New Extension, comments on costs estimated so far.....

I have planning permission for an extension, two storey behind garage and single storey above. The garage is attached to the side of the house and we are filling in the bit behind it.
The garage is just under 3m wide, the two storey section is approx 4m long and the garage is approx 6m long. We want a cut roof to maximise the storage space.

I have spend significant amounts of time calculating out quantities of materials and getting quotes from local Builders Merchants.

After having 6 different Builders visit to quote (Over a 3 month period because they never came back to me with prices) I have finally started to get some prices in. Although I only really want a price for sewage, shell inc roof and knock through's, one builder mistakenly quoted for all of it at £68,000!

Here's the breakdown I have estimated, assume each days labour will be for mimimum 1 tradesman + 1 labourer:-

Sewage & Foundations - 6m run and T into existing pipes (Up to 4ft down) and install inspection chamber. Dig out foundations with mini digger, dispose of soil. Pour foundations, install insulation etc.

Materials - £974.57 (Inc tips for soil, readymix concrete, DPM, hardcore, insulation & vapour barrier)

Labour - 6 days (with mini digger)


Walls - Build insulated cavity walls including removing some of existing garage wall, roof from garage etc. up to wall plate.

Materials - £3,768.88

Labour - 10 days


New windows and doors - For extension only

Materials - £1,527.66 (UPVC, mahogany out/white in to match existing)

Labour - 4 days


Roof - Cut std pitched roof with gable on end, 1m dormer on front elevation.

Materials - £1,276.75 (Existing garage tiles reused, inc 2 skylights)

Labour - 5 days


Knock throughs - Remove adjoining wall into kitchen and install RSJ(3m long), remove wall from kitchen to dining room and install RSJ (3m long), remove wall on landing and install RSJ(2.5m long)

Materials - £500

Labour - 3 days


Internal work - insulation, plasterboard, floorboards etc.

Materials - £2,063.57

Labour - £1,700 (Plasterer only, as I will do rest)


Electrical & Plumbing, fixtures - Inc kitchen, shower room.

Materials - £6,785.30

Labour - 1 day (Sparky to check and test my work)


New boiler

Materials & Labour - £2,000


Paint, floor coverings etc

Materials - £1,284.00


There are a few minor items I have missed of but the total cost estimated is:-

Materials - £23,000 (Inc boiler install)
Labour - 29 days
Plasterer - £1,700


With a builder at £200 a day inc labourer this would be £23,000 + £5,800 + £1,700 + VAT = £ 35,837.50

Does this all sound reasonable or am I being shortsighted?

Any comments welcomed as I am hoping to project manage and do as much as I can myself (Even though it will take a LONG time!)

I have very detailed spreadsheets if anybody wanted to take a further look.

As a rough guide £1000/sq m, so the first quote of £68k may be closer to the mark.
Unless your getting a fixed cost, i would over estimate the labour cost by 50%.
Who is installing the first and ground floor structure? Also where is the cost for temp works (scaffolding/strongboys etc)? Are lintels covered in cost?

As you are project managing, you may be better off getting an electrician and plumber to quote some of the items.

I have allowed £850 + VAT for scafolding. (Telephone quote)
Concrete floor is included in costs, floor joists would be installed by builder as shell progressed. Again I have included lintels and cavity closers in materials.

Are you of the opinion that my labour estimates are overly optimistic? (Work wouldn't start until March time so the days would have gotten longer again)

I am waiting for a quote, it is for a faimly builder who has father and two sons brickying and 1 labourer. All 4 for just over £400 a day + VAT.
They are happy for me to supply materials (Obviously at the right time, type and quantity) Does that sound reasonable?

Are they Polish @ that £..............have they got any customers you can talk to

I came across them doing some serious extension/reconfiguration work on a bungalow I drive past every day. I stopped and had a chat to the guy and he has been to have a look at the plans/work.

