guide to creating the perfect garden building

8/14/2019 Guide to creating the perfect garden building

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The Vivid Green guide

to creating the perfect garden building

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Contents

Index Page

Introduction 3

What is important? 3

Insulation 3

Glazing 4

Heating 5

Lighting 5

Size and shape 5

External finishes and materials 7

Foundations 7

Internal finishes 7

Planning 8

Other hints and tips 9

Gallery 10

Price guide 12

Further information 12

Other structures 12

Appendix A. Standards for sustainable buildings

Introduction

A garden building, particularly one you are going to use year round, is a major investment.There are a bewildering array of designs, styles and materials to choose from and, unlessyou have some experience of building, the choice may appear overwhelming. This guide isintended to help you make the right choice for your situation. As well as our own viewsbased on several years experience of designing and installing low energy buildings, weinclude links to independent sites and suppliers. We hope it is comprehensive but pleaseemail us with your suggestions for other relevant topics and any other feedback to make

this a better guide for everyone.

What is important?

If you are considering buying a garden building, whether office, studio, workshop, gym orhome cinema/play room, what should you look for? There are four main aspects toconsider:

insulationglazing

heating (& lighting )size and shapefinishes and materials

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Insulation

Insulation is fundamental; you will be sitting in an isolated structure with no rooms aroundyou so it is essential there is sufficient insulation to keep you warm in Winter and cool inSummer. Sufficient insulation is a subjective term so, given the isolated nature of the

building, there should be at least as much insulation as is required for a new house, if notmore. Gardens can also be surprisingly noisy: children, building work and traffic inparticular so if the insulation can reduce this too, that is a bonus. The table below showsthe standards required for new housing in the UK alongside the level of insulation in atypical garden building and what can be achieved with a higher specification.

Vivid Green 150 Vivid Green 100Bdg regsstandards

Typical GardenOffice/Room

ThicknessU value Wm-

/KThickness

U value Wm-

/KU value Wm-/K Thickness

U value Wm-

/K

Roof insulation 153mm 0.14 128mm 0.17 0.16 - 0.25 45mm 0.57

Wall insulation 128mm 0.17 78mm 0.28 0.30 - 0.35 45mm 0.57

Floor insulation 100mm 0.22 100mm 0.22 0.22 - 0.25 0 1.20Windows/doors - 1.15 pane - 1.15 pane 1.8 - 2.0 - -

- 1.80 frame - 1.80 frame - - 1.90 frame

Building Regulations Part L 2002 U value calculation: BRE U value calculation version 1.08. Calculation method: BS EN ISO 6946

What this means in practice depends on many factors such as construction method andmaterials, insulation type, quality of glazing, location, desired internal temperature etc etc.However, as a guide, the difference in heating bills between a 10 sq metre typical gardenbuilding and the Vivid Green 100 specification will be about 120 a year at current prices.

As well as potentially saving money, a higher level of insulation creates a more comfortable

environment:

smaller differences in temperature during the daymore even temperature throughout the year (cooler in Summer, warmer in Winter)

There are many different types of insulation on the market with many claims about thesustainability of the different types. For an unbiased guide go to: www.greenspec.co.uk

Glazing

You will probably want a good deal of glass to create a light interior but be careful there isnot so much that you roast in Summer. It is surprising how little glass you need to givesufficient light and generate a little warmth (solar gain) when the sun is shining. If someof the windows face South, it is helpful to have a good overhang on the roof or a brise-soleil to shade the windows in the height of Summer.

While on the subject of glass, good quality windows and glazed doors pay dividends. Glassis a very poor insulator and even double glazed units let through about 6-7x as much heatas a well insulated wall. So, choose windows with a U value (the heat transfer co-efficientof materials) better than the 1.8Wm2k required by the UK Building Regulations to reduceheat loss. Where possible, check the whole frame U value rather than just the centre

pane value since a poorly made frame can let out a lot of heat. Special coatings and Argonfilled gaps between panes are available as well as triple glazing and special arrangementsto reduce sound transmission.

