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Garden Store |  General Information Pages |  How to Build a Base

Let us build your Shed Base or Summerbuilding base

Sheds and Summerbuildings Bases

It is always nice to get a new timber shed, playhouse, solar potting shed or summerbuilding in your garden but you do need a solid base for them to sit on to ensure you get the best life out of the building. The options are concrete, paving slabs, timber decking, timber joists or ProBases .

Which ever one you use you need to make the best job you can do. You may decide that you will get someone in to do this for you and if so, we can help. We can arrange for our fitters to build a timber base for you and will ensure that the base is level and will ensure a very long life for your building. They will make this base using pressure treated timbers and your building will sit on top of this base ensuring that your new building is well protected from any dampness coming up from the ground. This will help to ensure that your floor and garden building will last a very LONG time. All you need is a reasonably level piece of ground. However, it is possible to build even on uneven ground but you would need a special quote for this.

Base construction

The addition of our base construction service is the real big news and it is something that should be considered by everyone. It is vital to the longevity of your new shed, summerhouse or home office that it sits on a good solid foundation. Without this the life of the building will be severely reduced and you may find the building listing to one side, the floor bouncy and rotting, doors and windows sticking and the roof leaking.

Timber subframe base on sloping ground Timber subframe base for garden workshop

There are various methods of creating a suitable base ranging from concrete, through paving slabs to the latest innovation: the ProBase recycled interlocking tile system. For a super solid job though we recommend the timber sub frame method. First a hefty outer timber frame is constructed to the exact size of your new garden building using maintenance-free Tanalised timber. This frame is then spanned with a generous number of cross joists and then squared and levelled to suit your ground. It is completely self supporting and the vertical supports which are driven way down into the ground ensure that this system works perfectly even on a slope.

Installation of metal sheds

Metal shed and workshop assembly serviceMetal sheds make a truly cost-effective storage solution and are becoming increasingly popular in these increasingly price-conscious times of late. But they can be time-consuming and frustrating to assemble so an installation service is something well worth considering if you are looking to buy one. We have been offering this service for some time and, whilst it is definitely possible to assemble them yourself, having us come to your site and assemble your new metal storage shed. We can assemble buildings from our StoreChoice, GrandChoice, SafeStore and Trimetals ranges as well as others. Generally steel sheds will come without an integrated floor - being designed to sit directly on top of a concrete base - but, due to the other services offered, we can even construct a sturdy base and floor for your steel building to sit on.

How Do I Build A Suitable Base For My New Garden Shed?

As with any structure, it is essential to provide a firm, level and square base; without which, your building will become unstable and will deteriorate rapidly. Preparations need not be too elaborate and we show the three recommended methods below.

  • ProBase - Far better than concrete, which is expensive and permanent, far better than paving slabs, which are hard to get level with each other, and far better than timber bearers, which can rot when in contact with wet ground. The Probase interlocking garden shed base system is faster, better, easier to build and are recyclable and therefore a Greener option. Further information and how to build on this page.
  • Concrete Base - The traditional method - but needs to be done well. Really only a job for a competent DIYer, or a professional builder.
  • Rows Of Paving Slabs - Simple, yet effective. Also the best solution if the building may need to be moved in future years.
  • Treated Timber Bearers - By far the easiest solution! You simply clear the site in accordance with our guidelines, and the fitters can build straight onto the earth, however the ground must be totally flat and solid.

Whichever method you use, it is important that the end result is above all, firm and square. If you are constructing the base for a building over 12' x 8', a garage, a sectional building, a corner unit, a gazebo, or a building with no floor, we recommend a purpose-built concrete base. Please ask the relevant company for a detailed base plan when they contact you to arrange a suitable delivery date.

Please keep in mind that these base preparations must be concluded before the arrival of our fitter, as they often work alone, and are not able or equipped to undertake groundwork. If laying a concrete base, please also keep in mind the length of time it will take for the concrete to cure. If the fitter arrives and there is not a suitable base, then the building will be left on a self-assembly basis at full invoice price, or a surcharge will be incurred if they have to return another day.

If you are in any doubt, or would like any advice, please telephone, email, or visit our on-line customer support area for further assistance.


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How Do I Prepare For A Building With Bearers ?

PLANNING & PREPARATION
This is the simplest option, however it's not suited to all buildings. If you are constructing the base for a building over 12' x 8', a garage, a sectional building, a corner unit, a gazebo, or a building with no floor, we recommend a purpose-built concrete base.

TOOLS REQUIRED
  • Spade
  • Shovel
  • Tape Measure & String

    CONSTRUCTING THE BASE
    Cut back any infringing trees and bushes. Allow at least 12" (300mm) all around and 36"-48" above the roof of the building. the base must be firm, level, square and designed to suit the floor size of the selected building as detailed above.

    Carefully mark out the exact size of the required shed base, using pegs and string. Check this is square by measuring the diagonals - if the base is square, the diagonal measurements will be equal. Mark 6" all around the outside of this area for the overall size of the 'dig'. remove the setting out strings, but leave the pegs in place for further use. remove all vegetation and clear the topsoil to the depth required.

