FAQs

Secondary glazing allows you to keep your original single-glazed windows whilst improving their thermal efficiency. This means your heat loss through your windows can be reduced dramatically, which in turn will help to keep you warmer and reduce your energy bills.

At Mitchell & Dickinson, we have over 15 years’ experience helping owners of period and listed properties. We know that installing secondary glazing and insulation is the best way to keep your home warm, reduce energy bills and reduce your carbon footprint.

CosyGlazing is Mitchell & Dickinson’s award-winning and advanced secondary glazing system developed especially for period and listed properties. It is an elegant, virtually invisible secondary glazing solution which provides you with warmth and comfort. The fully integrated CosyGlazing solution enables you to still open and close your windows as you always have. It’s completely removable for cleaning and maintenance, and so meets with conservation officers’ requirements, and there is no additional frame required like with traditional forms of secondary glazing.

Yes, there are DIY secondary glazing kits which you can find online, although we cannot vouch for their overall efficiency. If you do not need to ever open your windows then a DIY solution may be adequate, although of course it would not come with a guarantee and lifespans differ from product to product.

Period properties tend to have unusually shaped windows that are often not level and, as a result, a DIY solution can be tricky to install. Our CosyGlazing system is fully integrated with your windows. Your ironmongery and catches are modified to work with the CosyGlazing system to provide maximum efficiency. Your windows will be completely reengineered and fully draught proofed by our specialist craftsmen so they can open and close perfectly, and as originally designed.

With our CosyGlazing secondary glazing in place, you will feel the difference in warmth and comfort of your home immediately. Employing specialists to fit your secondary glazing ensures a professional installation, which is guaranteed, and saves you the stress of doing it yourself.

In most cases, secondary glazing is considered a “permitted development” and doesn’t require planning permission. However, exceptions may apply, especially in conservation areas or for listed buildings. We recommend checking with your local planning authority for specific guidance.

No, the design of the system is such that is should be virtually invisible from the outside and the inside.

We install a specially modified catch/stay that can accommodate the CosyGlazing units on the window. You will still be able to open and close the windows as usual with our award-winning system.

When we re-engineer your sliding sash we will add weights to accommodate the weight of the CosyGlazing unit that is attached to the frame of your window using magnetic tapes. Some modifications are also made to the meeting rails to enable the casements to pass each other with the CosyGlazing unit fitted to the frame. Some windows can be more challenging than others, but bespoke and hand-crafted solutions are what we do to the highest standards.

Most period homes have specific hardware such as monkey tail or pig tail catches and stays, and particular locks etc. We usually replace your original hardware with a like-for-like but modified alternative to meet the crafted CosyGlazing panel. But where we are required to, we can usually modify the original hardware where it is essential to the listing of the property. There are of course some situations where this is not possible and your surveyor can advise you accordingly.

There are two sources of condensation. The first is caused by warm, moist air from inside the room touching the cold glass and condensing. This is reduced by CosyGlazing but we cannot guarantee it will eradicate it completely. The second is caused by external sources of moisture from the building fabric such as from broken putty allowing rain to leak in under each pane of glass and settle on the lower glazing bars, particularly after rainfall. Secondary glazing traps this water in the void, which can cause condensation. Therefore when installing CosyGlazing, it is advisable to keep putty and paintwork in good condition. This also increases the life of the window.

The cost of secondary glazing varies based on factors such as window size, type and installation complexity (for example, flat panels won’t allow you to open your windows without removing the panel first but will be the lowest cost). For a personalised quote, please contact Mitchell & Dickinson.

The installation time depends on the project’s scope and complexity. Generally, secondary glazing installation is a quicker process than installing new windows. Our team of expert craftsmen at Mitchell & Dickinson strive to minimise disruption and complete installations efficiently.

The effectiveness of secondary glazing depends on various factors, including your original frame materials and installation quality. Mitchell & Dickinson offers CosyGlazing, a high-quality bespoke secondary glazing solution tailored to meet specific needs and providing optimal performance. It is made to fit your specific windows using a material called plexiglass, which has a guarantee of 30 years.