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http://www.greenspec.co.uk/http://www.greenspec.co.uk/


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www.energysavingtrust.org.uk/Home-improvements/Home-insulation-glazing/Glaz-ingwww.greenspec.co.uk/html/product-pages/vikingdouble.phpwww.viking.ee/en/products/

Apart from their contribution to heat loss, the quality of win-

dows and doors will have a big impact on your enjoyment of thespace. Especially if you are leaving valuable equipment in thebuilding, have a look at the locks on doors and windows. Aredoors triple point locking? Can the windows be locked at all andideally, can they be locked in a slightly open position?

Hardwood windows are expensive but there are many othercheaper options which also provide long life. Check on thequality of the timber treatment which should ideally be appliedin the factory rather than on site. Are the beads which hold inthe glass nailed or pinned? If nailed, the nails are very likely to

rust, stain the timber and let in water. The best windows haveno nails and a metal bottom bead which is the one which alwaysrots first.

Factory treated and painted softwood windows are aneconomical option which should not need re-painting in lessthan 10 years but Aluminium clad timber is never likely torequire painting.A couple of opening windows on opposite sides of the buildingwill create a good through draft but the other windows can befixed pane. Make sure several windows have trickle vents to

ensure adequate ventilation and that any glass below 800mmfrom the floor is safety glass.

Heating

Heating options are many and varied but one of thesimplest and most comfortable is underfloor electricheating which gives a very even temperature and willallow you to set the thermostat several degrees below thenorm. Other benefits include:

no wall space lost to radiators/heatersno hot surfaceseven temperature throughout

compatible withalmost any flooring.

If close to the house it may be possible to install a wet heating system ie: underfloor hotwater heating which, depending on the efficiency of the boiler may be a very economicalsolution.

http://www.ebeco.com/en/index.phpLighting

Lighting a well designed building providing plenty of natural light is not a major concern

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http://www.energysavingtrust.org.uk/Home-improvements/Home-insulation-glazing/Glazinghttp://www.energysavingtrust.org.uk/Home-improvements/Home-insulation-glazing/Glazinghttp://www.greenspec.co.uk/html/product-pages/vikingdouble.phphttp://www.viking.ee/en/products/http://www.ebeco.com/en/index.phphttp://www.energysavingtrust.org.uk/Home-improvements/Home-insulation-glazing/Glazinghttp://www.energysavingtrust.org.uk/Home-improvements/Home-insulation-glazing/Glazinghttp://www.greenspec.co.uk/html/product-pages/vikingdouble.phphttp://www.viking.ee/en/products/http://www.ebeco.com/en/index.php


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and, except for winter, artificial light should not be needed during daylight hours. If youwant stylish, low energy lighting then there is now a good choice including lights fromthese two companies: http://www.tp24.com/ http://www.greenled.co.uk/Size and shape

This is largely down to personal taste but there are some technical considerations. Flatroofs have a bad reputation but, properly designed with a high quality roof covering this

type of roof should last just as long as a pitched roof. Rubber membranes should give a15-20 year life if properly installed. As well as being more economical than a pitched roof,there are situations where it looks appropriate and it is one of the solutions to thechallenge presented by recent changes to the planning rules (see below).

A flat roofed art and music studio An apex roof clad with cedar shingles A pyramid shaped roof for doing the books

http://www.fra.org.uk/

Where space allows, a mono-pitch or pent roof can look very distinctive. If the pitch is atleast 14 degrees, preferably 18, then many options are available for covering includingcedar shakes and shingles, slates etc. Roofing materials with a high recycled content arecoming on to the market including eco-slates manufactured from recycled plastic andwhich are indistinguishable from the real thing. Cheaper options include asphalt tiles orsheet but neither has a very long life.

Firestone permaroof membrane Cedar shingles Recycled plastic eco-slates

www.permaroof.co.uk/ www.ajsmith.uk.com/cedarshingles www.athyecoslate.com/

Green roofs can look attractive though they need regular maintenance if they are not tolook very scruffy after a year or so and there is a significant premium to pay for theadditional materials. Also, if you are a keen gardener, you will probably want to collect thewater rather than reducing run off. A roof of 10 square metres will usually provide at least800 litres of rainwater at the start of the Summer. Black plastic guttering is fine, especiallyif not visible but galvanised steel offers a very attractive alternative.

