Having trouble comparing quotes and understanding whats reasonable

[vab89]

Hi all

 

new to this forum & apologies if this is wrong section (costing & estimate sub seemed more to do with actual build).

 

We want to add a double storey self containned 30sqm side extension (ie 15sqm each floor) to our house (SE London conservation area) by replacing existing garage structure. Nothing fancy but ideally a separate entrance (but no new address, same utilities etc) with kitchenette, toilet, shower etc. No neighbours to the side of the building within 5-10m and plenty of space so dont expect any issues on that front. only potential issue is a TPO tree that is in the corner of the garden 

 

I've contacted several architectural / design & build agencies to get the quotes for what it would cost from start to finish before the actual work gets done (ie planning,architectural, structural, building control) and have received some widely diff quotes. Appreciate some arent as inclusive and dont include the PM element but either way its hard to compare. Was hoping to get some advice on whether to go for the more expensive ones as they are all in vs the cheaper ones which might actually end up costing roughly same once all is considered:

 

Option 1 (highly recommended on local FB group, featured in various publications such as: "Your Property Network, Inside Property Investing, Best of Houzz Design, Archant etc): £8.3k inc. VAT 

All in package including: Measured Site Survey of Proposed Project area; Design Concept and Development Drawings with Revisions; Drawings and Planning Application Submission to Local Authority, Certificate of Lawful Development, Prior Notification etc. *Planning Fee Inc.; Structural Calculations/Drawings; Building Reg. Drawings - excluded, PM - 10% of build cost.  Assuming 1.5-2k / sqm shell build cost + outfitting 20k  = 6.5-8k PM costs all in cost 15k - 17k? 

 

Option 2: (highly recommended in local FB group): 

All in package excluding local authority costs and structural engineer (but fixed PM costs): £10k (inc VAT) + 1.2k planning / building reg app costs + structural engineer (1.5k?) = £12.3k estimate cost.

 

Option 3: South London Architectural design firm: 

Only ones to do on site visit. Got really good vibe from him. Boutique 2 person firm operating for 15 years, Liverpool grad, c.8yrs experience before own firm. £1.7k+VAT fee for architectural design/planning application submission. Planning submission costs excluded. Assuming 1-1.5k + VAT for building reg & structural engineer each that would take us to £4.5-6k in fees + planning submission costs of £1.2k...

 

Option 4: Small new firm based in same LA (with public site/location to walk in & chat etc)

young firm, <2years, director in touch has civil engineering background (however think hes just BD / PM. appears they have structural engineers etc do the work). lots of reviews on google but i wonder how "real" they are. much more than ive seen for other firms that have been around and i know have organic positive feedback e.g. local facebook group. keep playing up the fact that they arent VAT registered, have trade discount deals etc. quoted £1.5k for planning/architectural design & submission then on top of that c£800 for building control and technical design (ie structural etc). Not sure how to evaluate / judge it. The lower price might make sense for perhaps those dealing with less high end Projects... 

 

Should i keep looking? i feel option 1-2 might be a bit too much for what is a simple project imo. similar firms have had  their extensions featured in newspaper articles for stunning design etc and honestly were not going for that. we just want a side box extension...nice and simple...i like the fact that option 3 came on site, even if we need to book everything seperate atleast were not liable for big chunky 6-8k fee even if unsuccessful application (e.g. option 1 essentially paying 75% excl PM no matter what)...but scared that without any PM oversight we might run into issues...

 

also a more general question...is it realistic to get a self contained side extension with seperate entrance assuming its for grandma who currently lives in main house? no separate address, no seperate utilities etc...but want the privacy of seperate living. it wont be any where near the minimum reqs for studio/1bedroom flat (36-39sqm i believe)...or would our only option be to do the side extension and also have a porch extension so that it has 2 seperate entrances to main house & side extension? 

