House extension...footings required.

[Unbelievable Jeff]

Ok, so we have some pretty knowledgable people on this forum, so I was wondering if you could help me out...

 

I bought a house 2 years ago that needed extreme internal remodelling. I have been doing this with my father in law over the last 2 years, 1 day a weekend, and has included partial removal of load bearing walls, removal of stud walls, creation of new doors, moving of stairs etc. We have done this without Building regs due to the fact that it costs a decent amount when you're doing so many small jobs that need it, and the impracticality of having people round to check it. When we bought the house we had to get some indemnity insurance due to the fact that an extension had been built and altered without building regs approval (I believe it was a garage that was converted into a lounge). We do have calculations for all the steels we have put in etc, and it's finished to a really high quality within building regs but we're hoping this won't really matter in the long term - the only issue will be if the council "find out" that we've been doing it and we have to prove all the work. Anyway, I degress.

 

We are looking to put a single storey extension on the back of our kitchen to make it a kitchen/diner. It is around 4m wide by 5m long, and will consist of two walls (left and end walls) of bi-folding doors, and a third wall (right) that will be solid as it is at the edge of the boundary. What I wanted to know is about foundations. When we were looking at putting a timber frame double garage down at the bottom of our garden we were told we need to construct a concrete base to place this on. If we were to put in a timber frame for our extension, will we need to put 'proper' foundations down or could we put down a solid concrete base - we will be digging at the boundary next to the foundations of next doors extension and I'd prefer not to have to give them the opportunity to appoint a surveyor as this can be very costly and waste time. A timber frame extension would be a lot lighter, so I was wondering what our options are here. Anyway, any advice would be appreciated.

[Tony F]

I have built my own house and have some experience. But no way an expert.

 

Firstly it depends on what sort of soil/rock your house is built on as to what foundations you need. Secondly, given that you're wanting to do this under the Bdg Regs radar, you should (in my opinion) be very certain you're not cutting corners as you may find that the house is unsellable in future or - even if you're not wanting to sell, you'll look pretty foolish if the extension starts coming away from the house becasue you scrimped on the foundations.

 

You say that the RH wall is next to the boundary but not what is on the other side or how far away. Assuming reasonably hyard (but diggable) ground, if you hand dig the foundations you can dig right up to the boundary - but if you're closer than 1m then your neighbours can object and then you're in a whole world of hurt. You also don't say whether you get on well with your neighbours or not (as this can often be a deciding factor). Obviously, regardless of your relataionship, if the boundary is actyually the outside wall of someone else's living room then you'll need to find another way.

[Special K]

If you are digging any sort of foundation within 3 metres (i think) of the neighbours foundations, you are advised to get a party wall agreement in place. However, it is not necessary and if you have a decent rapport with you neighbour, then it is always worth approaching them for a non formal agreement. Even if you do need one, you don't need a Surveyor to draw one up and there are templates available online for you to use. also, it sounds as though your planned extension is within Permitted Development rights, but it is worth getting the council to confirm. For £30 (ish) they will give you the all clear or advise otherwise.

 

Regarding the timber frame and the foundations, much will depend upon the ground conditions of your garden and the levels you are working with and to. Generally though, you will need concrete pads to support the timber frame and a strip footing to support the masonry infill panels or the below ground masonry and timber walls that sit on top of them (depending upon your design). As is usual with small extensions, you will need the building inspector to come out and witness the ground conditions so that the excavation depth has exposed good bearing conditions for the foundation. Alternatively you could get a ground bearing raft foundation which is also your ground floor slab, but this will invariably be thicker than a normal slab. Your Structural Engineer will advise as to the best way forward. I would be very reluctant to build any extension without foundations supporting all the external walls. You would also be well advised to get BC sign off for the works, especially if you ever come to sell the place. and if you are amending gas and /or electric installations, boiler positions, etc, then the relevant tickets will be required for Gas Safe and Part P (depending upon design) compliance.

 

Another thing, if you have a suspended ground floor to your existing house and you are extending with a ground bearing slab, don't forget to extend the ventilation to the existing floor under the new slab (some drainage pipes, connectors and a few air bricks will suffice).