Both secondary glazing and double glazing offer unique benefits. Secondary glazing is often preferred for heritage properties, where preserving the original window aesthetics is crucial. Mitchell & Dickinson can guide you in choosing the most suitable option for your property based on your preferences and requirements.

Secondary glazing enhances thermal insulation, reducing heat loss by up to 70% and improving energy efficiency The amount of heat saved depends on factors like the quality of installation and the type of material used. Mitchell & Dickinson’s CosyGlazing secondary glazing solution is designed to optimize energy efficiency and has a U value of 1.7.

Magnetic secondary glazing is a convenient and effective option for owners of period and listed properties or where the homeowner wishes to retain the original windows. Its performance depends on the quality of materials and installation. Mitchell & Dickinson offers its high-quality bespoke magnetic secondary glazing solution called CosyGlazing, designed to provide optimal thermal and , where required can also provide optimal acoustic benefits.

CosyGlazing is perfect for sash and casement windows in period homes and listed properties, but can also be fitted to every type of window including metal and stone mullions as well as doors with glazed areas, such as French doors.

Yes with the CosyGlazing integrated secondary glazing solution you will be able to open and close your windows just as you always have done. However, if you have metal windows we may need to design a bespoke solution to provide for window opening.

Yes, your CosyGlazing secondary glazing can be removed using suction lifts which are provided by Mitchell & Dickinson for all installations. You can then clean your original windows and the CosyGlazing units before popping them back on.

Yes, CosyGlazing can be matched exactly to your current window colour. We can use your original paint colour to create a CosyGlazing unit complete with our Colour Match trim so that the secondary glazing blends in completely with your window.

In most cases, we can handcraft a solution to enable your shutters to work with our CosyGlazing system.

Mitchell & Dickinson’s policy is always to restore rather than replace in all aspects of its work. We are often able to design a bespoke sealing solution. However, some metal or leaded windows may require the input of metal/leaded window specialists.

When we complete your survey, the surveyor will request information on your current energy usage and bills. We can then calculate financial and energy savings projections, which we will send to you with your insulation quotation.

Being much stronger but softer than glass, plexiglas can get scuffed by abrasives. However, scuffs can be polished out and, in our experience of fitting over 1,000 windows, we find that in normal use CosyGlazing does not scuff. Unlike early forms of perspex, plexiglass is fully UV-proof and carries a 30-year manufacturer’s guarantee against UV damage.

Mitchell & Dickinson has been testing magnetic tape for 15 years with no weakening of magnets. The adhesive is a very high-quality adhesive tape made by TESA which has a very long life. On rare occasions, it has been known to delaminate on specific surfaces which contain high levels of oils (such as linseed oil, for example).

When we install insulation measures, we will paint any areas that will be affected during our work to make good to the existing finish. If, for example, your windows are decorated to a specific colour, we will need details of your paint finish so that we can match it.

Where your windows have not been decorated for some time you may find that the areas we make good are to a different shade of paint. Customers are advised to consider this and may wish to arrange for decorating to take place after our installation is completed to get a matching paint finish.

Mitchell & Dickinson does not provide a full painting and decorating service. However, we do so occasionally as part of a major installation, under special circumstances and subject to a separate detailed quotation for decorating.

Decorating is not recommended in winter months. To protect timbers and prevent water ingress, paint needs to form a strong bond with timbers. The wood needs to be dry when the paint is applied. In addition, each coat of paint needs to cure, which takes longer in wet and cold conditions. The optimal time of year for full painting and decorating is between April and October, as these are generally the dryer and warmer months of the year.

Where we are doing substantial restoration work followed by CosyGlazing you may prefer to arrange for decorating to take place after our installation is fully completed.

Where we are installing draught proofing and CosyGlazing only, and restoration work is minimal, there is a slight advantage to decorating before we arrive, as it will be quicker and easier for your decorators to do their work before ours. However, in most cases, we’ll need to remove staff beads on sash windows, which we will then repaint as part of our work.

