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Timber Window Glossary

Antique Glass – Generally refers to the process of flat glass production using the traditional mouth-blown method. The sheets produced are of modest size but are large enough for most restoration works.

Casement Window – Generic name for a window that has openers which are hung on hinges, at the side – usually metal or timber frames.

Cathedral or Rolled Glass – “Cathedral” is a rolled glass and started to be commercially available in 1830’s. Produced by pouring molten glass onto a metal or graphite table and immediately rolling it into a sheet using a large metal cylinder. The rolling can be done by hand or machine and can produce a very wide variety of colours and surface textures including hammered, rippled, seedy, and marine textures.

Chamfered – The edges have been removed lengthwise at an angle.

Crown Glass – Crown glass was an early type of window glass and relatively primitive. It was formed by twirling a sphere of molten glass into a disc. At the centre of the crown glass, a thick remnant of the original blown glass would remain, hence the name “bullseye.” First made in 1674, and until 1830’s.

Dovetail – A type of joint. One piece has a splayed shape – like a dove’s tail – and fits into the socket or eye of the second piece.

Doweling – Cylindrical piece or length of wood. Also known as rounded wood.


Drip groove – A groove cut or moulded in the underside of a door or window sill to prevent rainwater running back to the wall.

End grain – The exposed face of timber produced when it’s cut through a plane that’s perpendicular to the grain.


End-jointed – See glossary entry fan-jointed.


Engineered woodLayers of hardwood compressed together, as with our excellent Engineered Redwood timber option.

Fanlights – A fanlight is a window with glazing bars that is placed over another window or doorway, that opens like a fan, and is sometimes hinged to a transom.

Fascia board – A strip of wood that covers the ends of rafters and to which external guttering is fixed.


Finger-jointed – Also called end-jointed. Shorter pieces of wood are joined to create a longer piece of wood. The joint looks like interlaced fingers.


Fixed – Whether describing a door or a window, then the word fixed refers to it being non operable.

Float Glass – A modern & standard technique since 1959, molten glass is poured onto molten tin to create an even, smooth and uniform finish.

Glazing Bars (also called Georgian Bars or Astragal) – Originally glazing bars of both sash and casement windows were abundant and thick. On the inside they were moulded to refract light and reduce glare. On the outside they were rebated to hold a glass pane (with traditional wooden or metal frames).

Hardwood – Timber produced from broad-leaved trees.


Head – The top horizontal member of a wooden frame.


Head plate – The top horizontal member of a stud partition.

Horns – Small spurs of timber that project on a Sash Window – hanging down from the top sash and up from the bottom sash in some instances). Horns were introduced in the 19th Century to strengthen the joints.

Jamb – The vertical side member of a door or window frame.

Muff, Cylinder or Broad Glass – Preceded Crown glass and was made by blowing a cylinder of molten glass, which was then cut along its side and flattened in a furnace, leading to seeds and bubbles.

Mullion – Vertical bar or pier made of masonry or timber that separate opening casements and/or “fixed” lights to cater for larger windows.

Ovolo – Is a rounded convex moulding

Preservative treatment – The treatment of timber with chemicals to improve its resistance to attack by biological organisms, such as fungi, insects and marine borers. The chemicals can be brushed or sprayed onto the surface of the timber but treatment is more effective if the chemicals are impregnated into the timber under vacuum and/or pressure in special treatment vessels.

Rebate – A rectangular recess along the edge of a timber [frame] designed to receive a shutter, door or window.

Reveal – The vertical side of an opening in a wall.

Sanded – Smooth surfaced – smoother than a planed surface.

Shake – Wood that’s split to reveal its natural texture.


Shingle – Wood sawn lengthwise that’s thicker at one end – the butt – and thinner at the other end – the tip.


Short grain – When the general direction of wood fibres lies across a narrow section of timber.


Sill – The lowest horizontal member of a stud partition or the lowest horizontal member of a door or window frame.


Soffit – The underside of a part of a building such as the eaves or archway.


SoftwoodThis is usually obtained from pine, fir, spruce or larch. Most structural timber used in the UK is softwood.


Staff bead – The innermost strip of timber holding a sliding sash in a window frame.


Stile – A vertical side member of a door or window sash.


Stopper – A wood filler which matches the colour of the timber.


Strength grade – The strength of timber varies with the species and is also affected by characteristics like knots, slope of grain and splits. Each piece of timber used structurally has to be strength graded, either by visual inspection or by machine. The timber is marked with its grade and other information such as its species, whether the timber was graded wet or dry, the company responsible for the grading and the certification body responsible for overseeing the grading operation.


Sap – Liquid – mostly water – contained within cells in a tree or timber. Sap is the means by which dissolved food and salts are moved around the tree.