[Unbelievable Jeff]

If you are digging any sort of foundation within 3 metres (i think) of the neighbours foundations, you are advised to get a party wall agreement in place. However, it is not necessary and if you have a decent rapport with you neighbour, then it is always worth approaching them for a non formal agreement. Even if you do need one, you don't need a Surveyor to draw one up and there are templates available online for you to use. also, it sounds as though your planned extension is within Permitted Development rights, but it is worth getting the council to confirm. For £30 (ish) they will give you the all clear or advise otherwise.

 

Regarding the timber frame and the foundations, much will depend upon the ground conditions of your garden and the levels you are working with and to. Generally though, you will need concrete pads to support the timber frame and a strip footing to support the masonry infill panels or the below ground masonry and timber walls that sit on top of them (depending upon your design). As is usual with small extensions, you will need the building inspector to come out and witness the ground conditions so that the excavation depth has exposed good bearing conditions for the foundation. Alternatively you could get a ground bearing raft foundation which is also your ground floor slab, but this will invariably be thicker than a normal slab. Your Structural Engineer will advise as to the best way forward. I would be very reluctant to build any extension without foundations supporting all the external walls. You would also be well advised to get BC sign off for the works, especially if you ever come to sell the place. and if you are amending gas and /or electric installations, boiler positions, etc, then the relevant tickets will be required for Gas Safe and Part P (depending upon design) compliance.

 

Another thing, if you have a suspended ground floor to your existing house and you are extending with a ground bearing slab, don't forget to extend the ventilation to the existing floor under the new slab (some drainage pipes, connectors and a few air bricks will suffice).

 

Excellent, thank you very much.

 

We will get BC involved for the extension for sure - we will make sure the extension is legitimate. We do have planning permission for it, even though I'm not sure we actually need it.

 

We are on good terms with the neighbours, I just worry it could become costly if they decide to appoint a surveyor. I'll have a word.

 

Am I right in thinking that we only need an agreement if the foundations are at a lower level than their's?

 

Is there an option where we don't use masonry walls, or is a masonry shell always needed?

[Unbelievable Jeff]

I have built my own house and have some experience. But no way an expert.

 

Firstly it depends on what sort of soil/rock your house is built on as to what foundations you need. Secondly, given that you're wanting to do this under the Bdg Regs radar, you should (in my opinion) be very certain you're not cutting corners as you may find that the house is unsellable in future or - even if you're not wanting to sell, you'll look pretty foolish if the extension starts coming away from the house becasue you scrimped on the foundations.

 

You say that the RH wall is next to the boundary but not what is on the other side or how far away. Assuming reasonably hyard (but diggable) ground, if you hand dig the foundations you can dig right up to the boundary - but if you're closer than 1m then your neighbours can object and then you're in a whole world of hurt. You also don't say whether you get on well with your neighbours or not (as this can often be a deciding factor). Obviously, regardless of your relataionship, if the boundary is actyually the outside wall of someone else's living room then you'll need to find another way.

 

We'll definitely get building regs for the extension, it's just the internal work we're not currently.

 

On the other side of the wall is their extension which protects about 1m out from the house, so the remaining 4m there isn't anything, but for that first meter there is.

 

I don't know the soil composition, I'll get someone out to look at this. It's currently covered by a patio...

[Special K]

Excellent, thank you very much.

 

We will get BC involved for the extension for sure - we will make sure the extension is legitimate. We do have planning permission for it, even though I'm not sure we actually need it.

 

We are on good terms with the neighbours, I just worry it could become costly if they decide to appoint a surveyor. I'll have a word.

 

Am I right in thinking that we only need an agreement if the foundations are at a lower level than their's?

 

Is there an option where we don't use masonry walls, or is a masonry shell always needed?

 

The Agreement is (theoretically) needed if you dig near or below the foundation level of their property, so yes, you will probably fall into that category with any type of dig, i'm afraid - https://www.gov.uk/party-walls-building-works/work-tell-your-neighbour-about - will give you more info.

 

There is generally a need for masonry below ground which acts, among other things, as a support for the walls above. If you use a raft foundation, you can build off that with any type of infill panels, providing the proper weathering details are incorporated. But for bi fold channel supports, draining of cavity, etc, a bit of masonry up to damp is recommended. It generally works out well for a bit of flexibility and is quicker too, although everyone will have an opinion!

