Garden Office

Discussion in 'Builders' Talk' started by Try and DIY, Jan 15, 2019.

  1. Try and DIY

    Try and DIY New Member

    I am in the drawing stages for making a garden office.

    Was looking at the online log cabins but feel it will be best to build from scratch since I want to use this office daily with insulation and electrics etc.

    My plan is a 2x4 stud frame, moisture wrapped, then OSB which is rendered. Insulateb betweenthe 2x4 and plasterboard inside. Would OSB handle the lovely British weather? Would a cement board like the tiling ones be better?

    Any thoughts would be very grateful.
     
  2. goldenboy

    goldenboy Super Member

    I shiplapped mine. And used Garden Shades to finish it.

    Lasted 12 years while I lived there.

    Sold the house recently and it still looked brand new
     
  3. Hans_25

    Hans_25 Screwfix Select

    Take a look at interlocking log cabins, typically 44mm thick. No insulation required for the walls, can fit say 50mm PIR to [warm] roof and floor between joists.

    What size are you thinking?
     
  4. Try and DIY

    Try and DIY New Member

    Looking as big as I can without building regs, 5x6m, 2.5m high. Will do flat roof and have it done by a roofing. Three layer felt I think is the term.

    Were the 44mm warm enough?
     
  5. Try and DIY

    Try and DIY New Member

    Thanks goldenboy. Did you insulate it?
     
  6. Hans_25

    Hans_25 Screwfix Select

  7. Try and DIY

    Try and DIY New Member

    It's either I buy the kit from a supplier or just make something bespoke. Was thinking of a rendered stud frame so it looks more solid and built to last. Most of the building will be hidden by fences at the end of the garden. All of the lovely wood will be hidden and not to show.

    www.tuin.co.uk/flow-log-cabin.html

    I like this one and with the sale it's a good price. But worry about the wood moving over time etc.
     
  8. Wayners

    Wayners Screwfix Select

    Make it air tight with plastic and some cheap insulation in walls and it will be warm. I put Kingspan 25mm in ceiling and felt cool to touch on the sunniest days. It's the heat in summer that's more of a problem than the cold. The inside was just osb wood sheets painted and the structure I built myself. Bought some of the materials second hand Inc double glazed window. Mice can nest in rockwall though
     
  9. Try and DIY

    Try and DIY New Member

    Did you have to do air gaps, moisture wrapped etc? It's really just a fancy shed but I need it to be warm and weatherproof so I can sit out there working on the computer. Painting OSB as internal walls is a good idea, thanks.
     
  10. Wayners

    Wayners Screwfix Select

    No air gaps as such. Vent in window was already there. Run phone cable and power cable underground. I'd use that cheap polystyrene 25mm if doing again because of mice. If you cut polystyrene tidy and run mastic around it will be air tight enough. Just wood floor with old carpet
     
  11. Try and DIY

    Try and DIY New Member

    Didn't about mice. That would keep the wife away ha ha ha
     
  12. Mr Rusty

    Mr Rusty Screwfix Select

    I'm in the planning stage for a similar building. My plan is to use a suspended wooden floor on foundation pads, and build the building using SIPs https://www.sipsdirect.co.uk/ . Hardie plank clad exterior. Loads of construction details available from the SIP suppliers. When you add up the separate components - framing, insulation, cladding, SIPs make a lot of sense.
     
  13. VladTheLad

    VladTheLad New Member

    Go to youtube and search for "Garden room Halifax" to see my recent garden room project which I built just on my own. Previously I used to work for one UK garden office manufacturing company which is relatively quite popular as every week we installed around 3-4 bespoke buildings nationwide (10,000£ - 30,000£ per build), but unfortunately (or fortunately) I was sacked due to my passion for inovation and for a strive to do things right which seems companies like the one I used to work for simply do not need, as they get constant flow of customers who pay for their product.... who cares that product quality does not meet price people pay for it.