Sash – In the first sash windows produced the top sash was fixed and the bottom sash slid upwards in a groove, held open in position by means of pegs or metal catches. In the late 17th Century a variant was introduced as we are familiar with today – the ‘double hung’ sliding sash window, with both upper and lower sashes hung on cords and counter-balanced by hidden weight.

Stained Glass – Traditionally this is glass that has had a stain applied to the surface and permanently fused with the glass by firing in a kiln. Panels constructed in the same way as traditional leaded lights.

Stay – A horizontal length of metal bar affixed to an opening casement and that attaches to the window frame to hold open.

Transom – A horizontal bar dividing a window into two or more “lights”.

Toplight – A window above another window or door (see glossary entry fanlight)

U -Value – The u-value is a measure of how easily heat can pass through the materials that make the door or window

Timber Windows

What is Low-E Glass?

Ordinarily, glass will allow solar energy to pass from one side of the Timber window to the other.  This includes the relatively narrow spectrum of visible wavelengths, as well as those higher and lower wavelengths (known respectively as infra-red and ultra-violet light).

This is bad news!

Ultraviolet light has a habit of bleaching materials it comes into contact with.  Fabrics and wallpaper will fade much more quickly if they’re exposed to UV for a significant period of the day.

Infra-red light poses a different problem, in that it’s transmitted into the building as heat.  If you’re looking to keep cool during a blisteringly hot summer’s day, you’re going to struggle – you might even be tempted to draw the curtains in order to keep the sunlight out.

The Low-E glass in our Timber Windows comes with a special coating that’s designed to act as a filter, allowing visible light through while excluding the superfluous wavelengths to either side.  This will allow your interior to enjoy the benefits of more light, without the downsides posed by ultraviolet and infra-red.

How low-E Glass Works

When heat or light strike a surface, that surface will absorb a portion of that energy and re-radiate it.  How large a portion this might be will depend on the surface in question.  If you’ve sat in a car with black leather seats on a summer’s day, you’ll know that dark materials tend to absorb and radiate more energy than reflective ones.

The amount of energy radiated by a surface is known as its emissivity. Glass, unfortunately, is naturally high in emissivity.  The more we can reduce this, the better an insulator our glass will be.

On the surface of each pane of low-E glass is a microscopically-thin coating that is designed to reflect infra-red rays.  This coating can be made from silver, or a variety of other metals, but their purpose is always the same: to deflect heat away from the glass.

Types of Low-E Glass

Low-E glass comes in two different varieties, and it’s produced using two different techniques.

A passive Low-E coating is built to contribute to the amount of heat within a home, preventing energy from leaving and thus lowering the heating bill.

A solar-control low-E coating works in the opposite way. It reduces the amount of energy entering the home, helping to keep it cool.

The right type of low-E glass for you will depend on the location of the building.

How is Low-E Glass Coated?

Each type of glass can be coated using one of two methods:

Pyrolytic

This process emerged in the 1970s.  It is applied to the glass shortly after production.  The coating fuses neatly with the hot glass before the latter has a chance to set, and stays that way for the entire lifespan of the window.  The glass is then cut to size and shipped.

Magnetron Sputter Vacuum Deposition (MSVD)

This process came a little bit later, in the 1980s.  It’s slightly different in that it’s applied to the sheets of glass after they’ve been cut to size, using a vacuum chamber and magnets to apply the coating at room temperature.

For many years, passive coatings were produced using the pyrolytic method, and solar-control coatings using the MSVD method.  More recently this line has begun to blur.

What does Low-E Glass Look Like?

So what effect, if any, does a low-emissivity coating have on the appearance of the window?  Since there are many different types of low-E coatings, and they can be applied at different thicknesses, it’s easy to be misled by reports of a set of ‘tinted’ low-E windows which block out certain colours, and distort the view of the exterior.

If, however, you want to ensure you don’t get any nasty surprises, it’s worth inspecting the sort of low-E glass you’re considering before making your purchase.

How Much UV Does Low-E Glass Block?

The thermal performance of windows is typically measured using the U-value.  This number refers to the amount of heat loss the glass permits per a given area.  According to the U-value, low-emissivity windows tend to be twice as efficient as their plain-glass counterparts – but it’s important that an impartial initiative backs up the manufacturer’s claims.

Naturally, this figure doesn’t cover the UV light that low-E glass will block.  Depending on the strength of the coating, low-E glass can prevent anywhere between 80% and 99% of ultraviolet light from entering the home (compared with around 60% by a standard window).  This extra protection is especially worthwhile if the sunlight entering a window is immediately falling on a set of curtains, a fabric-covered sofa, or a prized rug.

