Materials

Timber

The correct specification of timber is essential when undertaking any joinery project. For long term durability of our windows and doors, we use the following timbers:

  • Red Grandis: Red Grandis is a highly durable laminated material. To learn more about Red Grandis, click on the video link below or contact us
    for more information.

  • European Oak .
  • Accoya: A modified timber with the highest durability rating and an extended warranty period on the coatings. Accoya is the only timber available with a warranty of up to 50 years. Contact us for more details.
  • Sapele a very stable and durable tropical hardwood that is very well suited to all joinery.

For kitchen and furniture projects we use a combination of Veneered Panels, and a variety of solid timbers such as Oak, Beech, Poplar, Sapele and Black Walnut which are suitable for interior joinery .

Glazing

We use energy efficient glazing products that help to reduce CO2 emissions and protect the environment. All glazing units meet a minimum U value to comply with current Building Regulations  - the U value represents the Thermal Loss through the glazing unit and is influenced by:

  • The coating on the glass – As standard we use Planitherm Total glass (Click here for more information) which has a very good U-value coupled with excellent solar gain performance and a neutral look.
  • The type and width of spacer bar between the 2 pieces of glass – The spacer bar forms the perimeter of the glass and provides the spacing between two panes. Properties with double glazing units installed within the last 10 years will probably have an aluminium spacer, which provides poor insulation and give a lower U-value. As standard, we specify a 'warm edge spacer bar' which is manufactured from a thermally efficient material and reduces the thermal bridging effect at the edge of the glass giving a much improved U-value.
  • The medium in the cavity (gas or air) – Depending upon the unit specified the insertion of either Argon or Krypton Gas will improve the performance of the glazing unit. Krypton can provide a better performance over Argon but generally the we only specify Krypton when the cavity width is very small such as in a slim line or a triple glazed unit.

Glass Types

The Acoustic performance of a glazing unit is affected by the thickness of the glass, the gas cavity width and the material used in the centre of laminated glass. Acoustic glass can be specified where noise from a busy road nearby is a problem.

Where security is an issue, we can specify the use of laminated glass which provides additional security over toughened glass.

The glass is put through a toughening process to increase its strength and safety. As standard all fully-glazed doors are supplied with toughened glass. Any window that sits below 800mm from the floor will also require toughened glass for safety reasons.

We can offer a choice of obscure patterned glass options . Click here for more details.

About Paints

All of our wooden windows and timber doors are supplied fully painted or stained prior to installation, using a high performance micro-porous coating system. This provides maximum protection to the timber, whilst allowing it to breathe and with a stain finish it will let its natural characteristics show through.

By spray painting before installation, we can  provide a consistent coating to all areas of the window or door,  preventing moisture ingress, premature breakdown of the glazing units, premature frame decay and the overall aesthetic qualities of the window are increased.

We offer a very wide range of paint colours and stains and can offer a very near colour match to any brand of paint such as Farrow and Ball and The Little Greene Paint Company which are very popular choices for our products but are not suitable for spray application.

Paint

Opaque Paints

Opaque finishes (paints) give a solid colour . See colour chart here. The pigmentation of opaque paints protects the surface from UV light damage. White provides the most effective UV protection. The darker the paint, the greater the solar heat gain and risk of resin exudation and timber movement and hence the maintenance of dark painted windows will be increased.

  1. Exposure conditions can vary significantly in the UK. South facing elevations, coastal sites, and sunny exposed locations will, for example, all reduce to some extent the life to first maintenance. The lifetimes quoted are intended to give a reasonable guide in average UK conditions.
  1. Sunlight (UV) degrades the lignin in the timber surface, shortening maintenance cycles. The pigmentation of the coating inhibits UV degradation in much the same way that sun creams protect exposed skin. If the pigmentation is low, as in light translucent shades, the protection factor is less than more heavily pigmented coatings such as whites and opaque colours. This is reflected in the maintenance frequency. Care is also required with very dark colours, such as blacks, which have high heat absorption in direct sunlight. At high temperatures, resin bleed and surface checking can cause problems with some timber species and require more frequent maintenance.
  1. Good joinery design is critical to long term performance. In particular, sharp edges should be eliminated. Glazing Beads must be coated all round, end grain sealer should be applied during manufacturing.
  1. Coated surfaces should be regularly maintained and washed down, at least once per year, to remove surface dirt and debris.
  1. Some “chalking” of the paint film will occur over time due to the natural erosion of the microporous paint film. This is quite normal and does not detract from the system performance.
  1. The timber species used in construction will also affect paint system durability. Some timbers naturally exude tannin from knots, which stains the topcoat or liquid resin which seeps through the coating leaving a sticky residue on the surface. These problems are normally seen after installation and though aesthetically unappealing, do not detract from coating performance. If this occurs, minor repairs can be carried out to restore the appearance and integrity of the coating by following our maintenance guidelines.

 

Stains

Translucent stains will show the grain structure of the timber underneath. See stains chart here. Because they are susceptible to damage from UV light, the lighter the shade the more frequent re-coating will be required. Colourless coatings are available but will be very susceptible to UV damage and hence we are only able to offer very limited warranties on clear translucent coatings.