The most economical shape for a garden building is square since

a long, narrow building will be much more expensive for the areaachieved. (A 16 sq metre square building requires a wall run of16 linear metres whereas an 8 x 2 metre building giving the same

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http://www.tp24.com/http://www.greenled.co.uk/http://www.fra.org.uk/http://www.permaroof.co.uk/http://www.ajsmith.uk.com/cedarshingleshttp://www.athyecoslate.com/http://www.tp24.com/http://www.greenled.co.uk/http://www.fra.org.uk/http://www.permaroof.co.uk/http://www.ajsmith.uk.com/cedarshingleshttp://www.athyecoslate.com/


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floor area, requires 20 linear metres of wall or 25% more!). However, it is largely a matterof personal preference, knowing how you will use the space and how the building will fitinto the garden and complement or enhance surrounding buildings.www.lindab.co.uk/framesetwww.greenroofstoday.co.uk

External finishes and materialsMany garden buildings are clad in timber but check tosee what type of timber is used and how muchmaintenance will be required. Softwood, especially if itneeds repainting or treating every other year, may notbe as cheap as it seems in the long run. Most peoplehave enough work maintaining their house withoutspending weekends maintaining another building! Adurable timber like Cedar will require no treatment andeven cheaper options such as Douglas Fir and Larchwhich are semi-durable will last for 15-20 years withouttreatment and much longer with the occasional coat of

preservative. www.trada.co.uk/index.html www.stourhead.com/sawn_timber.htm

Foundations

Most garden buildings are sufficiently lightweight not to need concrete foundations. 150-200mm of compacted hardcore over sub-soil is one option but a cheaper one is to removethe top layer of vegetation and install an interlocking plastic system which is backfilled withpea gravel. The eco-base from Swift Foundations is one such system designed specificallyfor garden buildings. Sloping sites, newly made ground and areas prone to flooding allrequire special attention so if in doubt ask your supplier or a structural engineerhttp://www.swiftfoundations.co.uk/

http://www.istructe.org/Pages/SeDefault.aspx

Internal finishes

On the inside, one of the major considerations is fire resistance. In most cases gardenbuildings do not have to comply with Building Regulations and provide 30 minute fireresistance. However, there may be circumstance where you would prefer the additionalpiece of mind which comes from a fire resistant interior. A fireboard/plasterboard finish isthe normal choice and will give a high quality surface which allows cabling and sockets tobe recessed. Other options are available and special finishes such as pin board can be veryuseful. Sundeala pin board is made from 100% recycled newsprint.

www.bbs-ltd.com/drylining_fire.htm

www.sundeala.co.uk/sundeala.htm www.norbord.com/SterlingOSB_Splash.shtml

Many people will use their garden building for music making andsound insulation therefore becomes an issue. This is a hugesubject and very technical. Differences between attenuation,absorption and transmission as well as different wavelengthsquickly confuse most people. Plenty of advice is available andsolutions need not be especially expensive. In general they alsooffer fire resistance. The following web sites explain how to goabout sound proofing.

http://www.acoustic-supplies.com http://www.soundstop.co.ukhttp://www.skanda-uk.com

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http://www.lindab.co.uk/framesethttp://www.greenroofstoday.co.uk/http://www.trada.co.uk/index.htmlhttp://www.stourhead.com/sawn_timber.htmhttp://www.swiftfoundations.co.uk/http://www.istructe.org/Pages/SeDefault.aspxhttp://www.bbs-ltd.com/drylining_fire.htmhttp://www.sundeala.co.uk/sundeala.htmhttp://www.norbord.com/SterlingOSB_Splash.shtmlhttp://www.acoustic-supplies.com/http://www.soundstop.co.uk/http://www.skanda-uk.com/http://www.lindab.co.uk/framesethttp://www.greenroofstoday.co.uk/http://www.trada.co.uk/index.htmlhttp://www.stourhead.com/sawn_timber.htmhttp://www.swiftfoundations.co.uk/http://www.istructe.org/Pages/SeDefault.aspxhttp://www.bbs-ltd.com/drylining_fire.htmhttp://www.sundeala.co.uk/sundeala.htmhttp://www.norbord.com/SterlingOSB_Splash.shtmlhttp://www.acoustic-supplies.com/http://www.soundstop.co.uk/http://www.skanda-uk.com/


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Plasterboard with a skim finish, recessed wiring and sockets provides a neat wall finish