Contact us for a quote – Timber Windows Direct.

What U-Value Should your Timber Windows Have?

When you are looking for a new set of Timber windows, there’s one metric that you’re almost certain to encounter, the ‘U’ value. This number is a way of describing a window’s thermal efficiency, but what does it mean? What is the best U-value Timber window, and what is the U-value of double glazing?

How Does U-Value Work?

Let us start with some definitions.

A U-value is a measure of heat energy moved through a given area of material in a given period of time. This might be a Timber window, but it might equally be a wall or a door. It’s most often measured in watts per metres squared, when the difference in temperature between the two sides is one-degree Kelvin. Given that that’s a bit of a mouthful, we tend to say ‘W/m2K’ instead.

It’s important to note here that the U-value of a given window refers to its efficiency per square metre. So, two windows might have the same U-Value, but transmit heat at different rates because one is a different size to the other.

The lower its U-value, the better an insulator the window will be. If you’re aiming for the most thermally efficient house possible (as most of us are, cost permitting), you should almost always go for the Timber window of the lowest U-value.

How to Calculate the U-Value of a Window

If you’re buying a new Timber window, you’ll be able to see its U-value advertised by the manufacturer. Unfortunately, calculating a window’s U-value yourself isn’t particularly easy, nor are your calculations likely to be totally accurate.

For example, not every glass panel is manufactured to the exact same standards, and what stacks up in a laboratory might not translate into the real world. While there are bodies like the BFRC (which we’ll discuss in a minute) there to maintain quality standards, it’s important to treat claims about efficiency with a degree of scepticism.

Secondly, the glass panel isn’t the only thing you need to consider – the window frame also conducts heat, and will contribute to the thermal efficiency of the window. While it’s possible to account for this in your calculation, given that the interior of a window frame is made from a range of different materials, doing so can be very difficult.

To comply with building regulations, windows (like every other element of your property) must meet a certain minimum U-value. In the case of a window, it’s 1.6 W/m2K. Double-glazed windows, filled with argon, are typically 1.4 W/m2K, while thicker triple-glazed windows can go as low as 0.7 W/m2K.

The British Fenestration Rating Council provide a colour-coded rating system to help homeowners distinguish between different qualities of window. Good windows which keep the heat in are rated A or above. Bad ones are rated E or below. While this rating system is easy to follow, and will prevent buyers from making a mistake they will regret for years, it isn’t quite as specific as the U-value. As such, when you are looking for windows, we’d suggest looking for the U-value and spending your money accordingly. Obtaining a quote for windows with a good u value is easy.

Ultimately you will need to look beyond the lettered rating, and look at the U-value.

Timber Windows

The Painting Process of Timber Windows

Timber Windows are preserved, painted and finished in 5 stages:

Stage 1) The first Chemical preservation stage is completed by direct dipping of the timber window into the preservative solution to protect against moisture absorption.

Stage 2) The second Chemical preservation stage is completed by direct dipping of the timber window into the preservative solution to protect against fungi, pests and mould.

Stage 3) Primer and Undercoats are applied.

Stage 4) First top Coat is machine sprayed to frame.

Stage 5) Top Coat is machine sprayed onto the frame. 

 

The process of “Dipping”

Dipping

The Dipping process consists of simply immersing the wood in a bath of creosote or other preservative for a few seconds or minutes. Similar penetrations to that of brushing and spraying processes are achieved. It has the advantage of minimizing hand labour. It requires more equipment and larger quantities of preservative and is not adequate for treating small lots of timber. Usually the dipping process is useful in the treatment of window sashes and doors. Treatment with copper salt preservatives is no longer allowed with this method.

Timber Windows

Timber Windows

 

Our Colour Palette

Here at Timber Windows Direct we use the Classic RAL colour chart.

RAL is the most popular Central European Colour Standard used today, The colours are standard for use in architecture, construction, industry and road safety.

RAL is a colour matching system used in Europe that is created and administrated by the German RAL gGmbH[1] (RAL non-profit LLC), which is a subsidiary of the German RAL Institute. In colloquial speech RAL refers to the RAL Classic system, mainly used for varnish and powder coating but nowadays there are reference panels for plastics as well. Approved RAL products are provided with a hologram as of early 2013 to make unauthorised versions difficult to produce. Imitations may show different hue and colour when observed under various light sources.

Why not obtain a quote for timber windows in a RAL colour?

 

Timber Windows

Timber Windows – Fire escape measurements.

What are the requirements for my Timber Windows to be fire escapes?