[Unbelievable Jeff]

The Agreement is (theoretically) needed if you dig near or below the foundation level of their property, so yes, you will probably fall into that category with any type of dig, i'm afraid - https://www.gov.uk/party-walls-building-works/work-tell-your-neighbour-about - will give you more info.

 

There is generally a need for masonry below ground which acts, among other things, as a support for the walls above. If you use a raft foundation, you can build off that with any type of infill panels, providing the proper weathering details are incorporated. But for bi fold channel supports, draining of cavity, etc, a bit of masonry up to damp is recommended. It generally works out well for a bit of flexibility and is quicker too, although everyone will have an opinion!

 

Excellent, thanks also for this.

[sadoldgit]

Had a guy in this morning to give me advice about a brick extension to my house. He says that I will need to go down a metre for the foundations and that is standard for single or double story extensions.

[Goatboy]

Had a guy in this morning to give me advice about a brick extension to my house. He says that I will need to go down a metre for the foundations and that is standard for single or double story extensions.

 

Get a new builder.

[Jonnyboy]

While we're on topic can anyone recommend someone who does decent + cheap loft conversions?

[Dimond Geezer]

Foundations are generally 1m deep & 600mm wide, but this is dependent upon ground conditions, such as quality of the bearing soil, site slope, proximity of trees, type of soil, for example if you have clay soil you may need to take precautions to avoid heave, this is all something the Building Inspector will advise. I would strongly advise against avoiding Building Regs, the cost of retrospective works, or even demolition, will be far in excess of saving £500 on fees.

The Party Wall agreement mentioned elsewhere is mandatory, not optional, although in it's simplest form, is simply an exchange of letters with a sketch or two.

[Unbelievable Jeff]

Foundations are generally 1m deep & 600mm wide, but this is dependent upon ground conditions, such as quality of the bearing soil, site slope, proximity of trees, type of soil, for example if you have clay soil you may need to take precautions to avoid heave, this is all something the Building Inspector will advise. I would strongly advise against avoiding Building Regs, the cost of retrospective works, or even demolition, will be far in excess of saving £500 on fees.

The Party Wall agreement mentioned elsewhere is mandatory, not optional, although in it's simplest form, is simply an exchange of letters with a sketch or two.

 

As said above I will definitely be getting building regs for this extension.

[Dimond Geezer]

As said above I will definitely be getting building regs for this extension.

 

Ok, sort of sporadically read through it whilst fielding phone calls & getting hassle from my boss, guess what about......yep foundation design.

[Unbelievable Jeff]

Ok, sort of sporadically read through it whilst fielding phone calls & getting hassle from my boss, guess what about......yep foundation design.

 

Ha, no worries, didn't mean to come across as shiťty if it did!

[egg]

While we're on topic can anyone recommend someone who does decent + cheap loft conversions?

 

You won't get a decent job done cheap. You'll get one or the other.

 

I did a loft conversion on a rental house a few years ago. I broke the jobs down and used a chippy to install the stairs, then cut through, then beef up the joists, then lay the floor and put up the stud work frames. The sparky then came in and did the first fix. Roofer installed a velux. I stapled up the insulation. Chippy finished stud work and hung doors. Next were the plasterers followed by the sparky to second fix. Job done.

 

It was surprisingly simple and breaking it down saved us over ten grand. We paid about £8k iirc for the whole job.

 

My advice is to get the drawings done and then get prices from the various trades for their bit and manage the build yourself.

[Jonnyboy]

You won't get a decent job done cheap. You'll get one or the other.

 

I did a loft conversion on a rental house a few years ago. I broke the jobs down and used a chippy to install the stairs, then cut through, then beef up the joists, then lay the floor and put up the stud work frames. The sparky then came in and did the first fix. Roofer installed a velux. I stapled up the insulation. Chippy finished stud work and hung doors. Next were the plasterers followed by the sparky to second fix. Job done.

 

It was surprisingly simple and breaking it down saved us over ten grand. We paid about £8k iirc for the whole job.

 

My advice is to get the drawings done and then get prices from the various trades for their bit and manage the build yourself.

 

Thanks. £8k sounds a lot better than 18k. So start with a good chippy first.

[egg]

Thanks. £8k sounds a lot better than 18k. So start with a good chippy first.

