Planning an extension

[jeds]

First thing to do is establish the location of the sewer and, preferably, the depth of two manholes. One up line and one down line. From that you can establish the approximate depth of your foundation.

I never send detailed plans at this stage. Just get hold of a basic OS pdf map and mark the sewers and manholes on with the outline of your proposed extension. Also include the relevant depths. Then add a description of your proposed foundation. What it says depends on the depths and how far away the sewer line is from your foundation. If it's within about a metre I would say that your proposal is to excavate equal to the invert depth. If it's further away you can be slightly higher based on a 45° angle from the bottom edge of your foundation. If the sewer is 2.5m deep or more you've got a problem. If you are building over you need to provide a cctv survey as well.

 

[cjard]

cross sectional foundation arrangements means you imagine that your house, extension and garden was a cake, you slice it in half an look at the filling, then draw what you see on the inside of the slice in a sketch to them, marking angles and distances between the bottom of the foundations and the bottom of the inside of the sewer pipe (the "invert level")

 

[bongos]

First thing to do is establish the location of the sewer and, preferably, the depth of two manholes. One up line and one down line. From that you can establish the approximate depth of your foundation.

Sorry about the delayed reply. I finally managed this yesterday. The conservatory (well hot tub to be precise) has been built on top of the only manhole, although the cover has been wedged in the pit at about 45° I have some sort of access. There are no other inspection pits though. Am I correct to assume then that the depth of my foundations will be the same as that of the sewer pipe - or slightly more so that a concrete lintel can be laid over the pipe?

I never send detailed plans at this stage. Just get hold of a basic OS pdf map and mark the sewers and manholes on with the outline of your proposed extension.

We still have the water/drainage searches from when we bought the property in January - I assume I could use these?

Then add a description of your proposed foundation. What it says depends on the depths and how far away the sewer line is from your foundation. If it's within about a metre I would say that your proposal is to excavate equal to the invert depth. If it's further away you can be slightly higher based on a 45° angle from the bottom edge of your foundation. If the sewer is 2.5m deep or more you've got a problem. If you are building over you need to provide a cctv survey as well.

I've added a pic of where the sewer runs. At a guess (I can't get a proper look in it with the hot tub and cover wedged) I would think it is around ~30-40cm deep as this is what next doors is when I had a cheeky look. There's is the beginning of the run so mine would be a liyyle deeper. It is around 1m away from the house as thought though i'm now realising that the soil stack coming down the outside wall in the centre (roughly in line with the manhole) could well make things interesting and that i'm probably going to have to ask for an additional connection.

cross sectional foundation arrangements means you imagine that your house, extension and garden was a cake, you slice it in half an look at the filling, then draw what you see on the inside of the slice in a sketch to them, marking angles and distances between the bottom of the foundations and the bottom of the inside of the sewer pipe (the "invert level")

Thank you. Makes sense now.

 

[ban-all-sheds]

Am I correct to assume then that the depth of my foundations will be the same as that of the sewer pipe

I believe they need to be deeper.

 

[bongos]

So, as I type the very basic drawings are with Thames Water for a build over application.

I now have another couple of questions regarding the certificate of lawfulness if anyone's able to help.

1. Do I need a certificate of lawfulness. Ok, I know I don't need one - my extension is single storey and no more than 3m extra on the rear etc and Waltham Forest don't require it. But is it advised? I don't begrudge paying the £86 so much, it's the 8 weeks I've been told that it will take that's frustrating.
2. Assuming it's advised I do get one, where best to get the 1:1250 map that the council apparently need to complete it. I would have thought they have their own maps. But then I thought that about Thames Water too...

Any advice appreciated!

 

[ban-all-sheds]

1. Do I need a certificate of lawfulness. Ok, I know I don't need one - my extension is single storey and no more than 3m extra on the rear etc and Waltham Forest don't require it. But is it advised? I don't begrudge paying the £86 so much, it's the 8 weeks I've been told that it will take that's frustrating.

A week ago I wrote to the DCLG:

-------------------------------------------------------------
On your site

https://www.gov.uk/government/uploa.../191487/Letter-Extensions-April2013-Final.pdf

the Secretary of State says "There is no need for residents to purchase a Lawful Development Certificate from the council to provide certainty that they have the rights to extend their home."

But in the guidance document from my council it says

The only way to determine the lawfulness of a proposed single storey rear
extension is for householders to apply to the Council for a Certificate of Lawful
Proposed Development. The Council strongly encourages this route. For those
proposing an extension under the new legislation, i.e. more than 4 metres
beyond the rear wall of the original dwellinghouse (in the case of a detached
house) or 3 metres in any other case, a Certificate of Lawful Proposed
Development should be made following confirmation that no prior approval is
required.

This seems to directly contradict the information on the DCLG site, and I would appreciate knowing which of you is correct.

I must say that it seems odd that for an extension clearly within the size limits defined in S.I 2013 No. 1101, which has gone through the prescribed Neighbour Consultation process, has had no objections, and been declared by the council to be Permitted Development, I should then have to pay the council for them to confirm it can be built.

-------------------------------------------------------------


They tell me I can expect a reply within (hopefully) another 6 working days.

2. Assuming it's advised I do get one, where best to get the 1:1250 map that the council apparently need to complete it.

//www.diynot.com/forums/building-regs-planning/downloadable-site-plans.398071/

 

[bongos]

They tell me I can expect a reply within (hopefully) another 6 working days.

