Extension / Garden Room

AdamBloke

Hello all - I have read a few posts here and would love to get some advice. I'll try to be as detailed as possible to save you all time in the long run.
We would like to add a single room, single storey extension to our house (family has grown to the point that we need it now). House is semi detached and size isn't an issue in terms of area covered or height restriction etc as the garden is of a fair size. I have discussed at length with local planning who have been very helpful in telling me what's not possible and what would be frowned upon were I to make the application for certain ideas.
The crux of our problem is a beautiful tree on public land about 1m outside our fence and 2-3m from the corner of the viable plot. We love the tree for it's shade and character and so don't want to affect it anyway, but it does mean that without super deep foundations a 4x3m extension of the standard brick & block type is a no go. The second issue is that this is not an expensive house or area and so throwing a considerable amount into the extension would not be sensible budget-wise or as an investment. I suspect a 30 grand extension would probably add at most 20 grand to the house price. We're not doing this as an investment (it's for us, so profit isn't so important) but it would be nice not to spend considerably more than it's worth in this area (ex-council houses on outskirts of town).
I'm not a cheapskate and believe in making something beautiful, in line with planning (hence paying for the planning consultancy and exchanging emails with them). I also value the importance of building controls and doing things correctly for my family's sake.
We have, over the course of our discussions had to compromise our aspirations greatly for various reasons. Chief amongst them is that without trench foundations brick walls aren't going to happen, and without them we won't match current house materials. So permitted dev (if within size) isn't going to happen and planning officer says most likely, larch/cedar clad extension application would be refused, which I do understand. Conservatory isn't an option since it's on the NNW elevation (and anyway, we would like a year-round space). I have been very happy with the guidance the planning officer has given in terms of what's not allowed and why - and find it all valid and fair. But he doesn't tend to point me towards ideas that we CAN actually do. Currently we are looking at simply building a garden room on that plot as it is against the side wall of the house with no windows/doors. That garden room would be permitted development and we could use simple pad foundations and access externally. The only drawback is that it is in winter that we feel the need for more family space (when we're all stuck indoors) and external access would somewhat limit the use of the extra space created during the winter (a quick run of 2m from back french doors to garden room door in wind & rain doesn't appeal hugely).
The reason I'm posting here is to ask if anyone can suggest any other idea I might ask my planning officer about before we settle on this plan. He also said brick slips would likely be frowned upon too. I don't want to get around planning, I wish to do everything properly (and intend to build to building standards even when not required), but I don't really know what other options might be available, so thought that some experienced developers such as yourselves might be able to suggest something else.
One last question - if we do follow the garden room idea, it would be far easier to build it up against the house. I have read extensively and have only found the difference between class E & A here (page 41 of Permitted rights for house holders - technical guide) - "Buildings which are attached to the house are not permitted under Class E (they would be subject to the rules in Class A)." Which is fair, but cannot get a firm answer as to how 'attached' is defined. Are we talking internally connected through doors? Thermally connected? Structurally connected? Attached via fixings? Simply touching / in contact with?... If I could build up against the house I wouldn't need to clad that side of the garden room (as I would somehow have to if there was a 5cm gap) and I could simply use flashing to stop any water ingress. Also having the garden room butted up against the house wall would mean less exposed surface area and so both the main house and garden room would be more thermally efficient which would make sense to me. If a gap is required then fair enough - but I also cannot find any mention anywhere of how big that gap is required to be. I have asked the planning officer this, but seem to be getting a bit of an unclear answer. He also made the mistake of initially saying eaves overhang was counted in 3m extension and then changed that advice as 3m is measured from base of wall, so I'm not super confident that he is across all the details with some aspects.
Thank you for sticking with this long post - if anyone needs any more info I'll be happy to provide & thanks in advance for any suggestions you can offer

FreeBear

There are other options for foundations that don't involve digging super deep trenches. Piling is one option if you can get a rig on to site - A structural engineer would be able to advise as to what sort of foundations would be most suitable.

Doozergirl

This post is a bit long and full of misinformation that I find it difficult to address all of it, but any extension is going to need 'proper' foundations, whether that be trench or otherwise.  It doesn't matter what your extension is built of - masonry or timber.    My house is timber but has 2.4 metre deep foundations because of trees. 