 

Yep. If you need to remove trusses and or add steels or straps etc then things get messier but if you get a specific tradesman to do a specific job you should be fine.

[Coxford_lou]

You're all so manly!

[Jonnyboy]

You're all so manly!

 

I don't mind you coming to have a crack at it for me Lou. Free tea and coffee.

[Whitey Grandad]

I don't mind you coming to have a crack at it for me Lou. Free tea and coffee.

 

Be wary of builders and their cracks...

 

https://c1.staticflickr.com/9/8333/8366591037_f91442e831_z.jpg

[Jonnyboy]

Yeah OK some sort of g-string would have to be worn.

[the colonel]

Get a new builder.

 

Why should he, he is correct but is dependant on ground conditions....i.e. if you are on clay and Laylandii are within a certain distance you could end up putting piles it. Yes this is an extreme but had do do it on mate of mine's place in Uxbridge that is on London clay. Generally building control will not accept less than 1m deep unless solid substrata allows shallower.

 

U.Jeff:

 

It sounds like you are spending quite a lot of money so why take short cuts. The problem is when you come to sale the house the surveyors and conveyancers will pick up on the lack of required approvals, as you found when you purchased the house. This will likely have an adverse effect on future value.

 

- You need to consider planning, but recent relaxation in planning laws probably means you are ok

- Building Reg's. The type of work you want to do and have done can be done on what is called a 'building notice'. This is an application to the Council (or approved inspector, these are private building control companies and not council) means you can have very basic drawings and the Council Building Control Officer will provide guidance as you build and will provide advice and answer the queries you have.

- Party Wall etc Act 1996 - if you are building within 3m of a neighbour's property and your foundation is deeper than the neighbour's foundation and/or you are building up to the boundary line you have to give notice to your neighbour (this is not an exhaustive list but sounds applicable for what you are doing). If you don't they can take an injunction out and stop you progressing until a notice is serve and formal Party Wall Award is drawn up. Best way is you speak to them about what you want to do, provide them with a sketch and get agreement from them that they do not object to your works.

- Another thing to be wary of is Construction Design & Management Regulations (CDM), these are health & safety procedures specifically for the construction industry. At the moment these regulations are only applicable to commercial works but from April 2015 they will apply to domestic residential. the exact rules are yet to be finalised.

 

Also if your mortgage company were to find out what you are doing your mortgage could be at risk.

 

Not following procedures because they are expensive and a waste of time is fine when everything is going ok. But if things start to go wrong not following procedures can be a lot more expensive. If Building Control were to find out they have the power to force you to open up finished work and even to take things down if incorrectly constructed e.g. insufficient foundations.

 

I cannot recommend more strongly that you should seek the correct professional help.

 

Good luck.

[the colonel]

You won't get a decent job done cheap. You'll get one or the other.

 

I did a loft conversion on a rental house a few years ago. I broke the jobs down and used a chippy to install the stairs, then cut through, then beef up the joists, then lay the floor and put up the stud work frames. The sparky then came in and did the first fix. Roofer installed a velux. I stapled up the insulation. Chippy finished stud work and hung doors. Next were the plasterers followed by the sparky to second fix. Job done.

 

It was surprisingly simple and breaking it down saved us over ten grand. We paid about £8k iirc for the whole job.

 

My advice is to get the drawings done and then get prices from the various trades for their bit and manage the build yourself.

 

 

 

How did you get on with interstitial condensation?

[Unbelievable Jeff]

Why should he, he is correct but is dependant on ground conditions....i.e. if you are on clay and Laylandii are within a certain distance you could end up putting piles it. Yes this is an extreme but had do do it on mate of mine's place in Uxbridge that is on London clay. Generally building control will not accept less than 1m deep unless solid substrata allows shallower.

 

U.Jeff:

 

It sounds like you are spending quite a lot of money so why take short cuts. The problem is when you come to sale the house the surveyors and conveyancers will pick up on the lack of required approvals, as you found when you purchased the house. This will likely have an adverse effect on future value.

 

- You need to consider planning, but recent relaxation in planning laws probably means you are ok

- Building Reg's. The type of work you want to do and have done can be done on what is called a 'building notice'. This is an application to the Council (or approved inspector, these are private building control companies and not council) means you can have very basic drawings and the Council Building Control Officer will provide guidance as you build and will provide advice and answer the queries you have.

