rear extension.

[essex123456]

We currently have a conservatory that is on its last legs. I would like to replace with an extension. Either with roof lantern or velux, bi fold doors etc on the back. I know you can get a lot of this off the shelf from the likes of SELCO. It is a semi detached property. I have not done this before but I am competent, having done the rest of the house up, built a large workshop etc.. I also have a mate who is competent builder to help advise me.

My question is what do I need plan wise? I have spoken to a couple of architects, but they are going on about structural engineers etc. I think this is all over kill. the rear wall of the house has a patio door that leads into the conservatory from one room, and a door and window leads into it from another. My plan would be to open these openings up as they obviously have lintels in place. If I wanted to make these openings a bit wider I could get off the shelf steel lintels. The conservatory base will need ripping up as you step up into it. Therefore a new foundation to support the new walls would be put in place. I have seen other projects on here where people have revamped conservatories or done rear extensions. I'm looking to open up the existing door ways a bit and put a simple extension on the rear, not to rip walls out so its all open plan. Can some one point me in the right direction? I don't want to spend money on architect if its not needed. I know I have to meet building Control.

I can put pics up if that helps.

 

[tony1851]

If you keep the extension size within the permitted development rules (eg max 3m out from the rear wall) you won't need planning permission, so no plans for that.
With regard to Building Control, you can do that without plans as well, under the Building Notice procedure, but you have to be sure you know the regs as the building inspector will still inspect.

 

[essex123456]

If you keep the extension size within the permitted development rules (eg max 3m out from the rear wall) you won't need planning permission, so no plans for that.
With regard to Building Control, you can do that without plans as well, under the Building Notice procedure, but you have to be sure you know the regs as the building inspector will still inspect.

Hi yes was going to keep it at the 3m limit. Can I get a copy of building regs from Council? Thanks

 

[Notch7]

Hi yes was going to keep it at the 3m limit. Can I get a copy of building regs from Council? Thanks

Its possible to download each part of the regs, it would a long time to read!

Since it will be open to the house and will be an extendion with excess glazing you will need a SAPS test to prove compliance with part L.

If its an orangery type structure with a lantern and bifolds, you will need structural calcs for flat roof loading and lateral stability as well as any steel neede for the house opening.

The flat roof can be done with glulam beams, steels or possibly just C24 softwood if its not big.

Your builder mate will prob know the current specs, it basically needs 100mm cavity walls, insulation below screed, insulation in warm flat roof.

 

[Leofric]

Can I get a copy of building regs from Council?

You can view bldg. regulations Approved Documents on The Planning Portal or LABC websites ,but if you don't know how to obtain bldg regs how can you expect to know how to comply with the relevant parts relating to your extension
Wouldn't it be better to employ an architect or architectural technician to draw the plans and obtain the necessary approvals for you. They would also deal with a structural engineer to obtain the necessary structural calculations for approval as part of a Full Plans Submission for Building Regulations approval. You could ,of course, just build it under a Building Notice and hope everything complies when the Building Control Officer inspects the work on site.
( or risk abortive work if any work that doesn't comply has to be redone)

 

[^woody^]

Building notice it is.

The OP does not want to spend money on an architect, does not see the point of a structural engineer, and does not even know where to get the "building regulations" let alone what they are.

The pioneering spirit is strong, but if I was the building inspector on this one, I'd be phoning in sick for a while.

 

[essex123456]

Thanks for the replies.

I was taking inspiration from this thread https://www.diynot.com/diy/threads/48sqm-kitchen-extension-£30k-all-in.507260/

 

[tony1851]

@op.
You don't want the cost of an architect or SE, or even an architectural technician, but absent those if you or your mate make mistakes, they can be expensive to rectify.
Try this short quiz on points relevant to a simple lean-to extension; if you fail one of them (or don't know how to find out) you should reconsider not getting someone to detail the work for you. Remember that some inspectors can be helpful and offer advice - most won't have the time.

Q1. What is the minimum length of return you need adjacent to the bifolds?
Q2. What is the minimum air gap you need between the top of the roof insulation and the underside of the felt?
Q3. If you are merging/widening any of the openings in the existing wall, would you know what lintel you would need to justify it
to the inspector (that doesn't include saying that the man in the builders' merchants yard said "this'll do").
Q4. Do you know how to work out the maximum area of glazing you are normally allowed in an extension?

 

[Notch7]

The reg Ive forgotten before is the need for a mains smoke alarm, when adding an orangery open to the house.

I cant remember the reg / reason.......

 

[^woody^]

The reg Ive forgotten before is the need for a mains smoke alarm, when adding an orangery open to the house.

I cant remember the reg / reason.......

Do oranges even burn?
When you remember, let us know, because that's a new one for me.

 

[Notch7]

Do oranges even burn?
When you remember, let us know, because that's a new one for me.

Well I did a job last year, an orangery making an open plan kitchen diner and the bc wanted one. I assumed it was due to tge kitchen, but I also did a conservatory job that was open to the lounge, that needed one too -I think it was on the architects building regs dwg.

 

[Leofric]

Thanks for the replies.

I was taking inspiration from this thread https://www.diynot.com/diy/threads/48sqm-kitchen-extension-£30k-all-in.507260/

It is ok to take inspiration from other projects but you need architectural drawings to at least Building regs standard for your specific job.
Tony1851 mentions some points but there are various other technical considerations of course.
Anyway , it is up to you , let us know when you have decided which way to go . ( woody's comments should be good for a laugh at least )

 

[cve80671]

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[mrrusty]

You will need a structural engineer for Building regs submission and to be honest for simple rear extension the cost may be ranging anywhere from £500-£1000

architect for around £1500-£2000

That's £2.5-£3K for a small extension before you start. As Tony said post #2, it isn't always necessary if you get a decent builder. Just completed a small extension - very simple on the back of a small semi that required a new 2.7m opening. I did the simple plans for the builder myself - nothing fancy just a lean-to side/rear extension extending an existing small lean-to kitchen with patio doors, a couple of windows and veluxes. Done on building notice with a builder I trust, and known to the local BC. My son (C.Eng MICE) checked the beam calcs I ran myself using an on-line calculator and that printed the result https://www.steelbeamcalculator.co....EcPxBWwZgYNlj6GJztxt7YFVFt3LLHqxoC_XQQAvD_BwE. Cost £30 to register to use. My builder "guessed" exactly the same size beam as the calculator suggested (actually the calculator suggested the outer of two parallel beams on a cavity wall could have been a bit smaller, but we kept them the same) - he said he'd done loads of similar and knew what was needed. BC inspected the beam installation during build. Everything signed off at the end. The beam calcs were never even asked for by BC, and as it was a notice, no plans were ever submitted to BC.

The main thing is a builder you can trust to build to regs. if you don't have this then BC full plans is the way to go, BUT it isn't the only route - you can save money, but do be aware of the risks.

 

[cve80671]

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