Many factors can influence the durability of exterior coatings, and the following points should be noted:

  1. Exposure conditions can vary significantly in the UK. South facing elevations, coastal sites, and sunny exposed locations will, for example, all reduce to some extent the life to first maintenance. The lifetimes quoted are intended to give a reasonable guide in average UK conditions.
  1. Sunlight (UV) degrades the lignin in the timber surface, shortening maintenance cycles. The pigmentation of the coating inhibits UV degradation in much the same way that sun creams protect exposed skin. If the pigmentation is low, as in light translucent shades, the protection factor is less than more heavily pigmented coatings such as whites and opaque colours. This is reflected in the maintenance frequency. Care is also required with very dark colours, such as blacks, which have high heat absorption in direct sunlight. At high temperatures, resin bleed and surface checking can cause problems with some timber species and require more frequent maintenance.
  1. Good joinery design is critical to long term performance. In particular, sharp edges should be eliminated. Glazing Beads must be coated all round, end grain sealer should be applied during manufacturing.
  1. Coated surfaces should be regularly maintained and washed down, at least once per year, to remove surface dirt and debris.
  1. Some “chalking” of the paint film will occur over time due to the natural erosion of the microporous paint film. This is quite normal and does not detract from the system performance.
  1. The timber species used in construction will also affect paint system durability. Some timbers naturally exude tannin from knots, which stains the topcoat or liquid resin which seeps through the coating leaving a sticky residue on the surface. These problems are normally seen after installation and though aesthetically unappealing, do not detract from coating performance. If this occurs, minor repairs can be carried out to restore the appearance and integrity of the coating by following our maintenance guidelines.
  1. Oak joinery is often specified with a clear finish in an attempt to preserve its factory appearance. Unfortunately, oak will rapidly discolour in sunlight and darken if moisture penetrates unprotected joints end grain. Oak’s natural durability means that these issues rarely cause a performance problem with the joinery, but aesthetically can be unattractive.

We can supply a system which compliments the features of Oak and gives performance levels comparable with light translucent systems, however regular inspection of of coating every 12-18 months is highly recommended to maintain the aesthetics and dis-colouration of the timber.

The poor quality of many wooden windows installed in houses in the latter half of the 20th century, taught a generation of home-owners that wooden windows need constant maintenance. This led to a huge demand for UPVC windows and doors but many home-owners have since discovered that UPVC quickly dis-colours, become brittle with age,  and unlike wood, cannot be easily disposed of.

Traditionally windows were painted with lead based paint. The joints were liberally coated  prior to assembly but this coating system had a tendency to crack, flake and peal which meant that the windows needed to be redecorated on a regular basis.
Today,  timber windows and doors that are supplied fully painted or stained by the manufacturer will last significantly longer before they need to be re-painted. This is due to extensive research and development within the paint industry with rigorous field tests being carried out under extreme conditions and also due to better joinery practices which optimise the performance of these new generation of coatings. 

 When do you need to paint your windows ?

Just like a car, a wooden window will require maintenance from time to time. The easiest way to  keep a service schedule is to leave the item unattended until a fixed time has passed. With a car this will be every six to twelve months,  depending on how much the car is used and the mileage that is clocked up.

In the case of timber windows, the mileage can be equated to the amount of weathering that the paint or stain coating is getting. This is governed by the climate and the level of shelter that the window has.

Certain areas on a window are far more vulnerable to getting wet or damp than others. Water will  gather on the lower areas of a window frame, the lower glazing beads and the cill . If the coating becomes damaged in these areas then moisture will be absorbed through the end grains and the wood will swell causing damage to the coating.  This will attract more moisture and exacerbate the problem if left unattended.

If the coating becomes damaged on the lower part of the window you should follow our remedial instructions for redecoration on these small sections. A small amount of work in the short term, will save a lot of time and effort in the long term.

Below are examples of Damage to Paint Coating caused by Water Ingression. The coating has become flaky and brittle and is allowing moisture to be absorbed by the timber substrate. If left unattended, the condition will worsen.

North facing windows are generally prone to colder and damper conditions which can lead to the growth of algae and mould. This can damage the coating and can result in de-lamination of the coating. Areas affected by algae and mould growth should be treated with a solution of one part sodium hypochlorite (household bleach) to two parts water. Allow the solution a minimum of 20 minutes to work before washing off with clean water and a stiff nylon bristle (not metallic) brush. Allow to dry. This should be done at least every 6 months.

Click here to view our Recommended Maintenance Schedule for Timber Windows and Doors

Oak Joinery

Oak joinery is often specified with a clear finish in an attempt to preserve its natural appearance. Unfortunately, oak will rapidly discolour in sunlight and darken if moisture penetrates unprotected joints. Although these issues do not cause a performance problem with the joinery, aesthetically they can be unattractive.

Our Oak windows and doors are finished with a coating that compliments the natural features of Oak and gives protection levels comparable with a light translucent stain, however Oak is a timber that demands special attention and regular inspection and care of the coating every 12-18 months is required to maintain the aesthetics and prevent dis-colouration of the timber.

If you are considering installing Oak Windows and Oak Doors, our standard maintenance cycles are increased. Further information is available upon request.

Case Studies

Click on images below

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Contact Us
Email: info@isisjoinery.co.uk
Telephone: 01981 580237 or
0845 644 3785
Fax: 0844 376 9979
Isis Joinery Ltd, Ross on Wye, Herefordshire.
Company Reg Number: 5708071
VAT Registration Number 881 503524