    Carefully level and compact the ground using a large spirit level - there must be no bumps or imperfections in the level of the base. Finally, please have on-site various pieces of packing in case the fitter needs to pack any of the bearers. These should include house bricks, roof slates or tiles, and paving slabs although this is not part of the erectors job so it is recommended that the bearers are correct to save any problems.

  • If you are in any doubt, or would like any advice, please telephone, email, or visit our on-line customer support area for further assistance.
  • By using this guide, you are exempting 1st Choice Leisure Buildings, it's employees and agents, from any liability which may result in any way.

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    How Do I Build A Slabbed Base ?

    PLANNING & PREPARATION
    Although a far easier (and cheaper) solution than a concrete base, it is still vital that a slab base is correctly constructed. Especially important is the fact that you need to set the rows of slabs at the correct spacings, and running in the correct direction (at right-angles to the runners on the underside of the floor, or the optional timber bearers, if specified.) These rows may be up to 2' apart, however it is important that you have a row where two-piece floor sections abut each other (if appropriate)

    The base must be firm, level, square and designed to suit the floor size of the selected building. When the appropriate company contact you to arrange a delivery date, ask them for a base plan, and make sure that you stick rigidly to this - failure to do so may mean that the building cannot be installed without alterations.

    TOOLS REQUIRED
    • Spade
    • Shovel
    • Hammer
    • Tape Measure & String
    • Large Spirit Level
    • Trowel
    • Rubber Mallet

    LAYING THE SLABS
    Cut back any infringing trees and bushes. Allow at least 12" (300mm) all around and 36"-48" above the roof of the building. carefully mark out the exact size of the required shed base, using pegs and string. check this is square by measuring the diagonals - if the base is square, the diagonal measurements will be equal. remove all turf & vegetation.

    Carefully level and compact the ground, laying a sand/cement dry-mix across the area on which the slabs will sit. Compact this dry-mix and ensure that it is level from front to back, as well as side to side - this will save you a lot of time later.

    Starting in one corner, bed the first slab into position, carefully levelling in all directions using a large spirit level. It is important that you use a large spirit level as this will give a more accurate reading. Take your time here - it is vital that the first slab is absolutely correct - if it's not, then the whole base will be out of true.

    If one of the slabs is too high, and needs realigning, simply lift it and remove a little sand at a time until you arrive at the correct level. Alternatively, gently tap the slab on the top edge of the offending corner with a rubber mallet (or lay a piece of timber on the corner and strike gently with a club hammer) If a slab is too low, lift it and put more dry-mix beneath it until it rises to the correct level.

    Take your time here - it is vital that the first slab is absolutely correct - if it's not, then the whole base will be out of true. When you are happy that the first slab is 100%, lay the second slab in the row tight up against it, following the same guidelines as you did with the first. Ensure that the second slab is 100% in-line with the first by laying the spirit level across the join. When slab number two is in position, continue along the row until you get to the outside edge of the base.

    The next step is to add the remaining rows - in their correct positions. This is basically a re-run of the first row, but it is again vital to ensure that this, and each subsequent, row is perfectly in line with the original. Again this is achieved by laying a large spirit level across the gaps. The slabs must be perfectly level across the whole site in order to spread the load equally and to avoid any subsidence.

    GUIDE INFORMATION

  • This is a guide only. If you do not understand any of it, or are in any doubt, we recommend that you contact a local building contractor. Yellow Pages is an excellent resource for this.
  • If you are in any doubt, or would like any advice, please telephone, email, or visit our on-line customer support area for further assistance.
  • By using this guide, you are exempting 1st Choice Leisure Buildings, it's employees and agents, from any liability which may result in any way.
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    How Do I Build A Concrete Base ?

    OUTLINE
    The most important thing to do when building your new concrete base is to get it right - please remember that concrete is virtually impossible to fix if something goes wrong! If you're not a competent DIYer we'd recommend you seek advice from a local builder. If you are happy to take on this job, take your time, plan the job and read on!

    PLANNING
    The base must be firm, level, square and designed to suit the floor size of the selected building. Contact us to check the exact base size of your chosen model, as these will vary - it doesn't necessarily follow that an 8' x 6' building will have a base size of 96" x 72" - generally it won't.

    When designing the base, it is vital that you take into account whether or not the building has a floor as this will influence the size and design of the base. If it does have a floor, you should add 1" (25mm) to the above dimensions. If it does not have a floor, we will guide you accordingly - please do not use these instructions. We will be happy to provide a detailed base plan for your individual needs in this instance.

    Concrete is a mixture of 'all-in' ballast, Portland cement and water. For this type of base, they are mixed to the ratio of:

  • 1 Part Cement
  • 5 Parts 'All-In' Ballast

    BALLAST
    'All-in' ballast (20mm) is usually sold in 40kg bags at your local builders merchant or DIY superstore. 1.25 bags are needed to produce approx. 1 cubic foot of concrete. Therefore, the formula to calculate the amount of ballast required is as follows:

    Example:
    Shed Base = 8' Long x 6' Wide x 3" deep
    Volume = 8' x 6' x 0.25' = 12 cu ft
    Add 1/3 for compacting = 4 cu ft
    'All-in' ballast required = 16 cu ft
    16 x 1.25 = 20 bags of 20mm 'all-in' ballast

    Quantities for other size bases may be worked out using these figures. The golden rule is to order on the generous size when buying materials. Excavations can seldom be measured accurately.

