Pricing from surveyor

ryanrod

I am planning a dormer extension to my existing bungalow.

I am currently getting prices from builders.

I have gotten in the first price, but have a fundamental question to ask.

The footprint of the extension is 7m x 13.8m with 300mm cavity walls external 3 sides. The first floor is a dormer with usable living space of
8m x 6.7m (gross floor area).

So by my reckoning the
Ground floor area is 6.7m x 13.2m (ex walls) = 88.4m
First floor area is 6.7m x 8m = 54m

At the top of the surveyors document is
New Ground floor area = 7m x 13.2m = 92.4m2
New First floor area = 7m x 13.2m = 92.4m2

So the surveyor reckons the first floor at the same size as thegroung floor
and takes the external measurement of on wall and internal measurement of the other wall?


Can anyone tell me if this is normal practice for pricing? I don't want to go back to the guy telling him he is wrong if this is normal practice.

I always thought floor area was calculated on internal usable floor space of
a dwelling.
Now the prob with the pricing is these increased values perculate
through the document and increase the price a lot!

Builderfromhell

I have always measured form inside of external walls to get floor area. Also, I do not measure stairs area twice. That is, if I have measured it on Ground floor I include 50% of it's area only when measuring 1st floor. atrium areas are only measured once. This is how I have been doing for over 25 years and would be interested to know if I have been wrong.

kkelliher

Different people do it different ways.

Commercial buildings are always measured to the outside of the building when discussing costs whereas Residential buildings are normally to the inside. Depending on how he has calculated his costs on similar projects could be why he calculates it this way. It is in practice much easier/quicker to tape the outside of a building than the inside.

For a one off building (in your case 4m2) the difference is nominal. You would expect to bargain well over the effect this has on cost.

ryanrod

Fair enough inside or outside makes little difference in floor area calculation,

But for the upstairs dormer area would you include the roof space that
is not habitable i.e 13.8 -8 = 5.8m2 x 7m = 40.6m2.

Thats 40% of first floor approx being included in calculations thats
not actual floor area (to either side of min usable height).

thanks for your comments

ircoha

ryanrod wrote: »

Fair enough inside or outside makes little difference in floor area calculation,

But for the upstairs dormer area would you include the roof space that
is not habitable i.e 13.8 -8 = 5.8m2 x 7m = 40.6m2.

Thats 40% of first floor approx being included in calculations thats
not actual floor area (to either side of min usable height).

thanks for your comments

To follow your link of thinking would require a second price, which is the cost of building 'un-inhabitable' space that still requires joists, insulation, ceiling on underside etc, which would lead to all sorts of confusion. In ur case it is 40% : could be different

The other question that arises is what bit of the building, in your opinion, should carry the cost of the roof over the un-inhabitable space?

The practice of measuring internally for residential is usual because the residential planning rules are on internal sizes for areas.

The way he has done it is a mix of internal and external which is prolly to take an average.

If you are willing to pay him, he will price each item down to the cost of fitting each light switch: it will cost you.

In passing is the cost of each area the same per sq metre?

Is there a new stairs?

One way of finding out more about his thinking is to say, okay we now only want the 2 storey shell and no habitable space upstairs.
Good hunting:pac:

ryanrod

ircoha
[In passing is the cost of each area the same per sq metre?]

Yes, at the end of the document is cost per sq metre, this appears to be
based on Total cost / ground footprint x2 (in ft2)

[Is there a new stairs?]

There is new stairs but will be in existing house.


[One way of finding out more about his thinking is to say, okay we now only want the 2 storey shell and no habitable space upstairs.]

good idea, will be getting pricing from others also.


My confusion really lies with the square foot price.
When people talk about square foot price they are (to my mind) talking about
total cost of build / internal gross floor area.

So his square foot price looks good because he uses
Total cost / ground footprint x2 (in ft2) but when you use standard

total cost / gross floor area it's his cost per sq foot increases by 26%.

I kind of feel he's trying to make price look more attractive than it
actually.

ircoha

ryanrod wrote: »

ircoha
...
My confusion really lies with the square foot price.
When people talk about square foot price they are (to my mind) talking about
total cost of build / internal gross floor area.

So his square foot price looks good because he uses
Total cost / ground footprint x2 (in ft2) but when you use standard

total cost / gross floor area it's his cost per sq foot increases by 26%.

I kind of feel he's trying to make price look more attractive than it
actually.

Lies, damn lies and statistics:)

Dont get hung up on the cost per square foot when the big number, ie total cost, is the important thing.

If all the calcs from different builders are not done the same way the the per sq foot number will be different but the big number is what matters.
As I said already if he was asked to price up a detailed bill of quantities it would give you a better idea of how the big number is arrived at,

Don't get me wrong, I do see ur dilemma and even though the difference is area is (only) c 5%, at 3k/sq meter that is still 15k, which is less than my fee for this post:)

ryanrod

Can't argue with you there, more prices is the way to go.

sinnerboy

ryanrod wrote: »

I am planning a dormer extension to my existing bungalow.

I am currently getting prices from builders.

I have gotten in the first price, but have a fundamental question to ask.

The footprint of the extension is 7m x 13.8m with 300mm cavity walls external 3 sides. The first floor is a dormer with usable living space of
8m x 6.7m (gross floor area).

So by my reckoning the
Ground floor area is 6.7m x 13.2m (ex walls) = 88.4m
First floor area is 6.7m x 8m = 54m

At the top of the surveyors document is
New Ground floor area = 7m x 13.2m = 92.4m2
New First floor area = 7m x 13.2m = 92.4m2

So the surveyor reckons the first floor at the same size as thegroung floor
and takes the external measurement of on wall and internal measurement of the other wall?


Can anyone tell me if this is normal practice for pricing? I don't want to go back to the guy telling him he is wrong if this is normal practice.

I always thought floor area was calculated on internal usable floor space of
a dwelling.
Now the prob with the pricing is these increased values perculate
through the document and increase the price a lot!

query the surveyor - he will not mind what is a reasonable question .

the m2 should be along inside of external walls - so in case of dormer should exclude the un usable space . the stairway should be measured on both floors UNLESS there is a big ( 5m2+ ) balcony type landing . only exclude upper space in that case .