Timber Windows

 

General criteria for egress Timber Windows:

• Width and Height of Timber Window – Either of these are not to be any less than 450mm
• A Clear Openable Area – No less than 0.33m²
• Sill height – The bottom of the openable area should be no more than 1100mm above the floor area.
Only one window per room is Generally required, but you should refer to the approved document B to ensure you are compliant with building regulations.

Here at Timber Windows Direct we have made this simple for you.

The Minimum width and height for our sash windows to obtain a clear openable area of 0.33m2 are as follows}

Timber Sash window on Weights will need to be 650mmW x 1250mmH or greater.
Timber Sash window on Springs will need to be 580mmW x 1215mmH or greater.

IMPORTANT: IT IS NOT ENOUGH TO HAVE A WINDOW WITH DIMENTIONS OF 450mm X 450mm AS THE CLEAR OPENABLE AREA MUST BE NO LESS THAN 0.33SQM

Why not request a quote for Timber Sash windows at http://www.timberwindows-direct.co.uk

Timber Windows

Timber Windows and FENSA Certificates

Timber Windows and FENSA Certificates.

When do you need a FENSA certificate?

We often get asked by our customers if we can supply a FENSA certificate when supplying Timber Windows.

There seems to be some confusion over what FENSA actually is, plus how it is relevant to works being carried out in your home.

Even with a cursory glance at the FENSA website, It states that, FENSA is a government authorised Competent Persons Scheme for the replacement of windows and doors in England and Wales.

I will clear up any confusion…….. Enabling those purchasing Timber Windows to understand when a FENSA certificate is required.

What FENSA actually is?

FENSA stands for, The ‘Fenestration Self-Assessment scheme’ which has been set up by the Glass and Glazing Federation (GGF). As a means to self-certify compliance under Building Regulations, without the need for a separate assessment from Building Control.

If your installer is not registered with FENSA. All works that include replacing windows and doors will require you to get a certificate from Local Authority Building Control instead.

When does FENSA apply to your Timber Windows?

FENSA does not apply to conservatories, porches, commercial premises, new build properties or extensions.

In all of these instances you are required to go through the Local Authority Building Control process.

So, in summary ……….

If the Timber window or door is a new addition to your property, or the building itself forms part of an extension, or is a complete new build, then FENSA does not apply and you will require approval from Building Control.

If you are replacing an existing window, you can use a FENSA approved installer or alternatively apply for full Local Authority Building Control approval.

Please note that the homeowner is ultimately responsible for ensuring that their window or door installation complies with these standards and regulations.

Visit Toughened safety glazing – Building Regulations for information regarding building regulations.

 

Low profile trickle vents on Timber Sash Windows

Trickle Vent or no Trickle Vent?

Do we add a Trickle Vent that is the question?

The use of a Trickle Vent is often pondered over for a considerable period of time. Some people consider them an addition to a window that is not astetically pleasing but it may be essential!

Here at Timber Windows Direct we manufacture our windows with the lowest profile vents possible to minimise the look of the trickle vent. They are finished flush with the window as opposed to competitor versions which stick out as a whole unit.

The trickle does have a very practical reasoning behind though and this article in the Telegraph sums that reasoning up nicely…

Ventilation

Windows and doors provide ventilation to rooms within a dwelling and rules apply to how much ventilation is needed. The type and extent of ventilation will be dependent on the use and size of the room.

For example, rooms where steam will be produced (kitchens, bathrooms, utility rooms etc) should be provided with higher levels of ventilation (normally mechanical fans and windows) than other rooms where suitably sized window openings and background (“trickle”) ventilators may suffice.

Still can’t decide?

Get in touch and we will endeavor to help you make a choice.

Timber Casement Windows using Toughened Safety Glazing

Toughened safety glazing – Building Regulations

Toughened Safety Glazing and Building Regulations

Toughened Safety Glazing is a very important factor in modern building regulations. You will need to take this into consideration when replacing your Timber Windows and Doors. You will also need to ensure you are complying with relevant regulations as Dwellings are required to be energy efficient.

Energy Efficiency

A method of achieving greater energy efficiency is to take steps to reduce the amount of heat that is lost through the glazing in both Timber windows and doors.

If you are to install windows and doors you should be aware that they need to comply with the requirements of the Building Regulations in relation to the amount of heat that can to pass through the glass and framework, which is measured as a U-Value.  This U-value should not be exceeded.

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increase property value with Traditional Timber Sash Windows

Increase property value with Timber Windows

Increase property value with Timber Windows

It’s a fact! Timber Windows are proven to increase property value and the cost of this refurbishment is surprisingly lower than you would expect!

If you purchase your Timber windows from a supplier and then hire a carpenter or window fitter to install them the price of the total refurbishment would be lower than if you requested a large national windows company to supply and fit them for you.

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