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Dunster House Ltd.
Incorporated. 1994
25th anniversary logo
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Lines re-open tomorrow at 8:30AM
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Collection: Monday – Friday (9:00 – 17:00)
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Product Features
Garden Offices 10 Year Timber Guarantee
Garden Offices 10 Year Timber Guarantee II
10 Year Guarantee
All of the exterior timber of your Garden Office is pressure treated. We offer a genuine 10 year guarantee against rot and insect infestation on all of these parts. So you won't need to worry about little critters causing havoc or rot damaging the timber.
Garden Offices 28mm Sealed Unit
28mm Double Glazing

Our garden offices are supplied with domestic standard uPVC windows and doors frames in a range of four popular colours, which include, white as standard, grey wood effect, golden oak wood effect and rosewood wood effect. So you can either tie in with your home frame colours or customise your office!


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 for all our garden offices. 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 25 years – so we really know our stuff!


Garden Offices pressure treatment tank
Garden Offices pressure treated timber wood
Pressure Treatment, Not Dip Treatment

All of the garden offices in our Titania, Helena, Thedore and Lienne range are fully pressure treated as standard. We take the pre-cut lengths of spruce used on the exterior and place them in a large pressure treatment tank, where the timbers are impregnated with a non-toxic preservative. We add a brown colourant during this process, giving the timber a rich brown colour. By pressure treating the timber, we can offer a genuine 10-year guarantee against rot and insect infestation.


This treatment prevents the timber from rot, decay and insect infestation for up to 10 years. 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 only suggest that you apply a good quality water repellent to prolong the longevity of the timber.   


Many of our competitors offer untreated bearers to keep their costs down or charge extra. Who wants to have to annually deconstruct and re-treat the bearers each year?


Avoid Planning Permission Helena 4.3x2.7 Left
Avoid Planning Permission
All our Garden Offices are under 2.5m high so that under permitted development rights you can place the building within 2m of a boundary if you wish to. Please be aware that any building over 2.5m high needs to be placed over 2m away from any boundary. If you want to find out more about planning permission click here.
Tall Door Height Helena 4.3x2.7 Left
Tall walkthrough height
There's no need to 'duck' on the way in through our quality French uPVC doors. With a tall walkthrough height of 6'0" (1.84m) you’re free to move in and out of your office concussion free. Others have tried to copy us but include the doorframe as part of their walkthrough height.
IzoPanel Roof Breakdown Garden Offices
IzoPanel Roof - Panels Garden Offices
IzoPanel Roof
Our Garden Offices feature a very advanced roofing system manufactured by Izopanel.  They use a stiff polyurethane 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. 
Multipoint Locking Windows & Doors Patio Door Locking Garden Offices
Multipoint Locking Windows & Doors Window Locking Garden Offices
Industry leading window and door locking 
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 9-point locking system on the wide opening uPVC patio doors as well as multipoint locking windows which feature secure key locking handles.
Our 9-point locking consists of 8 hook bolts and a 6-pin euro cylinder. 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? 
Patio Sliding Door Helena 4.3x2.7 Left
Patio Sliding Door
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. 
Moisture-Resistant Walls and Floor Exploded Wall
Moisture-Resistant Walls and Floor Exploded Floor
Moisture-Resistant Walls and Floor

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 polyurethane insulation to prevent heat loss in the floor and lastly, we add a hard-wearing layer of MFP flooring.


Fire-Resistant Inner Wall Comparison Fireboard
Fire-Resistant Inner Wall
The inner walls of our Garden Offices are made using a fire-resistant fibreboard – a hard-wearing made from recycled paper fibres and Gypsum (Hydrous Calcium Sulphate). You can be sure in the knowledge that your Garden Office has increased protection from fire. The fibreboard comes unpainted, but you can decorate it to your taste, as it is a good surface for paint and is easy to wallpaper.
15mm Shiplap Cladding Garden Offices
15mm Shiplap Cladding
Unlike some we only use full length cuts of pressure treated shiplap cladding on our garden offices, which comes in a substantial thickness of 15mm. The advantages of using shiplap cladding is its robust, and sturdy.
Our cladding interlocks creating a strong watertight bond that allows rain to run off the office quicker, it also creates an attractive, professional appearance, that’s certain to wow potential clients if your running your business from home.
Garden Office Energy Saving Wall Panels exploded
Fully Insulated Building 

Our Titania and Helena garden offices feature polyurethane insulation in the roof, walls and floor. Polyurethane 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 or foil backed bubble wrap that competitors are supplying.


