Replacing conservatory and ? Knocking through

10 Mar 2015
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United Kingdom
Wondering if anyone can help here. We have just bought a victorian end terrace house (on the corner of the street) which has had an extension onto the side of the original kitchen (a bit like a side return extension, but a bit wider than the house- actually to the boundary wall). Along the side of the house, leading to the extension is a long thin conservatory, 6x1.5m. There are also old French doors to this space from the second reception. As this space isn't very usable I wondered about knocking through the second reception side wall (adding an rsj) to make this room a bit bigger. Quotes for a proper extension were prohibitive (22-26k) so we are thinking about just replacing the conservatory and knocking through. I understand that this would in theory make the conservatory an extension, but as long as it meets requirements for height etc can be done under permitted development. Does the fact that it won't be insulated as well as an extension affect permitted development? Does the amount of glazing affect any of this? Is it possible to build up the dwarf wall and just have a glazed roof (we'd have to have obscured glass on the side windows anyway)?
Any thoughts or suggestions welcome!
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It might well be permitted development, but would fall foul of Building Regs.
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How many quotes did you get, on the face of it £25K sounds awfully expensive for a 9m2 extension and breakthrough.

And the lack of anything to quote from will often add a hefty premium.
Only one, but he explained that it was because of the length of wall/ foundations that would have to be dug, that because of its shape it's a lot of work for not much area. Doing the same but with replacing the conservatory we were quoted 15k (no digging of foundations) from someone else.
Sounds peculiar, just how long would a foundation be on a 6m extension? As mentioned no drawings, big premium.
What do you mean? It was an architect who was suggesting the 25k figure. He also seemed on the cheaper side for build cost of a loft conversion when compared to the quotes I have had for the complete package. So not sure if this might also be on the cheaper side. Maybe it's worth getting a quote from a builder?
Re the loft conversion I've had a quote for hip to gable loft conversion of £40-£43k from companies doing the lot, he suggested a build cost of £30k, so his fees, fittings, building regs etc on top, but still significantly cheaper than the other quotes. Makes me wonder whether the £30k might be optimistic. Hence, maybe the extension is optimistic too.
No, because it seemed pointless of it was going to be that expensive! Also, does it make a difference that the wall used as the dwarf wall is the street wall? Ie the other side is pavement? Would be hard to make foundations there I'd have thought?
A friend of mine has had quotes for a 10ft by 12ft extension of 28-40k, having had the plans drawn. I don't think £25k would be unrealistic in this case.
OK, well seeing as its facing a road then you’ll need planning permission. Even if you demolish the old one and replace it, it will require PP. Extensions facing a highway are not Permitted Development.

A foundation built on the boundary with the wall not in the centre needn’t be overly expensive, just needs to be designed by an SE, it’s called an eccentric foundation and not uncommon when building along a boundary.

It’s a bit of a chicken and egg really, if you want accurate quotes then you’ll need something accurate from which good builders can quote from. There’s a couple of (good) builders down here who work by recommendation only and they will simply not quote unless they have a set of Building Regs drawings. Otherwise they’re just guessing and they will more often than not guess high. They will also be very wary that you are not committed (and they’d be right) so they will not expel much if any effort in doing you a proper quote. Why should they? I do quotes regularly for people (for drawing work) and can tell you those people who phone me up and just ask for a ball park figure over the phone without letting me see their house etc so that I can actually quote properly, never, ever come back. Nowadays if people phone up for a ballpark I know the jobs dead before I finish the conversation, I roll my eyes and pluck a figure out of the air.

BTW an architect is overkill, an architectural technician is all that is required.
We had the architect quote as he came highly recommended and we were wanting some inspiration, something builders tend not to have.

The street it is facing is a side elevation not primary, and I believe that this may be considered ok as permitted development. As I said there is currently a disgusting conservatory there so hopefully the fact we are looking at improving this will help our cause if it did need planning.

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