Building a 'garden room' without proper foundations is a terrible idea.  It isn't so much about the weight of the building, certainly with simple housebuilding.  The purpose of the foundation is to hit solid ground that isn't subject to movement - because the ground always moves, particularly if it's next to a tree!   You build anything without adequate foundations next to a significant tree and it is highly likely to be affected, almost guaranteed with certain soil types.  The ground will expand and contract as the tree adapts to find water when it is scarce, and swell when it is wet or when the tree is removed and no longer takes the resource. All buildings move.   Any building that isn't designed to withstand that is going to move more.  

To answer the question about being 'attached' to the house, something like a conservatory built to avoid building regulations needs to have external quality doors separating it from the house and should not be on the main central heating run of a house.  

This website deals with Permitted Development rights in great detail and used to have a "Top 10" loopholes - one of which is the detached outbuild, barely detached from the house, but it seems to have disappeared.   

Planning officers are deliberately non-commital about virtually everything, but I'm not sure about some of the conversations you've been having.  The brick slip point might be a red herring when it comes to meeting building regs, but brick slips are actual bricks, so if an extension looks similar to other houses, they can't dictate to that level what materials are used if your PD rights are all intact.   

davilown

As @Doozergirl says, if you're going to do it, do it properly.  Having had a conservatory on a South facing wall, they're too hot or too cold.  A garden room is likely to be the same.  If it's an investment in your own living, and you're not going to move, then spend the £30k as you will most likely regret any other course of action.
Do it once and once only

Edit:  Oh and how much would it cost you to move somewhere that had the space?

Doozergirl

We can't see your house, but some creative planning is required beyond these rather confusing and restricted conversations between you and the planning officer.  

An architect would be a good idea.  It could be designed to avoid the extra depth by building partly away from it, or space could be found inside the house even. 

What is it that you need from your house now?    The conversation has to start from what can be done by someone with knowledge of actually doing it 😉

AdamBloke

Wow - you guys are great! I wish I had come here earlier... in terms of the 'full of misinformation' comment Doozergirl - I'm sure you are absolutely correct - I am a bit confused by the conversations I've been having with the planning officer and some of that misinformation is on me, I hold my hands up - trying to learn all this stuff, but I am a bit of a novice.
Saying that - to go through a few points... I will look into the possibility of pile foundations, may well be the answer to getting an actual brick extension rather than a detached outbuilding.
Doozergirl & davilown - lot's of good points - to go a bit front to back - what we want from this is one extra slightly versatile space (possibly office, possibly play room) with a link to the back garden. We are okay for bedrooms but the house is a bit top-heavy and we have 2 growing kids. I could move my office out of the current house or keep it where it is create a more public garden linked space (which would be preferable).
In terms of plot & architect - I did actually ask an architect friend of mine to pop over and we agreed that this plot is really our only option given the constraints (garden dimensions, boundaries, light into existing house etc). He sketched out the original extension scheme plan, but it was since then that I've hit the issues with foundations, then cladding solution, which bought us to planning issues (not PD if different materials).
That then took us on to detaching it so it could just be a garden room. We saw a lot of those garden office/annex things online and thought we could build something like that as a kid's hangout - especially as they get older and want somewhere for them and their friends to chill away from us. Looking at all those advertised they were built on pad foundations (even the high quality expensive ones), so I thought that we could do something similar but with much better insulation levels and build quality than most of those outfits offer. So... do most of those things fall apart after some time as the ground moves or is it that the pads need adjusting or they end up on a slant?
We had the discussion about a conservatory, but agreed that an oven/icebox for most of the year just didn't make sense. We'd like something with say 25% wall glazing (sliding doors) and a solid insulated roof.
We thought about moving, but for what we have we're really very happy here - nice community, kids are settled, lovely garden and house that we've spent time doing up. Only drawback is this lack of a single extra living space especially for the kids.
We have a limited budget and could just about manage a standard build but the costs were being skewed more and more towards the foundations and leaving less to finish the space nicely which kind of makes us feel like the value added is being limited even more. (As I say, there is kind of a ceiling on what we could expect to get for our house given the area, so spending the Earth doesn't make sense financially).
'Non-commital' is definitely bang on regards the planning officer - it's less helpful than I had hoped the consultation would be - I had thought going into it he would say, okay you can't do that, but here's an alternative you could do... that has not been the case unfortunately. PD or PD restrictions but bigger to get planning consent, is all I'm really getting from him - could have saved the 30 quid - I have the guidance documents already - ha!
Interesting what you said about brick slips - but that's now a conversation to be had after the one regards the foundations and the tree
Thank you all so much - nice to talk with people willing to give opinions with some knowledge to back them up

AdamBloke

just realised I've been using the wrong terminology - plinth not pad foundations... sorry - been learning so much new stuff and forgetting half of it!
for eg - the 'swift plinth' is one company providing these for garden rooms/log cabins et al.

