Mercia Haven Double-Glazed 28mm Log Cabin 4.0 x 4.0m

Now Only £2,829.99 GBP inc VAT & FREE delivery*
Usual price: £3189.99. You save: £360.00
11% OFF
Product Code
In Stock. Home delivery within 28 days by 20th October (estimate)
Free Delivery?
Delivery will be FREE for this item to your location
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Unit Price (inc VAT): £2,829.99

Add your options & accessories, click the for details:

1. Installation (building only - code 300LC)

Manufacturers Installation Service By selecting this option, an expert assembly team will install the product for you. A solid, level concrete or paving slab base must be prepared in advance and accessible for the installers to carry out the assembly.

2. EcoBase Base Kit (for 12x12ft approx) - DIY ORDERS ONLY

EcoBase Plastic Base kit 4x4m (64 tiles) A sturdy base kit made from interlocking modular plastic tiles, complete with a weed suppressing membrane. Delivered independent of the building within 2 working days.
Product Total: £2,829.99
In Stock

FREE* Home delivery within 28 days

Check your location for the Mercia delivery service and cost: *A distant location may attract a delivery surcharge


A beautiful, sizable log cabin made from 28mm interlocking, tongue and groove timber logs. With this upgraded model you gain the added benefit of double glazing, allowing you potentially all-year-round use.

The main access is through a double door which is flanked on either side by large opening windows. The roof of the Haven log cabin extends out beyond the front of the building as a shelter or sun shade.

Unlike full panel sectional buildings (like sheds), log cabins are built from the ground up with each log placed strengthening the building. As the weight of the building is focused at the foot of the walls, do make sure your base is suitably strong.

In common with this type of building, the logs are supplied untreated and One Garden recommends applying a coat of wood treatment to the building as soon as possible after installation.

Double glazed glass is supplied for the windows and green mineral felt is supplied to cover the roof.

Fixtures, fittings (including a key operated lock for the door) along with full instructions are provided as standard.


Detailed Measurements

External Width (max) 4120mm  -  13' 6"
External Depth (max) 5500mm  -  18' 1"
External Height (max) 2500mm  -  8' 2"
Footprint Width 4000mm  -  13' 1"
Footprint Depth 4000mm  -  13' 1"
Ridge Height 2500mm  -  8' 2"
Eaves Height 2100mm  -  6' 11"
Door Height 1900mm  -  6' 3"
Door Width 1550mm  -  5' 1"

Note: All imperial sizes stated are approximate, rounded to the nearest inch.


Material Wood
Cladding Interlocking log
Finish Planed
Colour Natural
Treatment Untreated
Door Position In gable end
Orientation 4.120m Gables / 5.500m sides (max)
Door Type Hinged double
Door Catch Key lock
Roof Type Apex
Roof Covering Mineralized felt
Roof Material 19mm Tongue & groove
Wall Material 28mm Interlocking log
Cladding Material Interlocking log
Floor Material 19mm Tongue & groove
Floor Joist Direction Side to side
Opening Windows 2
Window Dimensions 810x1100mm
Glazing Material Double glazed glass
FSC Certified Yes

Assembly & Care

Installation Self-assembly by customer
Persons to Assemble 2
Typical Assembly Time 1 Day
Fits Through Door (78x30 inch) Yes
Annual Treatment Yes by customer

Useful To Know

Warranty 10 Year Anti-rot
Recommended Use Leisure & relaxation
Includes A floor, felt, full instructions and fixings
Excludes A base, treatment & assembly

Our product specifications are given in good faith but can be subject to manufacturer change without notice. Should an attribute be of essense to your purchase, please feel free to contact us first for confirmation.



The Mercia Haven Double-Glazed 28mm Log Cabin 4.0 x 4.0m is delivered from central UK stocks held at our manufacturer. The manufacturer's own experienced personnel undertake delivery with careful handling to ensure the goods arrive in a perfect condition.


This manufacturer operates mostly 3.5 ton small flat-bed trucks. These will reach most locations an average car can. On occasion, a larger 7.5 ton lorry may be necessary.


Unloading will take place at the kerb-side or onto your adjacent driveway. Vehicles will not leave the public highway. A driver may be willing to carry the goods into your garden at their own discretion. Goods cannot be carried through your home, therefore if necessary please arrange some extra help privately.

Free Delivery

This manufacturer offers free delivery* within central, mainland England only. The above postcode checker will confirm this for you.

Delivery Period

Delivery will typically be made within the period quoted on this product. The manufacturer will notify you in advance by either telephone, text or email to confirm the date of delivery. On the morning of delivery, an email or text will be sent by the manufacturer to advise you of an estimated '2 hour delivery time slot'. Where possible, the driver may also call to update you on their progress. 

Pick A Day Delivery

Should your location qualify, during the checkout process you will be offered a real time calendar which will allow you to select a preferred delivery date. The manufacturer will endeavour to deliver on the date you have chosen. You will be promptly notified in the rare event that an alternative date is necessary for logistical reasons.

Orders with Optional Installation

The delivery of your goods will happen independently (as if for a self-assembly order) and prior to installation. Typically, the manufacturer's installation team will be scheduled to visit your address 2-3 days after delivery. You will be advised of the installation date by telephone. Note: Due to additional labour scheduling, an installation service option may add approximately 3 weeks to the overall delivery period. 

Extended Delivery

Less frequently serviced locations may be subject to an extended delivery period of up to an additional 14 days. These distant locations include; Northern Ireland (BT) and Scottish Highlands (AB, IV, KW, PA & PH).