Flooring is an important consideration too. Even with door mats and asking visitors toremove their shoes, there is the potential for the floor to get wet and muddy after the walkdown the garden. Carpet is, therefore, generally not a good idea but rubber or one of themodern linoleum products is a practical alternative: relatively cheap, easy to clean andhard wearing. Wood can also be good though grit and dirt can quickly scratch the surface.For a hardwearing surface, rubber is a good choice with a huge range of colours andpatterns available: www.jaymart.net/sarina.phpwww.nora.com/com/uk/products.html

Planning

The UK Government changed the planning rules relating to outbuildings on 1 October 2008so that, within 2 metres of any boundary, no structure (even a shed) can be higher than2.5 metres. http://www.planningportal.gov.uk/wales/genpub/en/1105619048902.html .With the need to raise the building off the ground plus the thickness of floor and roofinsulation, this presents an interesting design challenge. Flat roofs are an obvious answer.With headroom between 2075 and 2150mm (6 9 to 7). buildings such as those belowoffer a simple solution with adequate headroom for most people.

Penthouse 8 Penthouse 7.5

However, more attractive roof shapes are possible and the following sketches give an ideaof the options available if the building can be sited at least one metre from the boundary.

Flat roof with lanternThe simplest way of adding headroom and light is alantern. Glass lanterns can be very expensive butpolycarbonate versions offer a great alternative.Double and triple skinned versions offer superior

thermal and sound insulation. Headroom is typically2075 to 2150 (6 9 to 7) plus an extra 300-500mm(1 -1 7) under the lantern.http://www.nationaldomelightcompany.co.uk/

Shallow hip

A shallow pitch of at least 15 degrees offers theoption of cladding the roof with cedar shingles and

just a few more degrees opens up lots of optionsincluding eco-slates (imitation slates manufacturedfrom recycled plastic). Because of the need for a

slope, the height of the walls (eaves height) isreduced but greater headroom can be achievedthroughout the rest of the building. Typically

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http://www.jaymart.net/sarina.phphttp://www.nora.com/com/uk/products.htmlhttp://www.nora.com/com/uk/products.htmlhttp://www.planningportal.gov.uk/wales/genpub/en/1105619048902.htmlhttp://www.nationaldomelightcompany.co.uk/http://www.jaymart.net/sarina.phphttp://www.nora.com/com/uk/products.htmlhttp://www.planningportal.gov.uk/wales/genpub/en/1105619048902.htmlhttp://www.nationaldomelightcompany.co.uk/


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1800mm (5 10) at the eaves, headroom increases to 1930mm (6 4) 500mm in from thewalls and is 2600mm (8 6) in the centre.

Shallow hip + gablets

When the garden is a little bigger there is thepotential to add gablets to the roof: triangular gable

ends. These can be left solid but using triangularwindows makes a very attractive roof shape andprovides additional light. Headroom is similar to theshallow hip design above.

Both shallow hip designs require one wall to be insetby 600-1000mm to allow installation of doors. This creates an attractive porch or verandadepending on size.

Other hints and tips

A porch offers some protection from the rain for you and yourpapers, computer etc while you open up.

Install twice as many power points as you think you will need (4 doubles as a minimum)

When running the power cable from the house to the garden building, run several lengthsofethernet, telephone and alarm cable at the same time even if you are not going touse it.

Conclusion

We hope you have found this guide useful. It is designed to answer most of the questions

which arise when people consider installing a building in their garden. The advice and in-

formation is intended to be objective but, since we believe that there is more value to be

had from a building which is comfortable all year round and requires little maintenance,

there is an inevitable bias towards high levels of insulation, high quality materials and com-

ponents and low maintenance finishes and products. If, in the long run, this approach

saves customers money and a few tonnes of CO2, so much the better. We hope you find

your space for life as rewarding as we find ours.

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Gallery: examples of bespoke designs

Flat roof office, Harpenden; the prototype! Shallow pitch roof to bookbinding workshop, London

Apex roof office, Aldeburgh Flat roof studio, Exeter

Pitched roof clad in cedar shingles; Surrey Pent roof office in London

Pent roof office, Oxfor

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Bespoke designs to meet current planning restrictions on height

Standard designs to meet current planning restrictions on height

Penthouse 8 Penthouse 7.5

Price guide

Most customers requirements are so specific that a bespoke design is the only was to meettheir needs. However, standard designs are an economical option when economy is moreimportant. Standard designs (see gallery) work out at 9-10,000 including VAT for 7.5-8sq metres internal floor area.