- Party Wall etc Act 1996 - if you are building within 3m of a neighbour's property and your foundation is deeper than the neighbour's foundation and/or you are building up to the boundary line you have to give notice to your neighbour (this is not an exhaustive list but sounds applicable for what you are doing). If you don't they can take an injunction out and stop you progressing until a notice is serve and formal Party Wall Award is drawn up. Best way is you speak to them about what you want to do, provide them with a sketch and get agreement from them that they do not object to your works.

- Another thing to be wary of is Construction Design & Management Regulations (CDM), these are health & safety procedures specifically for the construction industry. At the moment these regulations are only applicable to commercial works but from April 2015 they will apply to domestic residential. the exact rules are yet to be finalised.

 

Also if your mortgage company were to find out what you are doing your mortgage could be at risk.

 

Not following procedures because they are expensive and a waste of time is fine when everything is going ok. But if things start to go wrong not following procedures can be a lot more expensive. If Building Control were to find out they have the power to force you to open up finished work and even to take things down if incorrectly constructed e.g. insufficient foundations.

 

I cannot recommend more strongly that you should seek the correct professional help.

 

Good luck.

 

Thanks Colonel.

 

My father in law is a retired builder and has done this to 4 houses over the last 6 years, including our last plac, and it didn't cause any issues with selling any of them. As said, we already have half our house missing building regs, so I can't really see what difference it makes If we do the same on the other side. The indemnity insurance covers us for any costs incurred whilst proving to the council that the work has been done properly. Unfortunately we don't have any drawings because I designed the new interior, and the drawings are not professionally done. We have sign off for all the gas, electric, stairs etc from the separate trades.

 

The internal work will be completed by the end of this year and then we can start on the extension. I'm not others about cutting corners on the extension, it is what it is and will be done to regulation, I just wondered whether you needed full depth foundations if you use timber frame construction.

 

We do have full planning permission for the extension.

 

I don't know how the mortgage company would find out personally...But even then we'd just move the mortgage if it was an issue.

 

Just as an aside, how would the surveyors/conveyancers etc know that we've made any changes to the interior?

 

Thanks for your input on this.

Edited 18 February, 2015 by Unbelievable Jeff

[Dimond Geezer]

Ha, no worries, didn't mean to come across as shiťty if it did!

 

No probs.

 

As an addition to The Colonels list, make sure your insurance company is aware that you are having structural work done to your property.

[Special K]

Thanks Colonel.

 

My father in law is a retired builder and has done this to 4 houses over the last 6 years, including our last plac, and it didn't cause any issues with selling any of them. As said, we already have half our house missing building regs, so I can't really see what difference it makes If we do the same on the other side. The indemnity insurance covers us for any costs incurred whilst proving to the council that the work has been done properly. Unfortunately we don't have any drawings because I designed the new interior, and the drawings are not professionally done. We have sign off for all the gas, electric, stairs etc from the separate trades.

 

The internal work will be completed by the end of this year and then we can start on the extension. I'm not others about cutting corners on the extension, it is what it is and will be done to regulation, I just wondered whether you needed full depth foundations if you use timber frame construction.

 

We do have full planning permission for the extension.

 

I don't know how the mortgage company would find out personally...But even then we'd just move the mortgage if it was an issue.

 

Just as an aside, how would the surveyors/conveyancers etc know that we've made any changes to the interior?

 

Thanks for your input on this.

 

Sounds to me like you've got everything covered UJ. Good luck with the project and I hope all goes well for you. I did the same thing about 18 months ago to my 1930's house. It was, um, fun!

 

re: your question, I don't think that conveyancers would know at all. They just pick up on planning apps and try to tie up the obligatory paperwork that should have been provided at the moment in time the work was carried out. Certainly Surveyors wouldn't be bothered about internal changes as they are employed to assess (very badly IMHO) the value of the house compared to the amount borrowed to purchase. I'm sure others will point out if I am wrong though. I wouldn't worry about the CDM changes as this will only likely affect large domestic projects, making them notifiable to the HSE. Small extensions are very likely to be exempt, but as Colonel says the exact details are to be confirmed.

