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Helena INSULATED Garden Office – Right

Approx. W5.5m x D3.5m / W18' x D11'

(Sizes shown are approximate & full sizes are shown in the product specification)

From £10,049.99 £11,514.99
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  • 120mm walls, highly insulated for year-round use
  • 28mm double glazed uPVC windows and doors
  • High internal eaves height - 2.18m (7' 1") front
  • Polyisocyanurate insulation for year round comfort

Found similar for less? Get in touch and we’ll beat it by 10%

Helena INSULATED Garden Office – Right Overview

The Helena Garden Office Right 5.5m x 3.5m, provides the same solution as an extension without the hassle of long term building works.

Opt for the sleek sliding patio door that creates a wide opening for entering. Alternatively, upgrade for FREE to a traditional single door with a side panel that comes with a 10-point locking system. Our garden offices are fully insulated from head to toe, ensuring you can use the facilities all year round.

Key Features

  • We DONT insulate with cheap rockwool / bubble wrap!
  • Advanced IzoPanel roofing. Strong & thermally efficient
  • Secure, Industry leading 10-point locking system
  • 10 Year guarantee on pressure treated timbers
  • Designed with the DIYer in mind for quicker install
  • All fixings included at no extra cost

Polyisocyanurate insulation is used within the core of the panels, which is a much better insulative material than polystyrene, Rockwool or bubblewrap like some competitors use. For added durability, the hood of the office is an industry leading Izo Panel waterproof roofing system.

Our luxury Helena Garden Offices also feature an advanced locking system on the door and 28mm double glazed windows. Start constructing the Helena on the day of delivery due to its easy to build panel system. 

Additional Information

To ensure the very best quality, we only use slow-grown White Spruce Timber, which is harvested in cold climates to ensure solid, dense log rings. This gives the wood superior strength and longevity, and also a much more consistent colour than the likes of Pine.

Despite the care we take in selecting the very best Timber available, it’s not like predictable brick or cold steel, this natural material has characteristics and quirks unique to every log.

Because our timber logs once fed water and nutrients back and forth from its roots to its leaves, its very nature is to be porous and swell up when it gets wet. Any wooden product will do this throughout its life, but there are a few things you can do to help limit this movement.

These include:

1. A great design!

  • Don’t worry, we’ve got this one covered. We’re experts when it comes to all things timber, so we have designed our products from the ground up with its natural properties in mind.

2. Water Repellent Treatment.

  • How you customise and decorate your product is up to you, however we would recommend that you use an appropriate water repellent treatment. This really helps minimise the amount of moisture that the timber can absorb. Therefore minimising the risk of any major movement.
  • (Please note: water repellent treatment is not the same as pressure treatment, which protects against rot and insect infestation, and which we guarantee for 10 Years!)
  • On pressure-treated timbers, you may notice some subtle striation marks. These marks sometimes appear during the drying process of timbers. Fear not! In time, the marks will begin to fade as the sun starts to lighten the wood.

Timber with Striation marks

3. Ventilation.

  • Keeping your timber building ventilated is no less important than keeping your house well ventilated. This is especially true if you plan to cover up your floorboards with something (double check with an expert, that the material is suitable to do so), as moisture can become trapped between layers of non-breathable materials and build-up, leading to floors becoming rotten.

4. Regular Seasonal Maintenance.

  • Whether you opt to build your product yourself, don’t be afraid to tighten the odd bolt here and there. Your product is a life improving investment, so it’s only right to give it some love and care from time to time. Make sure that it’s properly treated before the rainy months, and you make adjustments to doors and window frames, when needed.

Natural Timber Properties

After building your timber product, this natural construction will begin to ‘settle’. This means that you will likely see some natural timber imperfections appear. These types of natural imperfections can include:

Cracks

Cracked climbing frame timbers

Splits

Split Timbers

Shakes

Timber Shakes

Warping / Twisting

Expansion and Contraction

Please be aware that, as these are natural timber properties they are not considered as defects under our Terms & Conditions (for more information, check out our Terms and Conditions. However, in most cases, these imperfections will not impact the integrity or function of your timber product, and/or can easily be rectified. For advice on how to rectify these and for more support, please get in touch with our Customer Services Team on [email protected].

The inner walls of our garden rooms are made using a fire resistant fibreboard for increased protection. This is a hard-wearing material made from recycled paper fibres and Gypsum (Hydrous Calcium Sulphate). The fibreboard is supplied unpainted so you can design and decorate the interior of your garden room to your own individual style. This material is a good surface for paint and is easy to wallpaper.

fire resistant inner wall for garden rooms

There is nothing more annoying than being in the middle of building something and finding that you don’t have the right fixings to continue. We include all of the screws, nails and fixings that you will need to put your garden building together – not many of our competitors are that thoughtful. This eliminates the need to worry about the type of screws or the length of nails you might need to get started – it’ll all be with your delivery.

