Beginning your home improvement journey can be daunting. With new terminology and so much choice out there, it can be daunting – and not to mention alienating. To help, we’ve put together this FAQ section and answered some of your key questions.

Frequently Asked Questions

Find answers to some of the most asked questions below. We’ve got everything covered, from the difference in energy ratings right through to the construction of our roof tiles.

What’s the difference between PVC, PVCu and UPVC?

Absolutely nothing.

UPVC stands for Unplasticised Polyvinyl Chloride. It’s sometimes referred to as PVCU, though this is more prevalent on the continent than here due to linguistical differences. And sometimes, the ‘U’ is omitted completely.

UPVC is extensively used in the construction and home improvement sector as it’s a low-maintenance material and is resistant to chemicals, sunlight and oxidation.

What’s the difference between casement and flush windows?

The main difference is where the casement sits. On a standard casement window, the casement (the part of the unit that moves), sits proud of the window frame.

On modern flush windows, this casement sits level with the frame. This creates a neater finish which is clear to see if you compare the two different windows. Why not visit our showroom and see for yourself?

Should I choose Double or Triple Glazed windows?

It depends on what you want from your windows.  The obvious difference between double and triple glazing is the number of panes of glass within the unit – two for double and three for triple.

There are pros and cons to both options and ultimately, we’d recommend speaking with an ERG advisor to determine which would be the most suitable for your property.

Speaking generally, triple glazing is better at retaining heat and preventing cold spots. With an additional air gap, triple glazed windows can also help prevent noise from transferring into your property. Though if the acoustic rating is your key motivating factor, there are other solutions that you should explore.

What colours do your replacement windows and doors come in?

Thankfully, we’re able to supply our windows and doors in a variety of colours and finishes to suit any size and property.

For those with a traditional leading, we’re able to offer the standard range of white and cream. But if you prefer something modern, then we can offer an array of options including a selection of sleek greys and statement colours such as Chartwell Green or Steel Blue.

As well as colours, we can also provide windows and doors in a beautiful wood grain finish. This includes the dark tones of Rosewood and the lighter ones of Oak.

Also, it’s worth knowing all our windows are available in two colours. So yes, you can have one colour inside and another on the outside.

I hear a lot about energy rated windows. What does it all mean?

The Window Energy Ratings (WERs) use an easy-to-understand traffic light-style system to show how energy efficient your window will be, similar to the energy ratings you see when looking at appliances.

The ratings follow a scale from A+-G, with A+ being the highest and are defined by the BFRC Rating Scheme. This is the UK’s system for comparing the energy efficiency of windows and is universally recognised.

All new or replacement windows require a minimum WER of C or above. Ask an ERG representative for further information and they’ll be happy to talk through the performance of any of our windows.

What does U-Value mean?

A window’s U-Value indicates how well your window retains internal heat. U-Values are measured in Watts per square metre, of W/m2K. The lower the number, the better the window is at keeping the heat in.

All new or replacement windows must have a minimum U-Value of 1.6 W/m2K. If you’d like more information about how well different windows perform, ask an ERG advisor.

What does Secured by Design mean?

Secured by Design (SBD) is the official police security initiative that looks to improve the security of builds by designing out vulnerabilities.

Our manufacturing partner, Conservatory Outlet, is a registered member of Secured by Design and many of our windows and doors meet the rigorous demands of this police-backed standard.

Do you make your own windows?

All our windows are manufactured in the UK by our partner, Conservatory Outlet.

Conservatory Outlet is the leading fabricator of windows and doors and a supplier to a small and exclusive group of retailers, us included.

This close relationship allows us to retain close control over our supply chain and provide our customers in the Highlands of Scotland with the best selection of windows and doors around.

Are all composite doors the same?

No. Standard composite doors are typically 44mm deep and feature a foam inner that makes them reassuringly strong and secure.

At 48mm deep, Solid Core doors are slightly thicker than their standard counterparts and are made from laminated layers of timber. This makes them stronger and more durable

Solid Core composite doors on the other hand are deeper (48mm) and are made from laminated layers of timber, making them more secure and long-lasting than standard offerings. They are also finished in a UPVC skin and are therefore available in a variety of colours.

