Garden office buildings
Discussion
Morning all, I'm looking into the possibility of getting a garden office/studio type building at the end of a garden at a house I'm considering buying. Aware that I might need planning permission but just want to scope out possible costs of the actual building at this stage, see if it's a goer.
I would like it to be about 5/6m wide, maybe 3m deep. To include an office room with space for sofa bed, a small kitchenette and a shower room with toilet. So obviously needs plumbing, waste drainage, electrics. Want it to be insulated and heated for winter use, either off the mains electricity or maybe an aircon/heater unit from a heat pump.
Anyone here done similar? What sort of sum did it end up costing if so? I want a turnkey build, I don't want to do any work myself because I'm utterly incapable and don't have the time or energy. Garden is about 40 feet long, so that's the max distance from the house and existing utilities.
It's really hard to get any proper idea from company website, it's all obfuscated and obscure, I suppose deliberately so that you ring them and they can start selling it to you.
Any recommended companies or suppliers in the west London/east Thames Valley area?
I would like it to be about 5/6m wide, maybe 3m deep. To include an office room with space for sofa bed, a small kitchenette and a shower room with toilet. So obviously needs plumbing, waste drainage, electrics. Want it to be insulated and heated for winter use, either off the mains electricity or maybe an aircon/heater unit from a heat pump.
Anyone here done similar? What sort of sum did it end up costing if so? I want a turnkey build, I don't want to do any work myself because I'm utterly incapable and don't have the time or energy. Garden is about 40 feet long, so that's the max distance from the house and existing utilities.
It's really hard to get any proper idea from company website, it's all obfuscated and obscure, I suppose deliberately so that you ring them and they can start selling it to you.
Any recommended companies or suppliers in the west London/east Thames Valley area?
Ok, thanks. That's all important stuff and I'm aware that would need to be investigated with the local authority, as mentioned in my original post. I am not ignoring it and will not ignore it. That'll be the next stage of my feasibility investigations.
But for the purposes of this thread, I'd like to get anyone's real world experiences of supply and build costs of such a thing if possible.
But for the purposes of this thread, I'd like to get anyone's real world experiences of supply and build costs of such a thing if possible.
Edited by 127Sport on Thursday 22 October 13:01
6 x 3 = 18m. At £2k per sq m (and that's being conservative) - you're already at £36k plus 10% for contingency makes it ~£40k.
Given that you're having all the services put in - electrics, plumbing, shower room, kitchenette.. I'd be very surprised if you can do it for under that amount. £50-£55k is a more reasonable figure.
Your primary fight is going to be with your LPA - getting permission for effectively a granny flat/self contained unit is not the easiest thing in the world and you need to demonstrate that the outbuilding is going to be subservient to the primary house.
Given that you're having all the services put in - electrics, plumbing, shower room, kitchenette.. I'd be very surprised if you can do it for under that amount. £50-£55k is a more reasonable figure.
Your primary fight is going to be with your LPA - getting permission for effectively a granny flat/self contained unit is not the easiest thing in the world and you need to demonstrate that the outbuilding is going to be subservient to the primary house.
Wowee. Hmm. Sounds a whole lot more expense than I was thinking - I thought about £25k as I've seen some places listing building kits on sale at about £10k, obviously not including construction/installation/finish.
£2k per square metre, huh? Hmm.
Maybe I'll pull back on the plumbing ambitions. I had wanted to be able to have guests sleep there occasionally and not need to do a midnight flit to the house for a pee.
Even so, tens of thousands on a glorified shed seems a bit rich.
£2k per square metre, huh? Hmm.
Maybe I'll pull back on the plumbing ambitions. I had wanted to be able to have guests sleep there occasionally and not need to do a midnight flit to the house for a pee.
Even so, tens of thousands on a glorified shed seems a bit rich.
Edited by 127Sport on Thursday 22 October 13:07
My 6m x 4m cabin with 65mm timber was ~22k including a/c, rubber roof tiles and extra sockets. That includes a separate bathroom into which we put a portable chemical toilet and sink (ie no plumbing for the reason mentioned).
This was in 2020 in Surrey.