Investment in a bespoke design depends on roof shape and covering, number and size ofwindows and doors etc. but, as a rough guide, allow 1500 per square metre for up to 8square metres, reducing to 1300 a square metre for up to 15 square metres. Forbuildings in excess of 25 square metres, prices can reduce to approx. 1000 a squaremetre including VAT.

Prices include design, delivery, foundations, installation, internal wiring and finishes etc.The only exclusions are trenching and cabling between house and garden building andpainting.

Further information, installations and testimonials

For more information contact Neil Johnston on 01582 469076 or [email protected] or visit the web site: www.vividgreen.co.uk. A small building is onpermanent display at Townsend Nursery, Townsend Lane, Harpenden, AL5 2RH. We alsohave a growing number of installations of all shapes and sizes throughout the country soplease call us to find one near you

Feedback

The content of this guide is based on those questions most often asked by customers and

those enquiring about garden buildings. If there are topics you would like covered pleaselet us know.

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mailto:[email protected]://www.vividgreen.co.uk/mailto:[email protected]://www.vividgreen.co.uk/


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Other structures

Larger buildings

The design principles and construction techniques used in our garden buildings are appliedto larger structures up to 300 square metres to provide comfortable, efficient, lowmaintenance structures for a variety of uses.

A WC and shower block for Scout and Guide camp site A dormitory for a residential centre

A concept design for a holiday eco-lodge A 50 place nursery

Pavilion

Timber framed and clad with

canvas roof liner and synthetic

tensioned fly sheet. One double

and one single bedroom plus

sleeping/play loft. Additionalinsulation offers scope for year

round use. Separate brochureavailable.

Canvas lodges

Timber framed, canvas covered

lodges for Summer/one season

use. Timber floor, windows and

doors. Simple, robust

accommodation for campers,cyclists, walkers, summer camps

etc. Separate brochure available.

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Appendix A. Standards for sustainable buildings

Not particularly relevant for garden buildings but if you are interested in more sustainableconstruction, there are many claims for green buildings but how do you know which onesreally mean something? We claim that our garden offices, studios and workshops are lowenergy because we design them to at least achieve the standard of insulation required fornew housing as defined in Part L of the Buuilding Regulations. Most clients opt for the

Penthouse 100 spec but some are persuaded by the higher level of comfort and reducedheating costs from adopting the higher Penthouse 150 spec. For larger buildings there areseveral standards which are worth considering.

BREAM has been around for a long time and now encompasses a range of assessments formany different buildings.

http://www.breeam.org/

The Government issued the Code for Sustainable Homes last year which, as the name sug-gests, relates to housing with Level 3 the minimum required for publicly funded housing

and Level 6 the aspirational goal.

http://www.communities.gov.uk/planningandbuilding/buildingregulations/legislation/englandwales/codesustainable/

Finally and, in my view, most relevantly, there is the system being promoted by the Associ-ation of Environment Conscious Builders (AECB). This is very simple to understand withboth a prescriptive and performance based approach and plenty of practical advice on howto use the standards. Essentially Silver should be the minimum to which anyone considersbuilding with the Gold standard somewhat higher in performance than even the GermanPassiv Haus standard.

http://www.carbonlite.org.uk/carbonlite/

Whether you adopt one of these standards as a goal in its own right or use the guidance asa way of improving an existing design, the benefits can be significant. As with all building,incorporating energy saving measures at an early stage in the design is far easier than ad-aptation or retrofit in the future. And, in most cases, the premium can be as low as 5-15%of the capital cost for a lifetime of savings.

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http://www.breeam.org/http://www.communities.gov.uk/planningandbuilding/buildingregulations/legislation/englandwales/codesustainable/http://www.communities.gov.uk/planningandbuilding/buildingregulations/legislation/englandwales/codesustainable/http://www.carbonlite.org.uk/carbonlite/http://www.breeam.org/http://www.communities.gov.uk/planningandbuilding/buildingregulations/legislation/englandwales/codesustainable/http://www.communities.gov.uk/planningandbuilding/buildingregulations/legislation/englandwales/codesustainable/http://www.carbonlite.org.uk/carbonlite/


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guide to creating the perfect garden building

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