Petriix

I don't see why you don't just build a 'conservatory' with a relatively lightweight but solid flat roof which is properly insulated. As long as you retain external doors between it and your main house and don't connect it to your main heating, there's nothing to stop you insulating sufficiently.

AdamBloke

@Petriix - a valid question... that was my hope at one point but the planning officer seemed to be saying that that was not allowed because it wouldn't qualify as a conservatory unless it was 50% glazed walls and 75% glazed roof... at least that was my understanding - please correct me if I'm wrong, because I would LOVE to be able to do that - using external doors between extension and house and heating it separately would be absolutely fine with me... perhaps I misunderstood the planning officer, but basically he seemed to say that if walls were not glass they would have to be brick to match existing, which bought us back to the original problem... ideally we would go for timber construction, 3 larch/cedar walls, 1 insulated roof and a set of sliding glass doors instead of the west wall... but my understanding was because of difference in materials from original house it is not PD and that if we went for planning they would probably refuse based on difference in materials

Edit - hmmmm. It appears there is no mention of that in the legislation or technical guidance. Just read on another site that that definition was removed in 2010. I will have to ask the planning officer about exactly that. Reading back through his emails he kind of evaded the question and gave the impression that it wouldn't be an 'appropriate' route - I took that to mean that it wasn't a conservatory, so not a discussion to be had.

gym11

We are currently in a house with an external garden room. Ours is insulated walls and roof, with glass walls on one side. When we first moved in we really  liked it but have definitely changed our opinion now!
It winter it's far too cold to use unless we run the electric heater which is then really expensive. The minute you open the door all the heat escapes into the garden so you then have to heat it up again.

In summer it's unbelievably hot. We have to have full length blinds permanently closed and then leave the door open - even then there have been afternoons in the last week or so when I've had to give up working in there. Last July/August we couldn't use it as the temperature was much constantly above 30 degrees!

When it rains it's really noisy. It's also actually a bit of pain having to walk across the garden to get to it. Especially when it's cold or wet or the ground is slightly damp. I always feel I have to put proper shoes on (not slippers!) as otherwise your feet get wet! Lighting is also something to consider - if you use it in the evenings when it's dark you need a well lit path back to the house otherwise you can easily fall over (as I've discovered!!)

We also find that we get a LOT of people staring into it when they walk past the garden. Might be less of a problem with a more private garden but it certainly feels a bit of a goldfish bowl at times.

Overall, whilst it looks impressive I'd say it's really not very practical - we dislike having to carry stuff back and forwards particularly (Laptops, Tablets etc) as the room is too hot or cold to leave electricals safely without risk or damage - just something to consider if you wanted to put teenagers and electrical equipment in one.

Doozergirl

gym11 said:

We are currently in a house with an external garden room. Ours is insulated walls and roof, with glass walls on one side. When we first moved in we really  liked it but have definitely changed our opinion now!
It winter it's far too cold to use unless we run the electric heater which is then really expensive. The minute you open the door all the heat escapes into the garden so you then have to heat it up again.

In summer it's unbelievably hot. We have to have full length blinds permanently closed and then leave the door open - even then there have been afternoons in the last week or so when I've had to give up working in there. Last July/August we couldn't use it as the temperature was much constantly above 30 degrees!

When it rains it's really noisy. It's also actually a bit of pain having to walk across the garden to get to it. Especially when it's cold or wet or the ground is slightly damp. I always feel I have to put proper shoes on (not slippers!) as otherwise your feet get wet! Lighting is also something to consider - if you use it in the evenings when it's dark you need a well lit path back to the house otherwise you can easily fall over (as I've discovered!!)

We also find that we get a LOT of people staring into it when they walk past the garden. Might be less of a problem with a more private garden but it certainly feels a bit of a goldfish bowl at times.

Overall, whilst it looks impressive I'd say it's really not very practical - we dislike having to carry stuff back and forwards particularly (Laptops, Tablets etc) as the room is too hot or cold to leave electricals safely without risk or damage - just something to consider if you wanted to put teenagers and electrical equipment in one.

How much insulation do you have?  It doesn't sound like you put enough in, especially if the roof is noisy as well.