Bear in mind I live in a rural area (Herefordshire) so I would hope labour rates were significantly lower than some areas of the UK!

If his quote sounds reasonable it will be easy to pop in to see the householder to see what he thinks of the work so far.

What do you think is an average labour rate in my area?


You shouldn't joke about Polish workers , we have a massive migrant Polish/Eastern Block workforce that descend on us through the summer as we have one of the largest UK Strawberry growers just down the road

Well 29 days is about 6 weeks, that seems very optimistic for a project that size.

Hi Static

Thanks for your comments.

Bear in mind that it would be 6 weeks for the shell only. Single sewage pipe join, foundations for a 3x4m area. Strip roof off garage, build double skin shell on 1st floor and 2nd floor inc above garage. Then build cut roof and knock through into existing property.

If you take a look at my breakdown in the first post, are there any particular areas that you think I have underestimated on?

Almost all builder who have been round seem to think it would take 4-6 weeks to do the shell only.

£44,000 inc. vat would seem fair.

£1000/m was right about 6 months ago but I am finding quotes are coming in about £1200/m at the moment.

£400/day for 4 men is ridiculous. They can't possibly have insurance or be paying proper holiday pay, welfare, etc. at those rates.

The builders probably didn't come back because you frightened them off. No builder I know would work for an amateur project manager. Don't take this the wrong way, I'm just telling it like it is.

If you asked me for an estimate I would be telling you 1200 per m2 inclusive of VAT
Your labour rate is far to low work like this you can figure on being 50% materials 50% labour with labour coming in at 60% on some jobs
You have all your on costs to add to that. supervision insurance scaffold Plant etc etc
Budget on 60k to finish the job

Hi

Thank you all for the comments.

Please bear in mind that I am looking to complete a lot of the internal work myself, partly because cost is an issue, partly because I can and partly because I will enjoy it!

The costs per m that you are quoting are obviously finished costs, I hope to be lower that that by doing the work myself.

My original post was primarily showing my breakdown of materials and labour (per day).
Can any of you comment on the amount of time I have allowed per job and the material figures?

I appreciate the comments on the £400 daily rate, I will obviously treat this with caution.

I have had another quote back for the shell:-
Drains + clear site - £1,500
Footings up to DPC inc foundations - £2,000
Scafolding - £1,400
New external/internal blockwork - £10,700
First Floor joists - £800
Cut roof - £2,700
Felt, batten, tile roof inc 2 x Velux - £4,000
New windows/doors - £2,800
Remove 2 external walls, 1 internal - £2,200

TOTAL £28,100 + VAT = £33,017


How does this sound?

noseall said:

£44,000 inc. vat would seem fair.

Click to expand...

Can you break that down at all?

Is that with me doing most of the internal work?

You want to try living in Sussex Lowest wage rates in the country with the highest cost of living outside of London ....FACT...Prosperous my arse .......just for the lucky few

I'm not sure that this will be of any use as a comparison, not least because I live in the SE.

I've just had an extension done that was exactly the same dimensions as yours, with the addition of a single storey right the way along the back of the house as well. I put in the foundations / floor slab and got builders in to complete a water tight shell.

So bearing in mind that;
i) I had to have the garage section built.
ii) I had the single storey across the back.
iii) I had completed the foundations and floor slab
iV) I supplied and fitted the windows

total was £35,000 inc. I'd say that with the inclusion of a new boiler, plumbing and electricals you're going to be closer to noseall's figure.

As for timescales, it was quoted at 9 weeks, but took 13 due to some shockingly bad management of the subbies by the Builders.

Project Plans and budgets:

Include 33% for contingencies
and 10% for cost inflation
and 10% for wastage
and 10% for bad weather
and 15% for builder not coming in when he's got a hangover or a cash job somewhere else
plus another 50% just in case.

With experience of similar jobs you may vary these figures.

(p.s. I am a Project Manager by trade. Not for house builds, but this advice is seriously meant. Things happen.)