Fixings Included

All of the timber in this garden building has been responsibly sourced and pressure-treated to ensure it lasts. Pressure treatment forces the wood preservative into the timber rather than simply dip treating (essentially just covering the exterior) like many companies still do.

Unlike some competition, we can offer a genuine 10-year guarantee against wood-eating fungal and insect infestation on pressure-treated timber.

All our Pressure Treated timber is for Use Class 3.

10 Year Guarantee on Pressure Treated Timber

Our garden rooms are supplied with domestic standard uPVC windows and door frames available in White as standard or Anthracite Grey Wood Effect. So you can either tie in with your home frame colours or customise your office or garden room!

Not all double glazing is the same, and what truly makes our double glazing stand out among the rest is the sealed unit. We supply a 28mm, double glazed sealed unit. These units comprise of 2 panes of 4mm toughened glass on either side of a 20mm aluminium spacer bar, designed to absorb any moisture within the sealed unit, which could lead to condensation inside the glazing. These sealed units comply to BS EN 1279 standards. This EN standard covers the requirements for insulating glass units, including thermal and sound insulation. The sealed units are independently tested to show that they will not suffer from any form of condensation within the unit.

We’ve been manufacturing uPVC windows and doors for over 30 years – so we really know our stuff!

28mm Double glazing on Garden Offices

Our Garden Offices feature a very advanced roofing system manufactured by Izo Panel. The roof system combines a hard-waring, easy clean roof surface with an attractive grooved ceiling. They use a stiff polyisocyanurate foam core (a material that provides a very low thermal conductivity rating) joined together tightly with overlapping cladding in a trapezoidal profile which makes strong joints that prevent water ingress. Altogether the roof is waterproof, has great thermal characteristics and is uniquely strong. This Izo Panel is supplied in panels which are designed to be quick and easy to install.

 

Fully Insulated Roof For Garden office Fully Insulated Roof For Garden office

You don’t need us to tell you how important it is to have a garden room that is easy to heat, and maintain at the right temperature. Our garden offices feature polyisocyanurate insulation in the roof, walls and floor, creating the perfect space to use as a home office or lounge room. Polyisocyanurate is arguably the best thermal insulation that can be found in any garden building in the market, especially when compared to the more commonly found Rockwool, polystyrene, or foil backed bubble wrap that competitors are supplying. It is known for being a far superior insulative material.

You may ask why did we go to such lengths to design a garden office with such high spec insulation compared to other companies. It’s really quite simple, we know that you will be spending most of your time in your garden office, either working or relaxing with the family, so it’s important to be comfortable and satisfied with your purchase. Our insulation helps retain the heat in the winter and keep you cool in the summer, meaning you can use your office all year round. The heat retention properties also help you spend less on your energy bills, by allowing you to not have the heating for on, longer than what’s needed.

Energy Efficent Insulation for Garden Offices Dunster House

All of our garden buildings have pressure-treated floor bearers as standard. This treatment prevents the timber bearers from rotting for up to 10 years and causing your garden building to sink. Pressure treatment forces the wood preservative into the timber rather than simply dip treating (essentially just covering the exterior) like many companies still do. Who wants to have to annually deconstruct and re-treat the bearers each year!

Due to this costly but effective process, we can offer our customers a genuine 10-year guarantee against rot and insect infestation on the bearers.  We do however recommend applying a good quality water repellent to the timber to prolong the longevity of the timber. Shockingly many of our competitors still offer untreated bearers to keep their costs down, so beware!

All our Pressure Treated timber is for Use Class 3

Pressure Treated Bearers

Rotten Untreated Floor Bearers

The Helena Garden Office features a Patio Sliding Door with a walkthrough width of 0.66m or 2’2”. The door will not only let in plenty of natural light but will also make an attractive addition to your garden. The doors (and windows) also feature trickle vents to avoid moisture build-up when closed.

Sliding Patio Doors

Get your garden office up and running quickly and easily thanks to the full panels provided. No need to waste time building up walls or fixing doors together.

DIY Garden Offices Easy Build Panel System

Unlike our competitors, we only use high-quality spruce timber on our wooden products rather than cheap pine or mixed timber. Why do we use slow grown spruce rather than the much cheaper knotty pine alternatives?