 

Finally more of a design / cost question - were currently thinking 30sqm, 2 seperate floors and budgeting e.g. 1.5-2.5k + VAT for that. Would the cost be lower if we went for e.g. 20 sqm 1st floor but elevated height & essentially had a mezzanine/loft/"entresol" type 2nd floor, something like this:

 

 

 

our desired max budget is prob around £120k. would be great to understand if this is a bit of a pipe dream. 

 

many thanks for any help / advice suggestions. 

[JohnMo]

Trouble with Facebook reviews you have zero idea what they wanted as a client. Are they real - who knows.

 

First you need to be able to talk with the architect, bounce your and his ideas off each other, freely. 

 

I sacked my first architect, because they were closed off as far as design went (all in one package), they saw everything I wanted, a waste of time, and no value etc, so stand up row later and we went different ways. Second one completely different, he was an architect and that's all he did, not interested in project management, which suited me fine. However the above wasted 6 months.

 

If you want standard no frills to building regs only, all in one may be ok, anything different, any bells whistles, move to someone else.

 

If you see any reviews where there is mention of them being difficult or closed off, take that as a clear warning to move on.

 

Option 3 looks fine, gut feeling says a lot. But small firm could be pulled in all directions, which is ok as long as you build this in to expectations on timescales.

[Russell griffiths]

Put up a pic of the house and a sketch of where the extension is to go. 

My initial thought is £120 isn’t enough.

And if that is your budget then why would you give £15 grand away to project manage it.

And why would you spend £10 grand being told you don’t have the budget.

 

Get a small local architectural technician  to do some very brief outline plans £5-600 max, ask 2 local builders to have a look and give you a ball park figure. 

 

If all is is good then go further. 

 

That is a small project and budget to spend that much on overseeing it. 

[saveasteading]

Ditto. Russell is right.

Another option is to start with a quality, small, local builder. They can give an immediate guesstimate, and can get the necessary construction details within their package.  

Assuming you are looking at standard materials, as what you've shown is a bit flash. And as with all grand designs and architect mags no handrail "yet".

 

£120k? In theory yes. In practice you'll be lucky.

 

[vab89]

Hi all

thank you for your response. 

Ive been told that its useless to try and come up with builder estimates as they can only guess until they see the structural / architectural / building control drawings and i suppose on one hand it make sense but on the other hand i suppose it could also be a ploy to get the sale done. 

 

in terms of pics see attached. goolge images since havent really got any personal ones on hand but they give an idea - its a cul de sac, 1990s build development. those massive trees you see are TPOs. ive outlined in red box where we want to knock down garage and replace with side extension. the frontal image of the house is actually our neighbours (the one in the middle) but it looks exactly the same (their garage is the one attached to ours, ours isnt).

 

in terms of £120k budget being potentially small..assuming 6-7k in total architectural/building control/structural / application fees, 25k for fittings (kitchenette, shower, etc), that leaves around 2.5k + VAT per sqm. is it much higher than that? 

 

should we be budgeting 3-4k?

 

and any thoughts on potential cost of e.g. 20sqm 1st floor + mezzannine vs 30sqm 2 storey? or is that more suited to another sub forum here?

 

many thanks all! 

[saveasteading]

23 minutes ago, vab89 said:

useless to try and come up with builder estimates as they can only guess until they see the structural / architectural / building control drawings 

Yes and no. If this is going to be traditional construction then an experienced builder knows the approximate cost level, and detailing is simple.

But, there is no money in giving free advice so some trust is required both ways.

From my own experience I would visit most potential clients and advise an approximate cost immediately, or next day. But some I simply declined on a whim or immediate judgement.

I don't know you or your local builders so can't  predict how it might go.

[Bozza]

Take, with a pince of salt, anything you read online, especially social media reviews such as on FB.  It’s incredibly easy for a rubbish businesses to establish a positive social media presence online.  People get paid to write fictitious reviews and content.

 

do proper vetting, companies house check, visit prior clients etc.  good businesses will be happy to provide proper reference etc .