Where customers wish to arrange for decoration in advance of our installation, we will need to be sure that all paint finishes are completely dry and any cure time for specialist paints has been observed as per the manufacturer’s instructions before we arrive to complete your installation.

Please note: the instructions on the paint tin are for drying and over-coating times, however, paint takes much longer to cure fully. Therefore, we recommend an absolute minimum of one week after decorating is finished, and two weeks should you be decorating at colder times of year. Some oil-based or specialist heritage paints can take a month or more to dry completely.

If you have any particular paint colours or newly decorated joinery, we will need to match that same paint to paint the areas we disturb when we complete your installation. With that in mind, you will need to provide us with paint details (make and colour) if you require us to supply paint. Or you will need to ensure that the correct paint is readily available for our craftsmen on arrival.

Our craftsmen can provide the paint for standard white gloss or satin finishes, but any special white shades will need to be matched exactly where a specific finish is required.

External painting and decorating:

Most good decorators already know that a professional external paint job forms a durable, protective skin against the elements and that stops all moisture from penetrating the putty and timbers. The more coats of paint that are applied the greater the strength of the paint seal to withstand intense sunlight and the expansion and contraction of the timbers across the seasons. It’s interesting to know that some joinery firms supply their windows with 15 coats of paint! If only two or three coats are applied there is a greater chance that sun will break through the seal within two to three years. It is therefore advantageous to paint every two to three years initially and build up a thick layer of paint, and after that decorating can be done every five years or so.

A poor paint seal will mean rain can penetrate the paint and enter the putty and timbers. This will gradually saturate the timbers and soak through to the inside. Saturated timbers are one of the causes of condensation on the inside of the original glazing. It can also result in long-term waterlogging of timbers, which take a long time to dry out and can result in rotten windows. It is therefore important for external painting that the paint seal goes over the timber and over the edge of the putty and bonds well onto the glass to prevent rainwater ingress between the putty and the glass in future.

It is widely recommended that, for good maintenance, wooden windows and doors are repainted once every 3 to 5 years depending on environmental conditions. Properties in marine or semi marine conditions for example will require more frequent painting than those in sheltered, built up residential inland areas with little weathering. Usually the south or south west elevation of a property will require more frequent repainting than others as the southerly elevations ‘get all the weather’ i.e. intensity of sunlight in summer, and wind and rain in winter compared with the north facing elevations.

Many professional painters and decorators will undertake epoxy resin repairs to rotten glazing bars and other joinery components before painting. Putty repairs must be undertaken, where required, before painting so that water ingress is prevented and a complete seal to the external elements is achieved.

Internal decorating:
It is important to ensure that windows are kept open until dried completely and that excess paint is removed to ensure that windows are not painted shut or become sticky/difficult to operate. When we have completed your installation, your windows will have been completely re-engineered to open and close smoothly (where they were designed to be opening windows) and it is a shame if decorating afterwards results in sticky windows or windows painted shut.

Similarly, your decorators mustn’t paint the draught-proofing brushes installed in your windows (routed into the frames, or in the parting and staff beads) or the sash cords in sash windows, as this will greatly reduce their life. Once painted, the little brushes are compacted together, become brittle, and can even break off. This means they will no longer form a good seal to work effectively to prevent draughts and insulate your home. Once the sash cords are painted, they no longer run as well on the pulleys that they rely on to operate smoothly. This means our work to give you smooth and easy opening windows is undone.

It is better to avoid painting the ‘B’ tape (the grey magnetic tape adhered to your actual window frame) when decorating, but if a little paint gets onto the tape then it will not impact its magnetic polarity.

If you want to paint your grey tape white, or a colour to match your windows, you can do so provided you apply a coat of white Hammerite Smooth metal paint before any other paint to match the colour of your windows. Hammerite Smooth is the only paint that adheres to the magnetic tape and acts as an undercoat for your preferred paint type and colour.