Spruce is considered more stable as it expands and contracts less than pine. This stability means that the spruce timbers in our garden buildings minimise splits from appearing as the timber changes along with the weather.  We responsibly source all our timber, where it grows slowly in the cold northern regions. We all know the old adage of counting the rings to see how old a tree is, well our timber grows slower and takes longer to get to size meaning it has more rings in it. This means it has a tighter grain, and each ring helps prevent cracks and shakes from appearing in the densely packed timber.

Our wooden garden buildings and climbing frames really are built to last therefore we use only the highest quality, slow-grown spruce.  Spruce is much more resilient to warps and splits compared to its cheaper alternative pine. Being a whitewood, it doesn’t discolour anywhere near as much as pine so it is also much more aesthetically pleasing for a garden structure. Considered more stable, less knotty and resinous than pine, spruce will also produce a lot less sap. It is also less dense meaning it is not as susceptible to mould and rot.

Outdoor Living Slow Grown Spruce

Outdoor Living Slow Grown Spruce II

We can significantly undercut competitors offering uPVC options as we are a large DIY window and door manufacturer. We do not buy windows and doors from another company therefore we do not need to markup our prices and transfer the cost to our customers. Providing you with great value!

Grey exterior frames for your windows and doors will give a more contemporary feel to your garden office. We use domestic style uPVC for the frames of our office window and doors to add to the zero maintenance and long lasting overall effect of the structure.

Grey uPVC windows and doors

This garden building is under 2.5m high. Why does this matter? Under permitted development rights, buildings under 2.5m high can be placed as close as you want to a boundary (eg. a fence line) without planning permission. Garden buildings that are over 2.5m high need to be placed over 2m away from any boundary (eg. a fence line), which could lead to a lot of wasted space. If you want to find out more about permitted development rights see our planning guide

All our garden buildings have been designed on the basis that any competent DIY customer should have no problem installing a product themselves in a short amount of time. You do not have to be an expert at DIY to build a Dunster House garden building, as we do provide you with comprehensive pictorial instructions. We totally understand that DIY is not for everyone therefore, you may want to consider getting in touch with a local carpenter or handyman to install it for you. But before you do, check out our construction video and decide for yourself!

Moisture build-up inside any garden building is an issue. Moisture can lead to damp and mould settling in, rendering the building a health hazard. We have designed our garden offices to combat these issues at the source.

 

The floor supplied in the Titania and Helena range of garden offices also benefit from the moisture control we put in place. The floor structure starts with pressure treated bearers which form the lowest part of the garden building. On the bearers will then be fixed our unique floor panels. These are made up of a layer of WPC (Wood Plastic Composite) a material known to be highly resistant to rot and decay, a layer of polyisocyanurate insulation to prevent heat loss in the floor and lastly, we add a hard-wearing layer of MR P5 flooring.

 

Insulated office walls Insulated office Floor

Security is something that shouldn’t be overlooked when designing a garden office, especially when storing valuable equipment. Which is why we have included our industry leading 8-point locking system on the wide opening uPVC patio doors as well as multipoint locking windows which feature secure key locking handles.

Our 8-point locking consists of 8 hook bolts. All our windows feature a multi-point locking system consisting of mushroom-headed espagnolettes which move in opposite directions into metal keeps. Why would you risk your possessions by using less?

Locking Door System for garden offices

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We recommend a flat, level concrete base at least 100mm bigger on each side: e.g. A 4m by 3m building would have a base of 4.2m by 3.2m See more details here.

 

This garden room is well insulated, but a small electric or fan heater is a good idea to keep the building warm inside. If you choose to install electrics, speak to an electrician about heating.

 

We offer a genuine 10-year guarantee against rot and insect infestation on all pressure treated timber.

 

No, we do not have any showrooms or display sites. All business is completed online and via our website. If you do have any queries that haven’t been answered with the information provided online, please feel free to call our sales team on 01234 272445.

U-values tell us about the heat loss properties of the material you are measuring. The lower the number, the better insulated the Garden Building will be. Find out more here.

We recommend a flat, level base at least 100mm bigger on each side. e.g. A W4.0m by D3.0m garden building would have a base of 4.2m by 3.2m See more details here.

Often, an additional cost is buried within the price when offering finance, thus making your purchase higher priced. This is the reason we do not offer finance and feel that it would not be beneficial for our customers or us. However, we have come up with an alternative method for you where you can use a 0% interest-free credit card to pay off your purchase. For more information, see this article: Do we offer finance?

Dunster House commit to continuously improve the sustainability level of our sourcing, by favouring stricter more credible certification and verification standards, and sourcing requirements. We are committed to avoiding sourcing from unknown or unsustainable sources.