 

 

 

 

 

 

 

 

 

 

 

[vab89]

22 minutes ago, Bozza said:

Take, with a pince of salt, anything you read online, especially social media reviews such as on FB.  It’s incredibly easy for a rubbish businesses to establish a positive social media presence online.  People get paid to write fictitious reviews and content.

 

do proper vetting, companies house check, visit prior clients etc.  good businesses will be happy to provide proper reference etc .

 

 

 

option 3 has been very open about letting us get in touch for references and his firm has been on companies house since 2010 (micro accounts)...no social media presence...so def not juicing anything....option 4 only since Jun 23...soit sounds like option 1-2 is prob too rich for this type of project, option 4 probably a bit sketchy / inexperienced so option 3 the best....ive looked at my local community facebook group to get some recommended builder recommendations and the first 2 i called said theyd be happy to give high level initial estimate based on some descriptions / pictures so guess ill do that too to see how realistic budget is...

 

i saw this picture before and i think it was very helpful...i suppose a £1.7k+ vat design fee makes sense based on this...not sure what the £1.2k "specification / schedules/tender prices" bit is, but suppose the £1.5k-2.25k covers things like building control and structural engineer drawings...so again makes sense....question is whether we need the delivery bit for £4.5k (and sounds like much more in the quotes we received)...and based on responses here sounds like no...

Edited December 20, 2023 by vab89

[Kelvin]

I would think the difference in cost between single storey + mezzanine and two storey marginal. Clearly your budget sets your ultimate build but don’t compromise on such a big element so early. If you really want two storey stick to that for now.
 

References are great but they only go so far. For example, we went to see three Hebridean Homes builds before deciding to go with them. The feedback was mostly positive with the negatives being consistent but nothing to worry about. All three loved their finished houses and they did look good. Our experience of them has been pretty awful by comparison. 

[twice round the block]

Option 3 sounds good to me. At least they managed a site visit.

No much in the construction costs between two storey and mezzanine as a third of your money is in the ground with footings and services.

[nod]

If your budget is 120 Then you b need to cut your cloth accordingly 

Blowing a large chunk on fees is madness 

A good building contractor will manage themselves 

 

Weve spent under 7k on all design planning apps and and professional feed on. 6 bed new build 

We kept it under four on our previous build 

 

Draw out what you want and have a Architect convert it into workable drawings 

[Russell griffiths]

Now we have seen some pics, I am completely split in two different directions on this. 

 

1.. you stand absolutely no chance of getting planning that close to those trees, trying to convince the planning is one thing, but getting a foundation system designed that the tree officer agrees to is another thing. 

Then you have the cost, to get a system designed that will hold the extension up but not effect a tree with a TPO on it will be pretty expensive. So it could stop everything dead in its tracks. 

 

 

2. The tree was there when the original house was built, so we can presume the house foundation was designed around the tree(s). 

So maybe the garage sits on a very well designed foundation also, in this case you might have crossed some very awkward bridges already. 

If this is the case you can argue that all the work in the ground has already been done, there is already a single storey structure there, so going up another few metres isn’t going to hurt anybody. 

 

I think i would proceed with a lot more research 

go and find any original planning documents for the house, try and find anything relevant to foundation design. 

 

Get a local builder/ landscaper to dig a couple of trial holes to try and confirm what sort of foundation the garage sits on. 

If the foundation is acceptable for a two storey structure then proceed with getting some simple plans done. 

If the foundation is not up to par then I think this idea could be dead right now.

As you could spend  many thousands getting consent only to find that you then need to chuck £30,000 in the ground for a foundation system.

 

To end up with only 30 sq metres of liveable space, it’s not a lot for your money.  

[vab89]

2 hours ago, Kelvin said:

I would think the difference in cost between single storey + mezzanine and two storey marginal. Clearly your budget sets your ultimate build but don’t compromise on such a big element so early. If you really want two storey stick to that for now.
 