Can I have a different colour on the inside to the outside?

Yes! If you want grey outside and white inside, no problem. And the same goes for blue and green, or black and red. Or you could go mix and match two wood-look finishes. The choice is yours. An ERG advisor will be able to run down the colour options available for each door and work with you to create a unique door that matches the stylings of both you and your property.

How many keys do I get?

You’ll get three keys as standard. But if you need any more, just let us know when you order your new door.

Can I have the keys the same for multiple doors? (Suited)

Of course. Just mention this to us upon ordering and we can ensure that your keys are suited.

What does Secured by Design mean?

Secured by Design (SBD) is the official police security initiative that looks to improve the security of builds by designing out vulnerabilities.

Our manufacturing partner, Conservatory Outlet, is a registered member of Secured by Design and many of our windows and doors meet the demands of this police-backed standard.

What does a 3-star rated door barrel mean?

The 3-star grade is the highest rating available, making it the safest choice on the market. The cylinder itself is tested to help prevent break-ins. It features snap-secure technology which, with its lockdown mode, prevents the barrel from being compromised and thereby keeping your home safe.

Can French doors fold back completely?

They can indeed. Our French doors can be ordered and installed with an egress hinge which will allow you to fold the doors back.

Should I choose sliding patio or bi-folding doors?

This is a commonly asked question and there’s no real right or wrong answer – it depends on what you ultimately want. Sliding patio doors have slimmer than bi-folds, so even when closed you get a larger view of your garden. However, bi-folding doors fold completely back and open up your property to the outside, which is great for access.

What’s the difference between a conservatory, sunroom and an extension?

This is something we get asked a lot.

Recently due to advancements in construction and design, the clear differences between the three types of living spaces have blurred. Traditionally, a conservatory would predominantly be glass. We’re talking glass walls and a glass roof. However, it is possible to have a tiled roof conservatory or to introduce some dwarf walls to aid insulation.

Conservatories also have a reputation for being too hot in the summer and too cold in the winter. Thanks to glazing options improving, glass panes can feature coatings and coverings to ensure the room is at an ideal temperature all year round.

The main feature of an sunroom is its pillars. These can be either brick or aluminium and add a little extra privacy over a full-glass wall conservatory. Sunrooms also tend to feature a pelmet around the roof, which helps to insulate the room. And as for roofs? Well, anything goes! An sunroom can have anything, from glass lanterns to tiles and everything between.

On the other hand, an extension is purposefully designed to mirror the look and feel of your home. It will largely be brick and generally (but not always) is finished off with a solid roof. Modern extensions can feature full-length glass panels and Velux windows to aid ventilation.

Whatever it is you’re after, we’re able to help. If you still need some guidance, speak to an ERG advisor and we’ll be happy to design something that’s uniquely yours.

Should I choose a tiled or glass roof?

This depends on your property and how you want to use the room in question. If you’re after unobstructed views and plenty of natural light, then a glass roof is the way to go. Yet if you’re wanting a room for all-around use and extra privacy, then we’d suggest a solid tiled roof.

However, it’s possible to go for a hybrid between the two. You could go for a solid roof and add in either full-length glass panels, Velux windows or even a lantern. The choice is yours.

Will my conservatory or sunroom be too hot in the summer and too cold in the winter?

We know that the weather in the Highlands is a little more rugged than elsewhere in the UK and we’ve chosen our suppliers and products are with that in mind. All our living space products, roofs included, are designed and manufactured to be comfortable all year round.

Thankfully, gone are the days of polycarbonate roofing. Solar-controlled glazing options have made a real difference and help to regulate the temperate of your living space. If you’re concerned, however, then we’d recommend going for a tiled roof.

Do you manufacture your own roofs?

All our roofs are made by our partner, Conservatory Outlet.

Based in Wakefield, West Yorkshire, Conservatory Outlet is the leading manufacturer of living spaces and roof products in the UK.  Thanks to our close relationship, we retain close control over our supply chain and work with them to ensure everything that we sell is right for the unique demands of Highland living.