Where possible, Dunster House are committed to procuring wood products that have been certified against credible, internationally recognised standards for good forest management, to ensure that material originates from well managed forests.
In line with this, we preference products certified to the standards of FSC (Forest Stewardship Council) and PEFC (Programme for the Endorsement of Forest Certification).

What about illegal timber?

Dunster House are committed to sourcing only material that is produced, processed and traded according to applicable legislation.

What is your Environmental Responsibility policy?
Dunster House are committed to promoting responsible stewardship of the environment and its natural resources. We are committed to lessening the impact on the environment caused by our own activities, and those of our suppliers.

Do you have a Supply Chain Management policy?
Dunster House will ensure that information about suppliers and material is gathered as part of the RPP. We will ensure regular engagement with our suppliers to ensure compliance with UKTR requirements, working with them to ensure continuous improvements. We will also specify that, wherever possible, that material sourced is covered by FSC and PEFC, to ensure responsible forest management.

Yes, we do! Some postcode restrictions do apply however we are pleased to be able to deliver to many parts of Scotland.

For more information – Where Do We Deliver?

We do not currently offer installation. All our garden buildings have been designed on the basis that any competent DIY customer will have no problem installing a product themselves in a short amount of time.

You do not have to be an expert at DIY to build a Dunster House garden building, as we do provide you with comprehensive pictorial instructions. Also, if you prefer video tutorials, we do have a selection of videos on YouTube which will support you in building your product.

We totally understand that DIY is not for everyone and it can be very overwhelming to start building your own garden product. Therefore, you may want to consider getting in touch with a local carpenter or handyman to install it for you.

If you do take on the challenge to put your garden building together, we are always here to help. Do not hesitate to contact us at any stage of putting your product together and we can provide you with all the assistance you may need. Contact our customer service team via email at [email protected].

Owing to the multitude of possible configurations available for power and lighting we have left these offices for customers to supply and create their own, exactly how and where they want them.

This Garden Office contains floor, roof and wall insulation. The type of insulation we use is called Polyisocyanurate, which is proven to retain heat better than polystyrene or rockwool. This Garden Office also features 28mm double glazed units to aid in retaining heat.

Due to the unique design of a Dunster House product, in the vast majority of cases our garden buildings can be installed without the need for planning permission.

However, there are a few other factors to consider:

As all properties are different in size, shape and style we can only advise based on how we have designed our products, not on your property.

When to consider planning permission:

  • If the garden building exceeds over 2.5m tall – the majority of Dunster House buildings do not exceed this.
  • If you intend on putting an outbuilding in front of the main elevation of your property (as it was originally built or as it was on 1st July 1948) will require Planning Permission.
  • If you live in a listed or graded building
  • If you live in a designated area such as areas of outstanding natural beauty, national parks, world heritage sites and conservation areas.
  • If there is a possibility that over 50% of your garden would be taken up by outbuildings.

Click here for more information on Garden Building Planning Permission in the UK.

Still not sure?

If you are still in doubt, we highly recommend getting in contact with your local authority before making a final purchase.

It is 2.49m (8' 2")

A Garden Office is a garden building used to create an office away from your home, separating your work life from your home life.

A Dunster House Garden Office is made from slow-grown spruce or wood polymer composite, double glazed 4mm toughened glass, and polyisocyanurate insulation (SuperFOIL on our Dominator range), creating a thermally efficient, smart looking product.

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measurements for 5.5 x 3.5 garden office
  • Please Note: All sizes quoted are nominal
  • Overall External Dimensions: 5.46m x 3.57m (17' 10" x 11' 8")
  • External Width: 5.42m (17' 9")
  • External Depth: 3.25m (10' 7")
  • Internal Width: 5.18m (16' 11")
  • Internal Depth: 3.01m (9' 10")
  • Internal Area (m2): 14.76m2
  • Ridge Height: 2.49m (8' 2")
  • Internal Eaves (Front): 2.18m (7' 1")
  • Internal Eaves (Rear): 1.99m (6' 6")
  • Roof: Insulated Izo Panel
  • Roof Thickness: 135mm (100mm Insulated core)
  • Floor Thickness: 40mm Insulated Sandwich Panel
  • Roof U-Value (W/m2k): 0.21 W/m2K
  • Wall U-Value (W/m2k): 0.59 W/m2K
  • Framing: 70mm
  • Gaskets: On all Windows and Doors
  • Overall Wall Thickness: 121mm
  • External Timber Thickness: 15mm Shiplap Cladding
  • Insulation Thickness: 25mm
  • Floor Bearers: 35mm, Pressure Treated
  • Insulation Material: Polyisocyanurate
  • Internal Finish: 10mm Gypsum Fibreboard
  • Door Style: uPVC Patio Sliding Door
  • Door Material: Reinforced 5 Chamber uPVC Profile
  • Door Locking System: Multi point locking system with 6 pin euro cylinder lock barrel
  • Door Walkthrough Height: 1.91m (6' 3")
  • Door Walkthrough Width: 0.66m (2' 1")
  • Window Locking System: Multi Point with Mushroom Headed Espagnolettes
  • uPVC Colour options: White of Anthracite Grey Wood Effect
  • UPVC Colour: White included in price. Upgrade to a different colour
  • Glazing Material: 28mm Double Glazed, Toughened Glass
  • Timber: Pressure Treated
  • Please Note: All fixings needed for assembly are supplied. All wood is planed and pre-cut (with exception of trims), for quick and easy construction. No electrics or lights included.
  • Guarantee: 10 Years Against Rot and Insect Infestation
  • Approx. DIY Assembly Time: 4 - 5 Days* *This is an approximate time only, based on 2 people. Assembly time may vary depending on season/weather conditions, foundation type, ability of those constructing, etc