References are great but they only go so far. For example, we went to see three Hebridean Homes builds before deciding to go with them. The feedback was mostly positive with the negatives being consistent but nothing to worry about. All three loved their finished houses and they did look good. Our experience of them has been pretty awful by comparison. 

 

43 minutes ago, twice round the block said:

Option 3 sounds good to me. At least they managed a site visit.

No much in the construction costs between two storey and mezzanine as a third of your money is in the ground with footings and services.

 

thanks for response. i think part of the reason for thinking about mezzanine approach is that ideally the floor space would be 18-20sqm downstairs for kitchennette/shower/toilet/living space and 10-12ish upstairs for bedroom, however if going for standard 2 storey, 20sqm x 2 is just above the limit for something to be potentially considered seperate dwelling and we didnt want council to think that thats the cheeky backdoor route were going for....but at same time 15sqm x 2 seems kind of unbalanced for the 2 floors...just a bit too small potentially on the ground floor and a bit too much on upper...but well need to double check. we actually have a garden office that i THINK is 3x5 so is good reference...but it actually might be 3.5 width...been a few years now.  

 

16 minutes ago, nod said:

If your budget is 120 Then you b need to cut your cloth accordingly 

Blowing a large chunk on fees is madness 

A good building contractor will manage themselves 

 

Weve spent under 7k on all design planning apps and and professional feed on. 6 bed new build 

We kept it under four on our previous build 

 

Draw out what you want and have a Architect convert it into workable drawings 

 

7k inc VAT and the application fees? if so thats about 4.6k for architectural / structural /building control etc....which seems to fall in line with what we might be facing (or slightly more expensive by 1k ish)...do you think for this project it should be much lower? it seems the architechtural / design is appropriate quote at around 1.5-1.7k....should we be aiming lower for structural engineer / building control? we havent sourced any quotes for that yet individually so just guesttimating that it would be between 1-1.5k too...

 

9 minutes ago, Russell griffiths said:

Now we have seen some pics, I am completely split in two different directions on this. 

 

1.. you stand absolutely no chance of getting planning that close to those trees, trying to convince the planning is one thing, but getting a foundation system designed that the tree officer agrees to is another thing. 

Then you have the cost, to get a system designed that will hold the extension up but not effect a tree with a TPO on it will be pretty expensive. So it could stop everything dead in its tracks. 

 

 

2. The tree was there when the original house was built, so we can presume the house foundation was designed around the tree(s). 

So maybe the garage sits on a very well designed foundation also, in this case you might have crossed some very awkward bridges already. 

If this is the case you can argue that all the work in the ground has already been done, there is already a single storey structure there, so going up another few metres isn’t going to hurt anybody. 

 

I think i would proceed with a lot more research 

go and find any original planning documents for the house, try and find anything relevant to foundation design. 

 

Get a local builder/ landscaper to dig a couple of trial holes to try and confirm what sort of foundation the garage sits on. 

If the foundation is acceptable for a two storey structure then proceed with getting some simple plans done. 

If the foundation is not up to par then I think this idea could be dead right now.

As you could spend  many thousands getting consent only to find that you then need to chuck £30,000 in the ground for a foundation system.

 

To end up with only 30 sq metres of liveable space, it’s not a lot for your money.  

 

ill post a pic tomorrow morning but it think its a bit misleading. the tree is massively tall but the actual crown covering everything is super high up. the lower branches would just barely touch a proposed 2 storey development and if it was a 1.5 storey mezzanine approach i dont think it would touch at all. weve previously had successfull application to trim the branches before. 

 

when you say original planning for documents, would that have been likely part of the docs given to us when we bought house? or in land registry or something? 

 

great idea on the foundation stuff. how much would such an exercise cost usually? is there any point involving a tree surgeon before going through with the planning / architectural design? would they be straight up and say "nah this wont be an issue from a branch POV if the foundation is ok" or would they still try and get engaged on a £500 tree report either way? i suppose it would help any application to include it either way so wouldnt hurt? 