    CEMENT
    1 bag (50kg) of cement mixed with 'all-in' ballast in the ratio of 1:5 makes:
    24 sq. ft of concrete 3" thick
    or 18 sq. ft of concrete 4" thick
    for 8' x 6' (48 sq. ft)
    3" thick base cement = 2 bags
    for 8' x 6' (48 sq. ft)
    4" thick base cement = 3 bags

    Quantities for other size bases may be worked out using these figures.

    TOOLS REQUIRED
  • Spade
  • Shovel
  • Hammer
  • Saw
  • Tape Measure & String
  • Spirit Level
  • Tri-square
  • Concrete Mixer (for larger jobs)
  • Rammer (to compact concrete whilst laying)
  • Tamping Beam
  • Plastic or Wooden Float

    PREPARATION
    Cut back any infringing trees and bushes. Allow at least 12" (300mm) all around and 36"-48" above the roof of the building. the base must be firm, level, square and designed to suit the floor size of the selected building as detailed above.

    Carefully mark out the exact size of the required shed base, using pegs and string. Check this is square by measuring the diagonals - if the base is square, the diagonal measurements will be equal. Mark 6" all around the outside of this area for the overall size of the 'dig'. remove the setting out strings, but leave the pegs in place for further use. remove all vegetation and clear the topsoil to the depth required. carefully level and compact the ground.

    For ordinary garden sheds, a thickness of 3" (75mm) is sufficient in most situations. on soft clay, or on larger buildings, increase the thickness to 4" (100mm) laid on 2" (50mm) of finely broken and compacted hard-core if required. half the depth of the base (approx.) should be above ground level.

    Replace the setting out strings onto the pegs and check the original measurements. Check the markings are still square by checking the diagonals. These strings are used for positioning the concrete form work. This is made from 2" (50mm) thick timber and should be as wide as the depth of the concrete slab.

    Use a tape measure, spirit-level and try-square to set out the form work accurately. This is nailed onto pegs driven into the ground. These pegs should be sited on the outside of the form work in each corner and every 2' (600mm) It is very important that the pegs do not protrude above the top of the form work as this will make the levelling off of the concrete very difficult. Ensure the top of the form work is carefully checked and is level all around (use a long spirit level)

    MIXING THE CONCRETE
    Try to mix alongside the base site so that the concrete can be placed by shovel, otherwise use a wheelbarrow. Use a plastic bucket (3 gallon) for accurately measuring materials. Use another bucket for measuring water.

    Mix well in the proportion:
  • 1 bucket cement
  • 5 buckets 'all-in' 20mm ballast
  • Add water gradually to the mix until the whole pile is uniform in colour and sufficiently workable to use. Do not make the mix too wet - this weakens the concrete. Note how much water has been used and use the same quantity for each mix. Hire a cement mixer for making large quantities of concrete.

    LAYING THE CONCRETE
    Place a layer of concrete into the form work. Compact this down with a rammer taking particular care to push the concrete into the corners and edges. Tap the sides of the form work with a hammer to help produce a solid edge to the slab. Continue placing layers of concrete into the form work and compacting until full.

    Use the tamping beam with a chopping and sawing motion across the slab; working from one end to the other. This will level off the concrete, leaving it flush with the top of the form work. The concrete should be tamped flat as it is poured. After tamping the concrete should be smoothed out with either a wooden or a plastic float - this allows the batons of the floor to sit evenly.

    Concrete must not be permitted to dry out too quickly or be damaged by frost whilst wet. Cover with plastic sheeting until the concrete is hard and spray with water for several days to allow it to dry out slowly.

    When base is ready, remove the form work and tidy around the base, ready for delivery of your new building. Fill the 6" (150mm) around the edge of your new base with pea shingle to prevent 'splash-back' as rain drips to floor.

    GUIDE INFORMATION
  • This is a guide only. If you do not understand any of it, or are in any doubt, we recommend that you contact a local building contractor. Yellow Pages is an excellent resource for this.
  • If you are in any doubt, or would like any advice, please telephone or visit our on-line customer support area for further assistance.
  • By using this guide, you are exempting 1st Choice Leisure Buildings, it's employees and agents, from any liability which may result in any way.

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    Customer Feedback

     Very helpful when I made enquiries, answering all my questions so that I could make an informed decision, having no knowledge of shed construction previously.  

    Customer Feedback

     I just wanted to say what an absolute pleasure it was to deal with your company. I have overseen the refurbishment of our house which has taken a depressingly long two years.

    Luckily, we haven't had to live in it during that time but once the shed arrived - so promptly and easily - we considered moving in there!  

    Customer Feedback

     Just a note to say that the shed was delivered and erected on Monday as agreed and we are very pleased with it. The customisations - extra opening windows and additional eves height - are great.

    Please pass on our thanks to all concerned for a professional service.