Can I choose different roof tiles to match my home?

Absolutely. Come and visit our showroom where we’ll be happy to go through the different options available. We can also offer a range of flat roof membranes and, if you’d like, we can even match your property’s existing tiles.

What is solar control glazing?

Solar control glazing is glass that features a coating that actively works to retain heat in your home whilst stopping external heat from transferring into your room. This type of finish helps to regulate the temperature in your living space and make it as energy efficient as possible.

We have several options available, all of which offer varying levels of light transmission and heat retention. To discuss things further, speak to an ERG representative who’ll be able to advise on what type would be best for your needs.

Can I match to my existing bricks?

We’ll always match brickwork where we can. Before any work starts, we’ll check this with you and ensure you’re happy to proceed.

Please bear in mind that your existing brickwork will have been exposed to the and as such, there may be some discrepancies between the old and new bricks due to the weathering process.

Do I need Building Regulations Approval?

Many extensions need some form of approval under current Building Regulations – but some don’t. We’ll take care of the entire process. We’ll send an experienced surveyor out to your home to go through, check and discuss any relevant details. We’ll also arrange for the Building Regulations by working with the local authority.

Do I need planning permission?

Extensions & Conservatories

You don’t require planning permission if the extension meets certain rules. This is called ‘permitted development’.

If your extension will have one storey, you don’t need planning permission as long as:

  • it’s located at the back of the house
  • it doesn’t go back further than 3 metres if it’s a terraced house, or 4 metres
  • if it isn’t the height of the eaves (where the wall meets the roof) is no higher than 3 metres
  • it’s not higher than 4 metres, including sloping roofs
  • it doesn’t cover more floor area than your house does
  • it doesn’t take up half the ‘curtilage’ – the grounds behind your home
  • it isn’t within a conservation area

If you want to add a porch to a front door, back door or side door on your house,
different rules apply.


You won’t need planning permission to add a porch to a front door, back door or side door on your house as long as:

  • its footprint (the total floor area it takes up) is no greater than 3 square metres
  • there’s at least 2 metres between the edge of the porch and any boundary facing a road
  • it isn’t taller than 3 metres
  • it isn’t within a conservation area

How long will it take to build my new living space?

It’s hard to put an exact timeframe on this as each project is unique and could be dependent on specific planning requirements. Please speak with a member of the team for specific timelines.

What is a test dig?

A test dig allows us to find out what the conditions on-site are. The results will determine what type of base and foundation is suitable and ensure we’re fully prepared to start the build process.

What is a cavity tray?

Cavity trays are a type of damp-proof course that bridges the cavity in a cavity wall and prevents moisture from permeating the inner wall.

Should I choose a tiled or glass roof?

This depends on your property and how you want to use the room in question. If you’re after unobstructed views and plenty of natural light, then a glass roof is the way to go. Yet if you’re wanting a room for all-around use and extra privacy, then we’d suggest a solid tiled roof.

However, it’s possible to go for a hybrid between the two. You could go for a solid roof and add in either full-length glass panels, Velux windows or even a lantern. The choice is yours.

Should I replace my frames too?

If you are getting a new roof for your living space, then it makes sense to replace your windows and frames too. Why get a modern and more thermally efficient roof if you’re going to hold onto your old, outdated and potentially drafty frames?

What is a replacement tiled roof made from?

A replacement solid roof system is typically prefabricated to help ensure the installation process is as quick and easy as possible.

The system itself comprises a pre-engineered, lightweight frame, insulating panels, insulated and fire-grade plasterboard, plywood and specialist membrane. The finish of the roof is either tiled to your choosing or solid panels.

What is a Clad over roof?

A Clad over roof is sold by other companies as a cheaper option. We recommend that these be avoided as they aren’t designed to bear much weight, which is a problem when it snows.

Other problems with a Clad over roof include:

  • Weight: Clad over solutions can be surprisingly cumbersome and too heavy for an existing conservatory structure. An old conservatory requires a lighter roofing system. The lightest solid roof that we can provide weighs around 31kg/m2

Tip: Always ask your installer to list the total weight of the new roof per square metre.