 

many thanks again for everyones response 

[Bozza]

“the tree is massively tall but the actual crown covering everything is super high up. the lower branches would just barely touch a proposed 2 storey development and if it was a 1.5 storey mezzanine approach i dont think it would touch at all. weve previously had successfull application to trim the branches before.”
 

So what is important is the TPO tree Root Protection Area.  Measure the diameter of the trunk 1.5m from ground, then times that number diameter by 12.   Measure that calculation as a distance from the tree trunk, 360degrees That’s the circular RPA that you normally cannot disturb or dig and basically isn’t in play.   If your proposed extension is within the RPA you’re very likely stuffed at least with dug foundations.  And unlikely to be able to take materials, machinery across that RPA either.

 

I have trees and know this because we had to build around the RPAs.   And our trees weren’t even TPO’d.
 

 

 

[Mr Punter]

Depending on the soil type you may well need to budget for piling.  If you can have a discussion with the local authority building control they may be able to give you a steer with zero cost.

[ETC]

Don’t forget about VAT.

[Russell griffiths]

 Somebody tell me if I’m wrong 

but you can forget having a mezzanine area as a bedroom, without a fire escape route not including those stairs you wont get building control sign off. 

 

I think you need to decide what this space is for. 

 

 

Edited December 20, 2023 by Russell griffiths

[vab89]

50 minutes ago, Bozza said:

“the tree is massively tall but the actual crown covering everything is super high up. the lower branches would just barely touch a proposed 2 storey development and if it was a 1.5 storey mezzanine approach i dont think it would touch at all. weve previously had successfull application to trim the branches before.”
 

So what is important is the TPO tree Root Protection Area.  Measure the diameter of the trunk 1.5m from ground, then times that number diameter by 12.   Measure that calculation as a distance from the tree trunk, 360degrees That’s the circular RPA that you normally cannot disturb or dig and basically isn’t in play.   If your proposed extension is within the RPA you’re very likely stuffed at least with dug foundations.  And unlikely to be able to take materials, machinery across that RPA either.

 

I have trees and know this because we had to build around the RPAs.   And our trees weren’t even TPO’d.
 

 

 

 

hi thank you very much for your post. this is very insightful. the architects did bring up potential concerns about TPO trees but never mentioned this thing specifically. ill have a quick measure tomorrow (as well as post the pic) but id hazard a guess that the outer most edge would def. be within 12x the diameter of the tree.

 

so i suppose that means that its much more likely that a single storey would make most sense as presumably the existing foundation should be good enough as the structure wouldnt be much different from the garage in footprint (although potentially would get closer by 1m sideways) but shouldnt need to go "down" as much.

 

my concen for single storey was that potentially that it might fall foul of the whole "keeping same look and feel of the area". as you can see from the pic i posted its quite a boxy house and im wondering whether single storey might just look a bit naff? suppose if the tree roots would be the issue then probably not much choice either way in the matter...unless the foundation req. would still likely be more than what we have? 

 

so would the recommendation be first to speak to a tree surgeon to determine how far the likely roots go or is the RPA set in stone no matter what? and then after that ask builder to dig some holes to see the type of foundation there is to determine if its good enough for 1 or 2 storey? in any case i think the footprint might need to be expanded as from memory the garage is under 3m in width...

 

thank you again for your informative response.

[vab89]

1 hour ago, Mr Punter said:

Depending on the soil type you may well need to budget for piling.  If you can have a discussion with the local authority building control they may be able to give you a steer with zero cost.

 

thanks for the pointer. i suppose this sounds like a separate issue to the root problem. are you saying the council would have data on the type of soil in the area that they may be able to share that i would then be able to bring up in any convo with the builders?

 

43 minutes ago, Russell griffiths said:

 Somebody tell me if I’m wrong 

but you can forget having a mezzanine area as a bedroom, without a fire escape route not including those stairs you wont get building control sign off. 

 

I think you need to decide what this space is for. 