Many thanks Ban. This makes me actually want to wait the 6 working days to see what your reply is! My guess is some washed out sort of answer that doesn't really provide an answer, just more questions... Such a cynic I know!

//www.diynot.com/forums/building-regs-planning/downloadable-site-plans.398071/

Via the Planning Portal accredited suppliers it is then. Or it will be if I've decided I'm going for a certificate of lawfulness. I'm shying away from it now - might just ring the borough see what they say..

Edit: Well, I rang the borough and they said they advise it...

 

[ban-all-sheds]

I will report back as soon as I hear anything.

Hopefully I'll get my consultation package ready for submission over the Easter break - once it's been through the mill (assuming it gets the OK), I will then ask my council in writing to explain why I should pay them for an LDC when the Secretary of State says I do not need to.

 

[cjard]

the guidance document from my council it says

The only way to determine the lawfulness of a proposed single storey rear
extension is for householders to apply to the Council for a Certificate of Lawful
Proposed Development. The Council strongly encourages this route. For those
proposing an extension under the new legislation, i.e. more than 4 metres
beyond the rear wall of the original dwellinghouse (in the case of a detached
house) or 3 metres in any other case, a Certificate of Lawful Proposed
Development should be made following confirmation that no prior approval is
required.

When I read this, it seems like the context is one of a situation where the lawfulness of an extension is being called into question. I'd hasten to add that this would not be the default position for all extensions (that they're unlawful unless found otherwise by the council and confirmed in writing by way of issuance of a CLPD)

They also say "should" rather than must; more imperative than a could, but still with flexibility to not be the outright lie that use of the would "must" would give rise to. It's misleading depending on the reader's perspective and may well be responsible to compelling people to needlessly contribute to the council coffers, but that's normal

2. Assuming it's advised I do get one, where best to get the 1:1250 map that the council apparently need to complete it.

//www.diynot.com/forums/building-regs-planning/downloadable-site-plans.398071/[/quote]

Land registry title plans are 1:1250, not that you're allowed to reproduce them without permission, but they're only £3 (?) and I don't think buying it and then handing it to the council as a "here's the title plan according to the land registry" is "reproduction"..

 

[cjard]

We know pretty much want we want to build. I am terrible at drawing (far beyond just bad) though am happy enough to have a bash.

Watch a few tutorials about Google SketchUp on youtube; you'll soon see that when using that program, stuff nearly draws itself. Sketching out 2D plans is so ridiculously easy, it'd take me about 10 minutes to show you

 

[ban-all-sheds]

When I read this, it seems like the context is one of a situation where the lawfulness of an extension is being called into question.

Indeed, but how can it be?

The law says that a rear extension under a certain size is PD if the neighbour consultation process is followed and none of the people consulted object.

So a rear extension under that certain size goes through the neighbour consultation process, none of the people consulted object, and the council decree that it is PD.

On what basis could someone subsequently challenge the lawfulness of the extension?

 

[cjard]

I don't think they could, but it wouldn't stop the ignorant (which may extend to their solicitor) trying. It might be that the council have had a high number of complaints and now recommend everyone gets a LDC because
a) it heads off any potential argument without the council having to throw time and resource at it (e.g. having some planning officer write a letter of confirmation that it's OK to all parties concerned) and
b) the LDC brings money in

Prevention is better than cure, especially if prevention is a revenue stream and cure is a cost ?

 

[bongos]

So TW have given me buildover permission. Initially they said they required more information on the type of foundations along with a cross sectional drawing. I rang them and explained i wasn't too sure exactly what they needed so they emailed me an example. I removed their name from it and emailed it back saying this was what i was doing and they were happy to pass it off. I also included a comically bad paintbrush drawing of the plan of the extension with additional "Y" connection to allow rodding access and they were fine with that.

My next question is regarding the Party Walls Act... I plan to build up to but not over the boundary line, or leaving a small gap. Does this require party walls consent? I thought not but im not too sure - im trying to keep everything as simple as possible as the property on one side is owned by an Egyptian (who lives back in Egypt) and the tenants know very little about him , just paying the cash rent to a mysterious gentleman who turns up late at night! Classic London really...

Oh and Bas - I decided not to bother with the certificate of lawfulness in the end. The extension is within permitted development and another architect friend said they wouldn't either so i was sold!

 

[uscmba]

Hi bongos, very glad you got buildover permission. I have similar problem: need to have house extension but there is public sewer in the garden. Can you send me or upload the examples (plan/drawing) that Thames Water gave you regarding "relocate the manhole using "Y" connection to allow rodding access"? hanks very much!

So TW have given me buildover permission. Initially they said they required more information on the type of foundations along with a cross sectional drawing. I rang them and explained i wasn't too sure exactly what they needed so they emailed me an example. I removed their name from it and emailed it back saying this was what i was doing and they were happy to pass it off. I also included a comically bad paintbrush drawing of the plan of the extension with additional "Y" connection to allow rodding access and they were fine with that.

My next question is regarding the Party Walls Act... I plan to build up to but not over the boundary line, or leaving a small gap. Does this require party walls consent? I thought not but im not too sure - im trying to keep everything as simple as possible as the property on one side is owned by an Egyptian (who lives back in Egypt) and the tenants know very little about him , just paying the cash rent to a mysterious gentleman who turns up late at night! Classic London really...

Oh and Bas - I decided not to bother with the certificate of lawfulness in the end. The extension is within permitted development and another architect friend said they wouldn't either so i was sold!