Draught proofing is a process that involves sealing gaps and openings around and in windows and doors to prevent cold air from entering and warm air from escaping. This is achieved by fitting draught strips and other products to improve thermal performance. This helps create a more comfortable and energy-efficient internal environment.

The draughtiness of a building is determined by the amount of air that can pass through the external fabric – walls, roof, floor, windows and doors. This is called air permeability. Most listed and period buildings are permeable, ie they were not designed to be completely sealed from the external environment. However, the important factor is not the permeability itself but the rate at which air passes through the building.

If your home is well draught proofed this exchange and movement of air is reduced. Common signs that your home may benefit from draught proofing include noticeable drafts from doors and windows or other small gaps in the fabric, high energy bills, and difficulty maintaining a consistent and comfortable temperature when the heating is on. Our experts at Mitchell & Dickinson can assess your property to determine the most effective draught proofing solutions.

Different products and levels of expertise will achieve varying levels of effectiveness. Mitchell & Dickinson use durable and long-lasting materials suited to the fabric of your home, and apply our superior craftsmanship to fit them. We estimate that our full draught proofing service will reduce draughts by approximately 70% in a typical period building. We don’t aim for a 100% reduction as traditional buildings need a certain amount of background ventilation so they can ‘breathe’, meaning that moisture does not get trapped.

Draughts (or air infiltration) are often one of the biggest sources of heat loss in a building. In a typical ‘unimproved’ period building (one that has not had modern insulation measures applied) we estimate the draughts cause approximately 30% of total heat loss. To accurately measure the sources and rate of draughtiness (or air infiltration) an air pressure test is required.

However, most occupants know where the draughts come from and where they are worst because they can feel it! Windows, doors and chimneys will normally be responsible for the majority of the draughts. Mitchell & Dickinson’s surveyors will help you identify the draught sources and their contribution to your building’s thermal performance.

Yes, draught proofing is a versatile solution that can be applied to various types of windows and doors, including sash windows, casement windows and timber doors. Mitchell & Dickinson offers tailored draught proofing options to suit different architectural styles and materials. Leaded windows and stone mullions present particular challenges but in most cases we can reduce draughts using our Cosy Glazing secondary glazing system.

The cost of draught proofing depends on factors such as the size of your property, the number of windows and doors, and the extent of draught proofing required. Remember investing in energy efficiency measures should save you money in the long term as you won’t have to use as much energy to keep your home warm. For a personalised quote, please contact Mitchell & Dickinson for a consultation.

Absolutely. Draught proofing is a valuable solution for older or historic properties, helping to enhance comfort without compromising the integrity of original features. Mitchell & Dickinson specializes in providing draught proofing solutions that respect the character of heritage buildings.

While some draught proofing products especially DIY products are applied to surfaces of windows and doors, Mitchell & Dickinson’s draught proofing solutions are designed to be discreet and preserve the aesthetic appeal of your windows and doors. Our range uses durable rubber window and door seals fitted into elegant timber beading, routed-in door brushes and concealed-brush beading for sash windows. It looks attractive, unobtrusive and, most importantly, does the job. Our Our goal is to enhance energy efficiency without compromising the visual charm of your property.

Yes, draught proofing can contribute to noise reduction by improving the fit of of windows and doors against their frames, and closing up gaps. While it may not eliminate all noise, it can significantly improve your home’s acoustic insulation. Secondary glazing can help too.

The installation time for draught proofing varies depending on the size of the project and the number of windows and doors being treated. Our experienced teams works efficiently to minimse disruption, and we’ll provide a timeframe during the consultation process.

While some DIY draught proofing solutions exist, professional installation ensures optimal results. Mitchell & Dickinson’s team has the expertise to assess your specific needs and provide a tailored draught proofing solution that addresses your home’s unique requirements.

Yes, draught proofing is a key element in improving energy efficiency by minimising heat loss and reducing the need for constant heating. This can lead to lower energy bills and a more sustainable home.