Offshore Delivery

Offshore locations are not serviced for this product. We cannot deliver to; Guernsey (GY), Western Isles (HS), Isle of Man (IM), Isle of Wight (PO30-41), Isles of Scilly (TR21-25), Jersey (JE) and Shetlands (ZE). Other Scottish islands, for example those under selected IV, KA, KW, PA & PH post codes, also cannot be serviced.

Distant Surcharge

Due to additional zone fees, certain distant locations can only be serviced at a surcharge (at cost). The above post code checker can confirm if a surcharge will apply.

These locations include (except log cabins):


ZONE 2 (AB,PA21-40,PH21-41) = £99.99

ZONE 3 (IV1-40,KW1-14) = £119.99

These locations include (for log cabins):

ZONE 1 (CF,DD,DG,DT6-8,EH,EX,FK,G,KA,KY,LD,ML,PA1-19,PH1-20,PL,TA,TD,TQ) = £59.99

ZONE 2 (AB,BT,LL,PA21-40,PH21-41,SA,SY,TR) = £239.99

ZONE 3 (IV1-40,KW1-14) = £359.99

Small Drop Fencing Orders (of less than 3 panels and/or gates)

To maintain a free delivery service for Guardian-branded fencing products, you must place at least 3 fence panels or gates (can be mixed) in your basket to proceed; 1 gate and 2 panels for example. Orders of a lesser quantity will automatically incur a small drop delivery charge of £15.00, supported by a warning notice on the basket page.

Notes & Information

Product Notes

This log cabin is supplied untreated as standard. To maintain its warranty you should protect the external timbers with a quality wood preservative, immediately after installation.

Image Notes

The larger 5.0x5.0m Haven model is shown, which we do not currently sell. We unfortunately do not possess an image of this 4.0m variant. The imagery may show products which have been dressed for photography purposes.


Price Watch

We work tirelessly to ensure that our extensive product range is competitively priced through regular monitoring. In the rare event that you find the Mercia Haven Double-Glazed 28mm Log Cabin 4.0 x 4.0m from another online retailer at a lower price then please let us know, we'll do our best to match or even beat it!

Simply submit your Price Watch enquiry using the form below, being sure to complete all fields. On receipt, we will verify that the competitors' offer is available to purchase, like-for-like and delivery inclusive.

Within 1 working day we will confirm One Garden's keenest offer to you, whether that's to beat, match or even congratulate our competitor. Go on, challenge us...

For timber protection and to maintain the manufacturer warranty, you should apply an external preservative treatment immediately after assembly of this untreated log cabin.


  • Extensive 28mm log cabin with double glazing and large canopy
  • Standard 28mm interlocking tongue & groove logs
  • Double glazed opening windows
  • Green mineralized roofing felt as standard
  • Sturdy 19mm tongue and groove roof
  • Quality smooth-planed softwood throughout


warranty-10-year-anti-rot image

10 Year Anti-Rot Warranty
An assurance from the manufacturer that their timber product, if maintained according to their re-treatment policy, will resist rot within a 10 year period.

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FSC Certified
The Forest Stewardship Council promote responsible forest management. The manufacturer will have used FSC certified timber from managed resources.

assembly-professional image

Professional Installation (optional)
Some products have installation available as an option. For an extra charge, professionals will come to your property to install the product. An appropriately sized, firm and level base will need to be available for them to install.

treatment-untreated image

Commonly relating to timber, this reflects that no form of preservative treatment has occurred. To maintain the timber's lifespan a preservative should be applied once exposed to the elements.

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Interlocking Log
Forming the basis of log cabin construction, interlocking logs are notched rails which 'lock' together where they cross. Each has a tongue and groove (formats do vary) to create a near-continuous joint.

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Mineralized Roofing Felt
A garden building roofing felt in its commonest form. Coated externally with small stone flakes or grit to deter the effects of weathering.

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Double Glazed
Two sheets of glass with a sealed air pocket in between. Offers superior insulation and heat retention while also being extremely tough to break.

doors-key-lock image

Key Lock
A common security device enabling a door to be locked, which can only then be opened with the key provided. The image details a Press Lock, however the design and finish can vary by product.


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We encourage every purchaser of this product to submit a review. Customers are invited (by post-delivery email) to a web page where their genuine review can be placed.

Looking for something different? Try one of these Classic Log Cabins...

Mercia Haven 28mm Log Cabin 4.0 x 4.0m image Haven 28mm 4.0 x 4.0m

Now only £2469.99

11% OFF

£2799.99 You Save £330.00

A traditional 28mm log cabin with a large canopied roof and double doors

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Within 28 days

Everyday low price on our Haven DG 28mm 4.0 x 4.0m this Autumn.

Found a lower offer on the Mercia Haven Double-Glazed 28mm Log Cabin 4.0 x 4.0m? Oh no, please tell us!

As we aim to beat any like-for-like Mercia Classic Log Cabins online offer, please complete our online form (see 'Price Watch' tab above) and we'll be in touch.

If this Haven DG 28mm 4.0 x 4.0m doesn't quite fit-the-bill, take a look at our suggested alternatives above or the full Classic Log Cabins range for a greater choice.

© 2019 One Garden Ltd. Foundation House, Paddock Road, Caversham, Reading, Berkshire. RG4 5BY.
Registered in England & Wales No. 8939365. VAT No. 196 3243 88.
"One Garden" and the One Garden logo are registered trademarks of One Garden Limited. All rights reserved.

All prices include VAT. Product names and category filters show generic imperial sizes to aid comparison. For precise product size data see 'Detailed Measurements'. Selected distant regions may attract a manufacturer delivery surcharge; by location, brand or product. The 'Delivery' tab or 'Free Delivery?' postcode checker on each product will confirm if any such charge applies.