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.


Our Titania and Helena garden office range feature a unique Izopanel roof system, which combines a hard-waring, easy clean roof surface with an attractive grooved ceiling. This is filled in between with our insulation of choice – polyurethane. This Izopanel is supplied in panels which slot in to each other forming a water tight joint. This method of roofing is designed to not only be thermally efficient but quick and easy to install.

Pressure Treated Bearers Helena 4.3x2.7 Left Garden Offices
Pressure Treated Bearers
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!
garden office panel system
Easy To Build Panel System Helena 4.3x2.7 Left Garden Office
Easy To Build Panel System
Our walls are supplied in pre-fabricated panels, consisting of our 15mm pressure treated shiplap cladding which is attached to our 70mm thick framing. This framing is then filled with a layer of moisture resistant membrane and polyurethane insulation. Panels are then finished with a layer of Gypsum Fiberboard. 
What is a Garden Office?
A: 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, 4mm toughened glass and polyurethane insulation, creating a thermally efficient, smart looking product.
What Foundation Do I Need For This Garden Office?
A: 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.
Do You Offer Any Guarantees Or Warranties On This Product?
A: We offer a genuine 10-year guarantee against rot and insect infestation on pressure treated timber.
How High Is This Garden Office?
A: It is 2.49m (8' 2") high
Do I Need Planning Permission For This Garden Office?
A: Take our quick survey to find out! We also recommend you check the government planning portal.
Is This Garden Office Insulated?
A: This Garden Office contains floor, roof and wall insulation. The type of insulation we use is called Polyurethane, which is proven to retain heat better than polystyrene or rockwool. This Garden Office also feature 28mm double glazed units to aid in retaining heat.
Does This Garden Office Come With Electrics?
A: 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.
Does This Garden Office Need Treating?
A: This Garden Office is pressure treated so will not need retreating against fungal decay and insect infestation for up to 10 years. However, we do recommend treating with water repellant for timber maintenance.
Where Can I Visit You? Do You Have A Store Near Me?
A: We have 6 branches across the UK. Click here to find the nearest one! Please check with us before you visit if you are travelling to see a particular product.

Helena 4.3m x 3.3m is presently only on display in our Bedford Branch.

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

Scottish areas may be subjected to slightly longer delivery turnarounds, please contact us for details. FREE delivery on selected products over £200 to mainland England and Wales.

Delivery to postcode areas PL, TQ, TR, EX may take 1 week longer, beyond the delivery shown on the product page.

Delivery Price

Green - £19.99 delivery fee on all orders under £200.

Blue - Delivery to postcode areas PL, TQ, TR, EX6, EX7, EX20, EX21, EX22, EX23, EX39 may take 1 week longer, beyond the delivery shown on the product page.

Yellow - £59.99 delivery fee.

Orange - £84.99 delivery fee.

Red - We are unable to deliver to these areas.

Assisted Delivery

If you cannot provide an able-bodied person to offload the vehicle with the help of our driver, we can provide additional manpower with our Assisted Delivery Service. The driver will arrive with some help to unload the lorry, meaning that you can put your feet up.

Please note that items can be carried up to 50 metres from the kerbside to your place of choice as long as the route doesn’t go through a house (or any decorated building) and that there is sufficient space (at least 750mm wide) for the drivers to handle heavy pieces safely. Our drivers will be responsible for assessing the risk of carrying out a Two-Person Delivery upon arrival at the property. If they feel that there is no clear access as stated above, they will have to leave the items at the kerbside.

We offer this service on most items that are delivered, we do not offer this on our couriered products. Prices for this service can be found on individual products.

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

Scottish areas may be subjected to slightly longer delivery turnarounds, please contact us for details.

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!)

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, or have us do it for you, 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


Cracks On Wood


  • Splits

Splits On Timber Held With A Green Rounded Safety Cap

  • Shakes


Shakes On Wood Panel


  • Warping / Twisting

Warped wood panels, twisted Wood panels


  • Expansion and Contraction


Expansion And Contraction Of Wood On Garden Building


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 Ts&Cs here). 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


Similar sizes
Helena Garden Office - Right
Helena Garden Office - Right
W4.5m x D2.5m
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