  • Fire Safety: Clad over systems don’t meet current fire safety regulations as they aren’t fire tested as part of a wider structure. Original structures vary from building to building and so any test would have been conducted on induvial components, not the complete project. Solid roofs must be classified as either AC, AB or AA per BS476-3.Tip: Before committing to any home improvement project feature a new roof, ask to see the fire safety certificate of the entire roof system
  • Building Regulations: Clad over systems generally don’t get Building Regulation Approval due to their poor thermal performance and/or structural integrity. This is separate from planning permission, which is often not required. When replacing a roof, you have to notify Building Control (including replacing a glass or polycarbonate roof with a solid option) to check it is structurally secure.

Tip: Check with Build Control that they have been informed about the impending works and keep your final Building Regulations certificate in a safe place!

Will my new roof still be too hot in summer and too cool in winter?

All our products are designed with year-round suitability in mind. A solid roof offers a fantastic level of comfort and modern glass roofs can be specified with solar controlled glazing to better regulate the temperature in your living space.

How much will it cost to replace my existing roof?

As always, it depends on the size and complexity of the project. However, expect to pay around £5,000 for a small conservatory roof and £12,000 for a larger one.

How long will it take to replace my existing conservatory roof?

It normally takes a couple of days to replace an existing roof.

Do I need planning permission to replace an existing roof?

Planning permission is not required yet Building Regulation Control is. A property cannot be sold without this important document.

Do I need Building Regulations Approval?

Getting Building Regulations approval means that you can be safe in the knowledge that your system has been installed correctly and has been checked by a government-accredited inspector. The inspector will check that the installation has been done correctly and the roof is both structurally safe and thermally efficient.

Having this certificate also means that if you sell the property in the future, there won’t be any issues with unauthorised or undocumented work.

Do you offer finance to help pay for home improvements?

Yes, we do. To make the project more affordable, we offer different finance options (subject to application and status). See our Finance Calculator for more details.

What do we need to do when our finance is approved?

If you are arranging your finance independently, just call us as soon as possible after it has been approved. If you’re applying for finance through us, we’ll inform you of the result directly.

What happens if finance is refused?

People get turned down for finance for varying reasons. Sometimes it’s because you’ve moved several times in the past few years.

If you are unable to get finance through ourselves, we’ll do our best to help. It might be worth trying another provider, especially if they have an existing relationship with you – e.g. your bank or mortgage provider.

I’ve applied for finance with ERG. How long will the approval process take?

Sometimes, we get an answer almost immediately. Other times, it might take a few days. If you’re waiting, don’t worry – the delay could be for any number of reasons and you shouldn’t be concerned.

ONLY AT ERG Scotland


Our collections are exclusive to ERG Scotland, you won’t find a like-for-like offer anywhere else.



Manufactured to exceptional standards in our state-of-the-art manufacturing facility.



All our products are manufactured in the UK by skilled craftsmen.



Ensuring the security of your home and family is built into everything we do.



Every promise we make, we keep. Every time. Our promises are bold and are there to assure you that we’re completely confident in our products and our service.


At ERG we realise the importance of gaining trust and not expecting it. We believe this is achieved through hard work, honesty, transparency of our services and valuing our customers.

Ethos of ERG Scotland

Our teams adhere to a strict ethos which is to achieve only the highest standards of excellence at all times. We listen to our customer’s needs and tailor our services to meet all individual requirements.

20 Year Guarantee

ERG Scotland is proud to be Scotlands very first to offer a 20 Year Guarantee. Not only that, you will also be covered for both moving and non-moving parts. Our confidence in our products and dedication to our customers means we’ll be there for you well into the future.

Price Promise

Giving our customers complete confidence in the price that they pay is very important to us. So, if you, or any customer, can find the same product specification and service commitment cheaper elsewhere, within 14 days, we’ll refund the difference.


Everyone is welcome to come in and browse around our showroom, where our friendly sales team will be pleased to help with any questions you may have.



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