I think garden offices (with extra insulation and laminate flooring) command a premium over cabins, so you could look into those. HTH.
This was in 2020 in Surrey.
I think garden offices (with extra insulation and laminate flooring) command a premium over cabins, so you could look into those. HTH.
127Sport said:
Wowee. Hmm. Sounds a whole lot more expense than I was thinking - I thought about £25k as I've seen some places listing building kits on sale at about £10k, obviously not including construction/installation/finish.
£2k per square metre, huh? Hmm.
The other thing to consider will be (as this is PH) residual value/ depreciation - a loft conversion will add value to your house, a garden building may make it more marketable but far less likely to add value. That’s a conversation to have with a good local estate agent. In the long term your £100,000 loft conversion will likely cost less than a £50,000 garden room. But different markets work in different ways so speaking to an EA will let you know how yours operates. £2k per square metre, huh? Hmm.
FarmyardPants said:
My 6m x 4m cabin with 65mm timber was ~22k including a/c, rubber roof tiles and extra sockets. That includes a separate bathroom into which we put a portable chemical toilet and sink (ie no plumbing for the reason mentioned).
This was in 2020 in Surrey.
I think garden offices (with extra insulation and laminate flooring) command a premium over cabins, so you could look into those. HTH.
Thanks, that sounds more reasonable. Hadn't thought of a chemical toilet. Good idea for occasional use.This was in 2020 in Surrey.
I think garden offices (with extra insulation and laminate flooring) command a premium over cabins, so you could look into those. HTH.
When you say cabin, can you give me a visual idea of what you mean please? How well insulated is yours and would it allow someone to sleep in it during the winter, without having a heater raging away permanently?
JQ said:
127Sport said:
Wowee. Hmm. Sounds a whole lot more expense than I was thinking - I thought about £25k as I've seen some places listing building kits on sale at about £10k, obviously not including construction/installation/finish.
£2k per square metre, huh? Hmm.
The other thing to consider will be (as this is PH) residual value/ depreciation - a loft conversion will add value to your house, a garden building may make it more marketable but far less likely to add value. That s a conversation to have with a good local estate agent. In the long term your £100,000 loft conversion will likely cost less than a £50,000 garden room. But different markets work in different ways so speaking to an EA will let you know how yours operates. £2k per square metre, huh? Hmm.
A few observations from my side (currently going through a new build):
1. 2020 Prices are not a useful barometer for prices in 2026. Materials are up as energy prices have driven up unit economics, and the cheap labour has departed post Brexit/COVID - so they're both significantly higher.
2. Removing the plumbing option will make it far simpler and give you a better chance of getting planning approval.
3. Comparing the online kit cost versus your intent of having it completely done for you is what is going to shift the needle. You obviously save on a significant chunk of the labour if its you doing the work.
1. 2020 Prices are not a useful barometer for prices in 2026. Materials are up as energy prices have driven up unit economics, and the cheap labour has departed post Brexit/COVID - so they're both significantly higher.
2. Removing the plumbing option will make it far simpler and give you a better chance of getting planning approval.
3. Comparing the online kit cost versus your intent of having it completely done for you is what is going to shift the needle. You obviously save on a significant chunk of the labour if its you doing the work.
OttoMattik said:
A few observations from my side (currently going through a new build):
1. 2020 Prices are not a useful barometer for prices in 2026. Materials are up as energy prices have driven up unit economics, and the cheap labour has departed post Brexit/COVID - so they're both significantly higher.
2. Removing the plumbing option will make it far simpler and give you a better chance of getting planning approval.
3. Comparing the online kit cost versus your intent of having it completely done for you is what is going to shift the needle. You obviously save on a significant chunk of the labour if its you doing the work.
Yes, that s why I included the year as well as the cost.1. 2020 Prices are not a useful barometer for prices in 2026. Materials are up as energy prices have driven up unit economics, and the cheap labour has departed post Brexit/COVID - so they're both significantly higher.
2. Removing the plumbing option will make it far simpler and give you a better chance of getting planning approval.
3. Comparing the online kit cost versus your intent of having it completely done for you is what is going to shift the needle. You obviously save on a significant chunk of the labour if its you doing the work.