    My advice would be to avoid bespoke garden room companies as per your initial post I can understand you are capable of building garden office yourself, so with some reasearch and own thinking you will be able to build really something unique and most important you will know for sure how good your building is insulated and so on...

    If you plan to use it as an office then without a doubt it should be fully insulated (floor, walls, ceiling) and I also would highly recommend to go extra mile and invest around 300£ to have underloor heating too, unless you won't take shoes/warm socks off while working in your cabin. Don't get me wrong, it would be still warm enough to stay in fully insulated cabin without floor heating during cold weather as long as you use heater, but with underfloor heating it would be different ball game. This is something that not really meant to be done after everything is finished, so if you can afford it - do it.

    As insulating material I would highly recommend to use PIR boards as it is more likely currently most efficient insulation material available. Using PIR boards with both sides foiled would allow to reflect heat in summer from outside to keep room cool and same principle would allow to keep your garden office warm in the winter time.

    For base framing I would use tanalised timber (4x2 with 40cm joist centres or 6x2 with 60cm centres) and sit base timber structure on composite legs (each leg would be in a small hole filled with around 10kg of Postcrete - Ready to Use Concrete). On top of that I would put damp-proof plastic membrane and lay standard moisture resistant tongue&groove floorboards (For a best result very important to use D4 glue). At the very last stage of whole building process on the floor I would lay underfloor insulation and laminate flooring with MDF primed skirting boards going round.

    Walls I would build from 4x2 CLS with 60cm upright centres and for a big door lintel I would use Kerto LVL beam (Laminated veneer lumber) which is in many applications stronger then a steel RSJ beam and most important its easy to work with as it's actually wood.

    Normally for roof joists I would use tanalised timber (4x2 with 40cm joist centres or 6x2 with 60cm centres), but in your case 5m span in distance would need to have I-joists (I would use I-joists probably on every garden room with 4m+ span in-depth). On top of joists as an example would go tanalised 2x2 cut from full to 0 on an angle in a distance, to make small slope. On top of that I would install 18mm OSB sheets and EPDM rubber membrane. As I put insulation inside, my roof system would be classed as cold flat roof, but it does not mean that temperature in the building will be lower when "warm flat roof system" is used.

    Building walls I would wrap outside with breathable membrane and put some 2x1 tanalised battens horizontally which would allow to clad building by using prefered tongue&groove materials such as log lap, expensive Canadian Western Red Cedar or more affordable Softwood Matchboard which can be treated to achieve any desired finish.

    For interior I would use MDF boards such as ready primed Bead&Butt MDF Boards for walls and standard moisture resistant mdf boards for ceiling (to cover board joints simpliest way would be to use think wood ceiling strips).
    MDF also would be used to make window/door reveals. On ceiling and to trim around windows/doors also would use bull nose mdf architrave.

    For exterior finish I would use standard fascia and vented soffit which you could find in most plastics merchants.

    For electrics you will need somebody to bring supply from your house and obviously wire everything safely inside garden office per your requirements.

    Regarding insulation.. Easiest way is to cut PIR sheets to size to fit each partion (floor, walls, ceiling). Also would recommend to use vapour barrier on ceiling.

    This is just brief info from me to give maybe something to think about.... If you will need any advice on something specific, feel free to ask here or through contact details I left in my youtube video.
     
    Hans_25, Peter208 and Wayners like this.
  14. Peter208

    Peter208 Active Member

    I'm not thinking of one myself but enjoyed reading Vladthelad write up.
     
  15. Try and DIY

    Try and DIY New Member

    Thank you very much. That is very detailed and will watch the video later on. I'll price everything up with the timber merchants and double glazing guys and see what I get price wise.
     
  16. Try and DIY

    Try and DIY New Member

    What's your youtube name?
     