Helena INSULATED Garden Office - Right Ratings

Zak Laming

Great Garden Office.

Great product. Instruction could be a little clearer in places but overall good. Everything was there with nothing missing. Just one piece of trim fitted incorrectly which was easily rectified. No hesitation to order again

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Delivery Information

* Free delivery on orders over £200.

We deliver our products to mainland United Kingdom (England, Wales and most of Scotland). Some exceptions apply; these are illustrated on the map below.

Postcodes affected include:

  • TR
  • TQ6, 7, 8, 9
  • EX19, 20, 21, 22, 23, 38, 39
  • LD
  • PL10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35
  • SA
  • KW
  • HS
  • ZE
  • KA27, 28
  • IV1, 4, 6, 7, 8, 9, 10, 11, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 51, 52, 53, 54, 55, 56, 63
  • PA20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 41, 42, 43, 44, 45, 46, 47, 48, 49, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 80
  • PH32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44

Dunster House delivery map

Green – Free Assisted Delivery

Red – We are unable to deliver to these areas.

Purple – For orders to Ireland & Northern Ireland, please visit our Distributor in Ireland here.

Delivery Service

All of our products are delivered using our own fleet of vehicles, not sub-contractors. We have a large number of vehicles dedicated to delivering our quality products so we can guarantee maximum care is taken during the delivery process.

Our deliveries take place Monday to Friday between the hours of 8:00 am and 6:00 pm.

When the delivery vehicle is unloaded, it is important that you check to make sure all of the items and instructions have arrived and are correct. You will also receive a component list to check your items against. If anything is missing or damaged, it is essential that you note this on your paper work when you hand it back to the delivery driver.

Prices for our delivery services can be found on individual products.

Please note that goods will be delivered to the first point of contact at the front of your property e.g. on your driveway. This must be within 20m from the delivery vehicle (Safely Parked at Kerbside). Our team will be responsible for assessing the risk of carrying out delivery upon arrival at the property.

Should you require further information on our assisted delivery services, please click here to read our Terms and Conditions, alternatively you can contact a member of our Sales Team.

See the locations we deliver from.

Q: Where can I find more information?

A: If you have any questions regarding your delivery, you can telephone our Dispatch Team. Contact details for the Dispatch Team of your nearest branch can be found on your order confirmation. If you need to track your delivery or access your manuals in advance of your delivery, you can visit the Customer Log-In Area of our website.

Thank you for taking the time to read about our terms and advice during this period. We hope you can enjoy your Dunster House garden product for many years to come.

Why Buy From Us?

Buy with confidence! Established for over 30 years, you can rest assured of our knowledge and experience as industry leaders.

On pressure treated timbers*. We don’t dip-treat our timber unlike some competitors. Dip treatment isn’t as effective at protecting against rot and infestation!

All products are uniquely designed and of high quality with many industry leading features you will struggle to find anywhere else!

A UK company and family run business. Our products are designed  and distributed from our 11 UK distribution centres.

Many have bought from us over the last 30+ years due to our superior specification and the fact that our products are designed with the DIY market in mind.

Free delivery on most products*. Delivered to you by our own fleet of vehicles and dedicated drivers.

Inspiration/Customer Stories

Dean’s Garden Cinema Room

View Case Study

Ed’s Garden Music Room and Home Office

View Case Study

Andy and Rose’s Garden Games Room

View Case Study

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† Reference to Price on 22nd December, 2023

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From £10,049.99 £11,514.99
Save £1,465