Building a garden office

Discussion in 'Carpenters' Talk' started by dgb99, Apr 30, 2011.

  1. dgb99

    dgb99 New Member

    Hello - I need some help with the design of a timber framed office for my garden. This will be built on the raised concrete base of an old wooden shed measuring about 5 x 3 metres and will be used all year round. Can anyone confirm the following design and point out anything I may have missed?

    Floor - damp proof membrane on top of current concrete, 100mm Kingspan type insulation followed by 18mm chipboard flooring and then final finish (to be decided).

    Walls - built from 90x40mm timber at 600mm centres with noggins. From inside construction will be 10mm Fermacell boards, 80mm Kingspan type insulation between 90mm studs, breathable membrane, horizontal battens for air gap then 19mm vertical cedar cladding. Questions: do the stud walls need fastening to the base? Should I build a short wall of 1 or 2 bricks to sit the stud frame on?

    Roof - built from 120x45mm timber at 600mm centres, joists across 3m span and then rafters to gable at a pitch of 25 degress. Breathable membrane followed by counter battens and cedar shingles. Ceiling made from Fermacell boards with insulation between rafters. Questions: is a 150mm overhang all round suitable? Are 600mm centres suitable for the roof or should they be 400mm?

    I will fit a double glazed door and window. Given the volume of the building (~35m3) and the insulation what would be suitable heating size (electric will be my only option)?

    Many thanks for any help.
     
  2. foxhole

    foxhole New Member

    Seems a little over spec,  my garage is larger and has tiled roof and timbers are smaller than those quoted, cheaper  to get the roof framing made to measure and delivered than to purchase timber and diy.The 600mm centre will be fine.
    Electric only option? you could have gas heating or wood burning stove.
     
  3. big all

    big all Screwfix Select

    are you doing it under permitted development???
     
  4. dgb99

    dgb99 New Member

    It is replacing a current wooden shed which has been there for many years and will be the same size.
     
  5. dgb99

    dgb99 New Member

    What size timbers would you recommend for the roof? Where can I get it made?
     
  6. paulo333

    paulo333 Member

    I built a unit with very similar specs. nearly 30 years ago - still standing, though I did replace the roof and a few joists after some storm/water damage.

    1. I don't think it's over-spec. Not if you want it to last.

    2. Definitely bolts the stud wall to the concrete unless you want it to take off!

    3. I started out with the door and two windows for ventilation but only on the front face. It has Triplewall Polycarbonate Sheeting for skylight and side panels for light but nothing else for ventilation. Make sure you build in through/cross ventilation. In the summer it gets really hot.
     
  7. dgb99

    dgb99 New Member

    Good advice re ventilation. Is it worthwhile building the timber walls on a course or two of bricks?
     
  8. big all

    big all Screwfix Select

    how close to the boundary is it ??
    how high is it ??
    how close to the public highway is it??

    its a new structure so must comply with present planning portals
    http://www.planningportal.gov.uk/permission/house
    http://www .planningportal.gov.uk/permission/house
    remove the space after www

    or if they remove the links google planning portals and click on interactive house
     
  9. dgb99

    dgb99 New Member

    I should do it a bit at a time and it could be a repair :).

    It is ~15 metres from the public highway, ~2.5 metres high and ~1m from the boundary. Neighbours are very happy with it.
     
  10. big all

    big all Screwfix Select

    your ok then within 2m off the boundary it needs to be 2.5m or less
     
  11. dvddvddvd

    dvddvddvd New Member

    Hi im building similar, could you tell me about building near public highway ? My garden is a corner plot with a 6 foot wall running round. On the other side of the wall is a grass area (council owned) and a foot path and road.
    I want to build a timber office 1 mts from the garden wall (to aid maintance, with a floor area of 20mts square (4 X 5). I thought if its less than 2.5 mts high (flat roof) near boundry it was ok ? thanks
     
  12. big all

    big all Screwfix Select

    boundarys from neibours are ok but you need to check as any area open to the public foot path or roadway do count
    it dosnt mean you cant it means you need to apply for permission iff its too close
     
  13. dgb99

    dgb99 New Member

    Any more thoughts on my design of base or roof? Thanks:)
     
  14. big all

    big all Screwfix Select

    my shed is 10x12ft with around 30 degrees all structures are made from 3x2" at 2ft centres except the roof thats anywhere between 2 and 4 ft
    *

    Message was edited by: Screwfix Moderator
     
  15. dgb99

    dgb99 New Member

    Any more thoughts on my design of base or roof? Thanks:)
     

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