Common types include fibreglass, cellulose, spray foam, rigid foam boards, and reflective insulation. However, at Mitchell & Dickinson, we prefer to use environmentally friendly sheep’s wool insulation for under floors, ceilings and lofts. This natural material has many beneficial properties including a 60-year life compared to 15 years for glass wool, and an increase in insulation properties in damp conditions. It’s treated with natural borax to prevent damage from pests, not irritating to skin or respiratory systems, supports British sheep farmers – improving economic resilience – and uses little energy in manufacture.

Common signs include fluctuating indoor temperatures, high energy bills, draughts, and uneven heating or cooling. Mitchell & Dickinson can carry out a full property survey to establish where your home is losing heat and could benefit from insulation.

Insulation helps regulate indoor temperature, reduces energy consumption, lowers utility bills, enhances comfort, and contributes to soundproofing and pest control.

Savings vary depending on factors like climate, existing insulation, and energy usage, but it can range from 10% to 50%.

Some insulation types can be DIY, but others may require professional installation for safety and effectiveness. If you choose to insulate your home with Mitchell & Dickinson we’ll take care of everything for you – from establishing what insulation solutions you need, installing the insulation and advising you on further things you can do to reduce heat loss from your home.

Insulation lifespan varies but can last anywhere from 20 to 100 years depending on the material and conditions. Mitchell & Dickinson’s sheep’s wool insulation typically lasts for around 60 years.

Health concerns may include skin irritation or respiratory issues during installation. Safety concerns include fire hazards for certain insulation types. However, Mitchell & Dickinson’s Thermafleece insulation is treated with natural borax to prevent damage from pests and is not irritating to skin or respiratory systems.

Proper insulation should be balanced with ventilation to prevent indoor air quality issues and moisture buildup. When we do your property survey, we will make sure that any insulation measures we suggest are balanced with proper ventilation.

Yes, eco-friendly options include recycled materials like denim or cellulose, as well as natural materials like our Thermafleece sheep’s wool insulation. When you choose Mitchell & Dickinson insulation you can rest assured that you are opting for an environmentally friendly option.

Well-insulated homes are often more attractive to buyers due to lower energy costs and increased comfort, potentially increasing resale value.

Regular inspections for damage or deterioration, especially in areas prone to moisture, can help maintain insulation effectiveness.

Loft insulation works by creating a thermal barrier that reduces the transfer of heat between the inside of a building and the outside environment. It’s usually installed in the loft or attic space, directly beneath the roof. The primary goal of loft insulation is to improve energy efficiency by minimising heat loss in the winter and heat gain in the summer.

Insulating your loft is a fantastic way to reduce heat loss in your property. The insulation acts as a barrier, helping to retain the warmth generated within your home and reducing your energy bills. It helps to maintain a more consistent and comfortable indoor temperature, reducing the need for heating in the winter and cooling in the summer. An energy-efficient home with proper insulation is often more attractive to potential buyers and therefore may contribute to an increase in the value of your property.

The amount of energy you can save by insulating your loft depends on various factors, including the existing insulation, the climate where you live, and your heating habits. On average, it’s estimated that a well-insulated loft can result in energy savings of up to 10% on your heating bills.

The specific energy savings will vary, but loft insulation is generally considered a high-impact, cost-effective measure to enhance the energy efficiency of your home. 

Draughts (or air infiltration) are often one of the biggest sources of heat loss in a building. In a typical ‘unimproved’ period building (one that has not had modern insulation measures applied) we estimate the draughts cause approximately 30% of total heat loss. To accurately measure the sources and rate of draughtiness (or air infiltration) an air pressure test is required.

However, most occupants know where the draughts come from and where they are worst because they can feel it! Windows, doors and chimneys will normally be responsible for the majority of the draughts. Mitchell & Dickinson’s surveyors will help you identify the draught sources and their contribution to your building’s thermal performance.

Yes, damp is caused when insufficient insulation leads to temperature differences between the indoor air and the loft space. When warm, moist air from inside the house comes into contact with the cold surfaces in the loft (such as the roof or walls), it may lead to condensation. This can contribute to dampness and create an environment conducive to mould growth.