 

 

 

thanks for raising this point. wouldnt this be the same issue with a normal 2nd storey floor or no? would some sort of exit window with drop down ladder or something not work? tbh struggling to think how we would escape from the current house if say the stairs was on fire...the window design is quite hard to fully open and even then its a straight down drop to ground floor...

[saveasteading]

5 hours ago, twice round the block said:

No much in the construction costs between two storey and mezzanine

But...as a rule of thumb I say that a single storey building costs the same, per useful m2, as 2 storey.

 

This doesn't apply for a very small area though, as the stair takes up so much space. on one or both floors depending on arrangement.

Miss out the stair and mezz, save 1/4 of your cost, and lose ...not an awful lot of floor.

This means nothing of course if it doesn't provide the accommodation you want.

[BadgerBadger]

8 hours ago, vab89 said:

So would the recommendation be first to speak to a tree surgeon to determine how far the likely roots go or is the RPA set in stone no matter what? 

 

It's a bit more specialist than a standard tree surgeon you might find in the yellow pages, try googling a arboculturist tree survey to get along the right lines.

 

You will need a tree survey for planning, it was one of the first things we got before starting design, so could look at getting it done now so the arboculturist can properly advise you.  The circular RPA is a good starting point, but there is some variation, and the presence of your garage foundation will have influenced it.  I'm going to guess the garage was built on the edge of the 12x diameter circle in the 1990s, and the tree has continued to grow since.

 

Either way, I think you're in for an easier ride to try and stick with the existing garage footprint as expanding further sideways into the RPA is going to be tricky.

 

This could be a good thing to quiz your architects to help you decide as it's going to be a big theme of any design/application.

Edited December 21, 2023 by BadgerBadger

[Kelvin]

It seems a big expense for a relatively small space. 

[Marvin]

Hi @vab89

 

I have done a bit of digging....

 

My way of approaching your plan would be to check out the following personally before getting involved with Architects and builders.

 

The major obstacles of concern for me would be:

 

Planning: When I have been involved with extensions involving a separate access they were denied and access had to come via the main front door....!! 

 

Conservation rules: What are they? I think you will need planning permission. Check for an Article 4 Direction (A4D) which is part of planning legislation that allows the council to remove permitted development rights including changes of use from an area or a particular property in certain limited situations where it is necessary to protect local amenity or the well being of an area.

 

Look at web site, link below, and scroll down to the bit titled: Do I need planning permission to carry outworks to a house in a conservation area?

 

https://urbanistarchitecture.co.uk/how-to-get-planning-permission-in-conservation-areas-in-london-and-the-uk/#:~:text=Basic single-storey rear extensions,build one under planning permission.

 

Check previous planning applications in your area: A similar application was permitted in your area, however no front door and no second story: Use this reference 22/04965/HSE

 

https://publicaccess3.croydon.gov.uk/online-applications/   

 

 

TPO: As others have said if you need to do works near a tree with a TPO, be it access requirements or foundations or drainage, this can be expensive.  With limited knowledge of your home and grounds I would make the assumption that piling would be the only way forward IF a change to the existing foundations were required. However access and space for the equipment become a challenge...

 

 

Drainage: Where does the rain water go? Sewer? soakaway?  Will the work involve digging more holes in the ground??

 

I'm only being Mr negative to try and save you money.

 

Good luck

 

Marvin

 

 

 

 

[saveasteading]

50 minutes ago, Marvin said:

piling would be the only way forward 

1. Expensive for a small building.

Would create a potential stress point between old and new, as the existing building will continue to move and the new one won't.

 

2.For all that I have my doubts about them, steel screw piles to similar depth as the existing founds might work.

 

3. Sometimes you have to accept that an idea is not feasible.

[ETC]

Use the garage as a base and build up to create the second floor. If you don't want a new postal number then it will be an extension rather than a granny flat. The planners may query the use and might worry that you are creating a separate dwelling but if you explain that it is an extension to your home with a connecting door to house a family member independently they should be OK. It can get messy if they think you are trying to create another dwelling.