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Good Evening, I am building a new outbuilding in my back garden. I am trying to figure out what the best electric heating solution (CH + HW) would be and I would like to ask you for your opinions here. The outbuilding will contain an office, a gym and a small bathroom with a steam shower unit and a sink as per the plan below. It will be used throughout the year on a pretty much daily basis. I initially thought about using electric heating mats for my UFH and a small boiler for my hot water needs but now I think there may be a better, more cost effective solution. I have seen a number of threads talking about ASHP, Ampec flow boilers and Willis heaters. It made me think about fitting a wet underfloor heating system and using one of the solutions but honestly speaking I am not sure what would be best as my knowledge and experience is limited. I would be very grateful for any advice. Martin

Hi All, Just got planning permission granted for two outbuildings in the garden and starting to figure things out. Been reading this forum for a few months now and it has already been very helpful in answering my many questions. I know I will have many more questions so this certainly wont be my last post! The plan is to build both at the same time. Here is a brief rundown of the plan so far… 1 x Hobbies room @ 10x5M approx. 1 x Office/Studio @ 11x8M approx. Rainwater collection (eventually house will connect to it when it gets refurbished after this project) New Septic tank (eventually house will connect to it when it gets refurbished after this project) Grounds/Floor: Unknown as I need a ground investigation due to soil and trees but I suspect some sort of pile. Walls: Hopefully ICF and currently looking at Isotex or Durisol. Office first floor: Looking at Thermohouse floor. Roof: Looking at Thermohouse roof. Finished with slate. Finish: Larch, or similar, vertical cladding. Budget: no doubt not enough but I plan to do most of the work myself…apart from the GW. Plan to start in Autumn 2020 or Spring 2021. I also have two planning conditions, tree roots and archaeological watch just to add to the excitement. Closest trees (Sycamore) are to the north of the hobbies room in the neighbours garden which are about 3M away from proposed wall of hobbies room. Like most things, all subject to change! Currently getting quotes from many people and trying to find my way through it all ☺ Pictures attached that will give more of an idea.

Inspired by this thread from @mrfish, Can we have a thought experiment as to just what it costs to build an insulated garden office with reasonable facilites? (Also because I still need something like this). I wamt to think through cost-effective options and see if I have not though about any aspects. My £3k number is because more-or-less this is what it costs to buy a secondhand insulated, wired, site office of this size and spend £400 shipping it in. My specification is for: 1 - 8 x 12 ft insulated garden room, capable of being practically used all year round. 2 - 2 x double electrical socket, water, lighting and drainage. 3 - Building base. 4 - I want to be able to dismantle it and rebuild (eg every few years). This is perhaps a personal requiremnt for me. I am excluding items difficult to compare: 1 - Labour to build and fit out, because most of us could do this ourselves. 2 - Supply connections, as they could all be different depending on the circumstances. Ferdinand

I'm building one! Previous thread for reference: The project is an 8x12 garden building to be used as a standalone utility room for a small house. The ground conditions are solid - outdoor loo removed decades ago, and used as a parking space, then various bits of limestone and concrete put on there over the subsequent 3-4 decades. I personally had two lorry loads of stone put on that side. Approx half is over an existing estd. 100mm concrete slab. Elements (and budget): 1 - Basic building. A SiPs kit from Simply SIPS, which gives an insulated 8x12' kiosk faced with OSB3, with a 5ft wide doorway for £1335. 97mm SiPs with U value of 0.3. Thicker panels not required as it is not designed for full day occupation in winter. Need to fetch it from Spalding - allow £100. 2 - Doorway. I will pay between about £600 and £800 for a custom made and fitted PVCu door and glass side panel to a pair of French doors for that gap, including locks and fitting, with a U-value of 1.5 or so. 3 - Base. Either 2" concrete slabs - £1 per square foot = £100, or 2" concrete slabs on Adjustable Support Pads which will allow me to adjust things after it is built if anything moves by changing the heights. 25 support pads ~ £100. 4 - Rainscreen Cladding. Box section plastisol coated corrugated at £10 per sqm including overlaps. Area required for walls ~ 25sqm => £250. Trims and special screws and things add £100 => £350. 5 - If I choose to batten out the corrugated for air circulation then approx 50 CLS length at £1.80 each => £90 plus £10 for bits and pieces ~ £100. Or 125m of roofing lath 30p per metre ~ £50. May be a better option as this is tanalised. 6 - Roof. It comes with a 1:40 fall towards the back. EDPM membrane. Say £150 including adhesive and trims etc. 7 - Captain Belt 'n' Braces may suggest a breathable membrane round the walls under the battens. 25sqm => not very much to buy. So for the groundworks and the building we are now at £2750 or so. In addition and not included: 8 - Electricity supply requiring FCU and switch in house, then about 2m of armoured cable, garage CU for lights, a ring main to power 3/4 double sockets, a small water heater, potentially a small fan heater for short periods, and a ventilation fan. Need a real electrician as it is for a rented house. 9 - A path down the side. 10 - A privacy fence across the front. 11 - 2 men approx 2 days to build it. 12 - I hope to build it such that it can be easily dismantled and relocated. The only fly I have in the ointment is, I think, that I need to watch the height carefully wrt permitted development. Ferdinand