The cost I quoted was fully installed. Took 3 days. It sits on an array of plastic supports that are sunk into the ground until they hit something hard/supportive enough. It’s a great space and we are really happy with it. We treated the outside ourselves with their recommended coatings.
Edited by FarmyardPants on Thursday 22 October 15:45
127Sport said:
Thanks, that sounds more reasonable. Hadn't thought of a chemical toilet. Good idea for occasional use.
When you say cabin, can you give me a visual idea of what you mean please? How well insulated is yours and would it allow someone to sleep in it during the winter, without having a heater raging away permanently?
It s basically a rectangular cabin with one corner allocated to a small separate room with its own door. Double doors in the centre of the length, flanked by windows, and windows on each width. Double glazed.When you say cabin, can you give me a visual idea of what you mean please? How well insulated is yours and would it allow someone to sleep in it during the winter, without having a heater raging away permanently?
There is insulation under the floor, but not the roof. The a/c acts as an efficient heater, I would not describe it as raging away
. We use the heat option more than we use the a/c to cool, although this summer it proved very handy. People sleep in there occasionally on the sofa bed.Edited by FarmyardPants on Thursday 22 October 18:28
Ooo, finally, I've found a company website which is actually helpful. Under £22k for a non-plumbed one, including installation, electrics, and foundations sounds reasonable (company: Green Retreats).
I wonder if one could put a "pod" type thing like you'd find in a motorhome in one of these, with a toilet, shower and sink (obviously not plumbed to mains water or drainage, but done from a water tank and chemical waste capture). Bit Heath Robinson but only for use a couple of times a year, so not really a big deal.
Website says it's insulated in walls, floor and roof.
I wonder if one could put a "pod" type thing like you'd find in a motorhome in one of these, with a toilet, shower and sink (obviously not plumbed to mains water or drainage, but done from a water tank and chemical waste capture). Bit Heath Robinson but only for use a couple of times a year, so not really a big deal.
Website says it's insulated in walls, floor and roof.
Three elements to consider (which you already are);
Planning Permission
Depends... but Class E of the GPDO allows detached outbuildings for purposes incidental to the enjoyment of the dwellinghouse. There are Appeal decisions supporting the provision of an office, toilet/shower, kitchenette and sofa for relaxation.
However, the moment you introduce sleeping accommodation you are potentially outside Class E and may require planning permission. The intended use is the important distinction, rather than simply having a sofa bed.
Building Regulations
If the building is no more than 30m² and contains no sleeping accommodation, it can be exempt from Building Regulations approval. The exemption applies where it is detached, single-storey, contains no sleeping accommodation and is at least 1m from the boundary (or constructed substantially from non-combustible materials).
So an office with ancillary toilet/shower and kitchenette could qualify. However, electrical installations, plumbing and drainage may still require compliance or certification.
Costs
Wholly dependent upon specification... but if you want something with meaningful insulation, I would consider ground screw foundations, an insulated timber floor and SIPs construction, subject to ground conditions. Obviously, if you're not DIY inclined, you'll be paying someone else to construct it, and they'll want to make a profit.
Planning Permission
Depends... but Class E of the GPDO allows detached outbuildings for purposes incidental to the enjoyment of the dwellinghouse. There are Appeal decisions supporting the provision of an office, toilet/shower, kitchenette and sofa for relaxation.
However, the moment you introduce sleeping accommodation you are potentially outside Class E and may require planning permission. The intended use is the important distinction, rather than simply having a sofa bed.
Building Regulations
If the building is no more than 30m² and contains no sleeping accommodation, it can be exempt from Building Regulations approval. The exemption applies where it is detached, single-storey, contains no sleeping accommodation and is at least 1m from the boundary (or constructed substantially from non-combustible materials).
So an office with ancillary toilet/shower and kitchenette could qualify. However, electrical installations, plumbing and drainage may still require compliance or certification.
Costs
Wholly dependent upon specification... but if you want something with meaningful insulation, I would consider ground screw foundations, an insulated timber floor and SIPs construction, subject to ground conditions. Obviously, if you're not DIY inclined, you'll be paying someone else to construct it, and they'll want to make a profit.
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