windows are normally between 8 to 10mm, while the slim double glazing was often reduced by a further 2mm to only achieve a 5mm sightline.
By reducing the sightlines to only 5mm would reduce the visibility of the spacer bar, therefore providing a single glazed appearance. However, by reducing this sealant depth had a significant effect on resisting moisture penetration and gas loss, which results in failure of double glazing. This is why on near enough every glazing unit in this household there was bad moisture and condensation build up.
Slim Double Glazing Manufacturer Guarantees
Most good double glazing companies will offer a 10 year guarantee on their double glazed windows. This cannot be achieved with slim double glazing as there are too many problems that will occur down the supply chain.
- Guarantees will be offered however the double glazing company will not inform the client that the glazed units must be to at least 8-10mm sightlines. While the pass through glazing bars must exceed 20-22mm across.
- Many manufacturers will state that these slim double glazing units have conformed to Part 2 and Part 3 of EN 1279. However, what they fail to inform the client is that these tests were tested by standard double glazing units with normal sightlines and without narrowed cavities.
As these slim double glazing units have so many underlining and potential issues, this causes further issues in the breakdown in service. As these windows are not manufactured to the correct specifications required to building regulations, causes a substantial decrease in the life of these windows. This is more evident with the increased rate of gas dissipation in the captivity causes condensation within the window.
Replacement Double Glazing
Peterborough Doors and Windows are notorious for our exceptional work and quality of our double glazing. We were asked to replace this existing slim double glazing with our high quality A-rated double glazed units. The homeowner was experiencing really bad condensation and moisture build up between the double glazing. The windows were also extremely draughty.
Reasons why windows become draughty
The Window Hinges
One of the main reasons why draughts will enter through the window is due to broken window hinges. Over a period of time with a build-up of dirt, dust, rust also wear and tear, this will cause the window to incorrectly shut, resulting in the hinges will become out of line. Eventually the window (sash) will not closing tightly against the inner window seal. Gaps will then appear causing unwanted draughts.
We advise the occupier to open and close the window a few times whilst observing if the sash touches the seal when the window is fully closed. Then push your fingers against the sash over the corner areas where the hinges are located. Then open and close the window whilst pushing on the sash. If the hinge is working correctly then the sash will be pulled in tight even when you are push against it.
If a gap has appeared between the sash and the window seal then the window hinges may need replaced.
The next check will also be on the hinge side of the window frame, which is the middle of the sash. Most windows regardless of the manufacturer will have a set of interlocking plastic blocks located at the midpoint of the window opening. These blocks are typically triangular in shape, with one side will be screwed to the window frame while the other side screwed to the sash. When the window is closed, the block meets and pulls the sash tight into the window seal, within the middle of the window. These blocks are extremely important for larger windows as uPVC frames are flexible therefore without these blocks the uPVC sash could possibly leave a small gap. This will then causes draughts.
To test these interlocking window blocks, simply press against the sash on the middle side of the hinge side of the window. If the sash moves then these blocks need to be repositioned. If there is no movement then the blocks are working correctly.
The Window Lock
The next check will be to see how tight the window closes on the lock side. Most window manufacturers will use a multi-point locking mechanism which will lock the recessed into the sash. The window lock has a circular roller lock which will lock into a metal receiver located within the window frame. The circular roller can be easily adjusted to either tighten or loosen the window.
To test the window locks then simply observe the window whilst opening and closing the window handle a few times. The sash should press against the seal throughout its full length. The window locks can be easily adjusted to either tighten or loosen against the seal.
The Window Seal
On near enough ever window type there will be a seal that surrounds the inner part of the window frame and also around the sash. Make sure that the seal does fit all around the window. Ensuring that there is no damage.
On really old uPVC windows and also aluminium windows a seal gasket is inserted to hold the windows within their frames. These seals can shrink over time therefore leaving gaps between the sash and the frame. These seals will then need replaced.
How the Window Closes
If the sash is not correctly fitted and is squared within the window frame, then this could cause draughts. Check around the sash and frame ensuring that window closes correctly around the frame seal. Check each corner whilst the window is closed. The weld of the sash should line up correctly within the corner of the window frame. Ideally the sash should touch the seal when the window is fully closed.
Plastering & Window Boards
The last and final check is the plastering around the window and the window board. This should be checked on both the outside and inside of the window frame. A small gap within the plastering can easily result in draughts getting into the home. A small gap even from a meter box could quite easily travel along the wall cavity then through a window board. Fill in any gaps no matter how small within the internal plastering and window boards with filler or silicon. This will ensure draughts will not enter via the windows.
Why purchase A-Rated Double Glazed Windows
We often hear lots of technical terms relating to energy efficient windows, so how do we know which double glazed windows to invest in?
Firstly all energy efficient windows will be coded between A and G. A is obviously the most efficient whilst G is the least. Between each letter there is also a + and a – grade. The higher the grade then the more energy efficient therefore the less energy you will lose. A-rated windows will only let out the same amount of energy as it would to let in. A+ windows however will allow more heat to enter than which will escape.
Therefore the higher the rating then the less heat will escape your home, saving you money on your heating bills on the long term.
Benefits of A-rated energy efficient windows
Did you know that over 20% of heat could escape from your home via your windows? Could you image how much your old draughty windows could be adding to this heat loss? By replacement double glazing with our A-rated double glazed windows could fill your home with natural light. Whilst keeping your home nice and warm and secure.