[Unbelievable Jeff]

No probs.

 

As an addition to The Colonels list, make sure your insurance company is aware that you are having structural work done to your property.

 

Yeah, that's the only one I guess that may be tricky, do they need proof of building regs, or do they just need to know? Be worth ringing up and asking them I guess.

[Unbelievable Jeff]

Sounds to me like you've got everything covered UJ. Good luck with the project and I hope all goes well for you. I did the same thing about 18 months ago to my 1930's house. It was, um, fun!

 

re: your question, I don't think that conveyancers would know at all. They just pick up on planning apps and try to tie up the obligatory paperwork that should have been provided at the moment in time the work was carried out. Certainly Surveyors wouldn't be bothered about internal changes as they are employed to assess (very badly IMHO) the value of the house compared to the amount borrowed to purchase. I'm sure others will point out if I am wrong though. I wouldn't worry about the CDM changes as this will only likely affect large domestic projects, making them notifiable to the HSE. Small extensions are very likely to be exempt, but as Colonel says the exact details are to be confirmed.

 

It was such a bizarre house, we got a bargain on it due to that. A Victorian 2 up 2 down, with a 1980 extension (done well though, managed to make it look nice with hung tiles) of the same size next to it, but with no adjoining staircase, so had a spiral staircase in the lounge in addition to the normal staircase. First floor of the two halves therefore weren't joined. Its a shame I don't have the original floorplans as it's quite a weird one.

 

 

It's hard work with a 2 year old (she was less than 1 when we started), that's for sure, going alright so far though. You finished with yours now?

[Dimond Geezer]

Yeah, that's the only one I guess that may be tricky, do they need proof of building regs, or do they just need to know? Be worth ringing up and asking them I guess.

 

I built an extension on my place, like you at weekends & evenings, all I needed to do was inform them, they didn't ask for details, but did add 30 quid onto my premium.

[bridge too far]

Yeah, that's the only one I guess that may be tricky, do they need proof of building regs, or do they just need to know? Be worth ringing up and asking them I guess.

 

If ever you come to sell your house, you'll have to show paperwork / permissions for absolutely everything these days. When we sold our old house 2 years ago, we had to have all the certification relating to a simple replacement kitchen (gas cert. elec. cert). It's because these days you have to declare everything to your potential buyer's solicitor.

[Unbelievable Jeff]

If ever you come to sell your house, you'll have to show paperwork / permissions for absolutely everything these days. When we sold our old house 2 years ago, we had to have all the certification relating to a simple replacement kitchen (gas cert. elec. cert). It's because these days you have to declare everything to your potential buyer's solicitor.

 

And if you say you haven't changed anything?

 

We have gas and electric though, it's literally building regs (it'll mainly be insulation based)...

[bridge too far]

And if you say you haven't changed anything?

 

We have gas and electric though, it's literally building regs (it'll mainly be insulation based)...

 

Well if you say you haven't changed anything and then something goes wrong when your future buyers are in situ I guess they can sue you for non-disclosure. I already had gas and electricity in my kitchen - all the installer did was to move the location of the oven and replace a gas hob and install a kick-plate heater. But still I had to have the Gas and Electricity certificates.

 

My daughter is group compliance manager for a nationwide estate agent and she says solicitors are very hot these days on having proof of everything!

[Unbelievable Jeff]

Well if you say you haven't changed anything and then something goes wrong when your future buyers are in situ I guess they can sue you for non-disclosure. I already had gas and electricity in my kitchen - all the installer did was to move the location of the oven and replace a gas hob and install a kick-plate heater. But still I had to have the Gas and Electricity certificates.

 

My daughter is group compliance manager for a nationwide estate agent and she says solicitors are very hot these days on having proof of everything!

 

And that's fair enough, but when we sell our house we've already not got everything due to when the original extension was done. How would they prove you did the work as well? What happens if you have a house built in the 30's that didn't have sign off for Gas or electric due to the time? What do solicitors do then?

 

All the solicitors do is advise the seller to take out indemnity insurance for the new owner for any work pertaining to any issues.

 

With moving the location of the oven you have to move the cooker fuse and gas supply I suppose, which is pretty important.

Edited 18 February, 2015 by Unbelievable Jeff