Good quality loft insulation and adequate ventilation is crucial for maintaining a balanced moisture level in the loft space. Without proper ventilation, dampness may become a problem.

There are several different types of loft insulation available, including fiberglass insulation, mineral wool insulation, cellulose insulation and reflective foil insulation. One of the most eco-friendly types of loft insulation is made from natural sheep’s wool.

This natural and eco-friendly material has many beneficial properties including a 60-year life compared to 15 years for glass wool, and an increase in insulation properties in damp conditions. 

Products such as Mitchell & Dickinson’s eco-friendly sheep’s wool loft insulation are treated with natural borax to prevent damage from pests, are not irritating to skin or respiratory systems, support British sheep farmers – improving economic resilience – and use little energy in manufacture. Sheep’s wool insulation is also biodegradable, reducing its environmental impact at the end of its lifecycle.

While it is possible to install loft insulation yourself, it’s often worth hiring a professional to ensure it’s installed correctly and effectively. They will be up to date on the latest building regulations and will have the correct specialised equipment to complete the job. They’ll also have knowledge of achieving the desired thermal resistance and understand the required density and thickness of the insulating material.

Yes, and we recommend that you do because sloping ceilings have very high heat loss per square metre. This is because they usually consist of a sheet of plasterboard, a 100mm ventilated gap between the rafters, then battens, felt and tiles. If you compare this to an 18-inch wall or 12 inches of loft insulation, it becomes clear how little insulating effect they have, making them responsible for the coldness you’ll often find in these rooms.

Mitchell & Dickinson’s sloping ceiling insulation consists of thermal laminate boarding, a high-efficiency insulation board with plasterboard attached which is applied to the underneath of the sloping ceilings by screwing through to the rafters. Gaps around the edges are then filled and the whole area re-plastered. 

Window restoration involves repairing and refurbishing existing wooden or sash windows to restore their original beauty and functionality. This process typically includes repairing damaged wood, replacing broken components, and applying new finishes. Restoration preserves the historic character of the windows and is often more cost-effective and sustainable than full replacement.

Restoring wooden or sash windows allows you to retain the charm and character of your home while improving energy efficiency and functionality. Additionally, restoration is often more environmentally friendly and can be more cost-effective than replacing windows entirely.

In general, wooden or sash windows with signs of wear, damage or deterioration can benefit from restoration. Common issues include rotting wood, broken or missing components, and poor energy efficiency. Our experts at Mitchell & Dickinson can assess the condition of your windows and recommend the best course of action.

Yes, our team specialises in restoring even the most severely damaged wooden or sash windows. We have extensive experience repairing rot, replacing damaged components, and restoring windows back to their former glory. Contact us for a consultation to discuss your specific restoration needs.

Yes, window restoration can improve energy efficiency by addressing issues such as air leaks, poor insulation, and damaged seals. Our restoration process includes draught proofing and other measures to enhance thermal performance, resulting in a more comfortable and energy-efficient home.

The duration of window restoration depends on factors such as the extent of damage, the number of windows being restored, and the project complexity. Our team works efficiently to minimise disruption and complete the restoration process in a timely manner.

No, window restoration is designed to enhance the appearance of your home by preserving the original character and architectural features of your wooden or sash windows. Our skilled craftsmen pay close attention to detail to ensure a seamless restoration that complements your home’s aesthetic.

Yes, our team has the expertise to replicate the original style and design of your wooden or sash windows during the restoration process. Whether you have historic or bespoke windows, we strive to maintain their authenticity while improving functionality and performance.

Yes, window restoration is a sustainable choice that helps reduce waste and conserve resources by extending the lifespan of existing windows. By avoiding unnecessary replacement and preserving the embodied energy in wood, restoration contributes to a more environmentally friendly approach to home maintenance.

To get started with window restoration for your wooden or sash windows, simply contact Mitchell & Dickinson to schedule a consultation. Our team will assess your windows, discuss your restoration goals, and provide recommendations tailored to your needs and budget.