  17. VladTheLad

    VladTheLad New Member

    Cooperatism Youtube

    From my experience dealing with some merchants I can tell that when I was walking in their stores for a quote dressed smart they priced me higher than I was walking dressed as a trades person. For them you could look as a one time customer or potential regular customer who looks like he knows current market prices...

    Worth also checking ebay or maybe other places such as FaceBook Marketplace for used UPVC doors/windows or you migh be lucky to grab new set such as mis measured one like I did for customer in Halifax. Someone was selling mis measured new Warmcore Aluminium Bi-Fold doors for 750£ which would cost 2000£+ by going and ordering them per own request. On top of that from the same seller I ordered full hight&wide UPVC window with top opener for 250£...

    Worth to mention that trending Anthracite grey colour on UPVC windows/doors typically a bit more expensive than white one... But on my own building I would definitly use Anthracite grey windows/door/fascia/soffit - this would make building look more contemporary.
     
  18. Try and DIY

    Try and DIY New Member

    It's funny how you get better service wearing clothes with cement and paint blobs.

    So your layers for the walls are: cladding, 2x1 for air gap, breathable membrane, then 4x2 with PIR boards between. Then MDF for the internal walls. Use a plastic fascia at the top with a rubber roof over 18mm OSB. I'll put PIR between the roof and floor joists. I'm going over a level concrete slab so will build up from treated timber, the first level, on the concrete with a sheet of DPM between. Was going to glue the DPM to the outside edges of the first level of treated wood. Does that make sense? Will watch your video now
     
  19. rogerk101

    rogerk101 Screwfix Select

    Freecycle and Freegle are both excellent places to get used windows and doors. Most people around here (Oxfordshire) welcome having someone take unwanted windows and doors that become useless to them after they have had an extension done ... saves them having to pay to get rid of them at the dump, and saves them ending up in landfill, and saves you a fair bit of money.
     
    VladTheLad likes this.
  20. VladTheLad

    VladTheLad New Member

    Yes, that's correct order of wall layout which is used in most fully insulated garden rooms, same as in cabin from my video. Probably most ideal set up would be to have full sheets of PIR insulation laid inside on uprights, bottom of roof joists and top of the floor boards then all joints sealed with appropriate tape. This would not only make most efficient insulation system, but also would serve as a complete vapor barrier (as far as I know and understand, foiled PIR insulation have characteristics to server as a vapour barrier). Regular method putting PIR insulation in partitions definitely is quite good enough, but most important it is the easiest way to work around.

    For example for your walls when you board room inside, you simply place MDF headbutt board and pin it with 2nd fix nail gun normally to 3 joists (left/middle/right). Uprights position must match board size which is normally 244cm by 122cm (you would need to cut off top to match your ceiling height), so upright centers should be 61cm (neighboring board edges matching each other in middle of upright). And 2nd fix pins are tiny enough to be even simply covered with standard roller while painting your garden room. If you select this method I would also highly recommend applying sealant adhesive on all your uprights such as Soundal Fix All Crystal Adhesive, this would eliminate any bouncing from your wall boards.

    With the ceiling same story of simplicity. When PIR insulation placed between roof joists, you simply screw your MDF 18mm board to 3 or 4 roof joists (depending on your joist centers), majority of screws and all board joints will be covered with ceiling strip. Architrave would cover edge screws plus obviously joint between ceiling and walls. Use filler for some screw holes and calking to bead around architrave, skirting boards and in corners to hide/smooth corner joints, literally where you see some gaps... If for some reason boards in corners ended up to have massive gaps, then same wood ceiling strip can be used to cover it (in this case you would put it probably in all corners to make it look right, otherwise if even other corners are perfect, it might look odd that only one corner have ceiling strip).

    Regarding your idea with DPM membrane — this makes sense to me, but not sure how actually it would affect base timber as virtually there won't be any ventilation for timber not to sweat and breath. Only way to find out how good method is, would be building your garden office using this method or to hear someone who did exactly what you are planing to do... At the of the day I have sympathy for your idea.
     

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