Cellar conversion - Kent

jc808

Background:

Existing cellar (between 6-7 feet existing headroom, rough stone floor, 500sq feet across 4 rooms., standard terrace)

quote for turning into a habitable space:

1. Basement centre wall removed and steel provided (on upstands)
Basement mid wall removed and steel provided (on upstands)
Ground floor centre wall removed and steel provided (on upstands)
Support chimney breast in kitchen with steel
Concrete support pad (full width) provided in cellar
............£12,981

2. Replacing short/ rotten joists in cellar (5 no)
...................£550

3. Enlarge lightwell at front of cellar
..................£800

4. Lower floor in cellar and provide new solid floor NB floor to be lowered to depth of existing foundations - not below as this will entail underpinning - and is to be poured in one operation plus stairs
...................£25,075

5. Tanking membrane on walls, then block work lining connected to existing wall via wall ties and concrete upsatnds
...................£19,802



I think this is really very expenisve - the steels/ upstands/ padstones in floor (£12k) joists (500) and lightwell enlargement (800) seems about right (Steels maybe a bit expensive poss - im no expert) but the final two parts - wow. I understand theres digging involved plus insulation/ hardcore/ screed but still...

And how can a non-load bearing, non-retaining block wall (with tanking and wall ties, granted) come to £20K?

Is this price too high?
If you need any more info I can provide

jc808

This doesnt include plastering/ finishing/ electrics btw

ormus

thats more than my semi detached house cost, 12 yrs ago.

bosseyed

Bloody hell! Thats does seem expensive just for the 'basic' building work, but don't forget it is a big, big job.

What about everything under the floor when they dig down to deepen the cellar? How far down are they going? depending on the amount of material to be removed, theres disposal costs to take into account. You've also probably got water mains, drainage pipes, gas mains etc under there, so you'd need all the LA survey info, possible drainage surveys etc to confirm the run and invert levels. Moving a gas meter/intake is flippin expensive I believe - presumably that price excludes all the preliminary investigative work?

Only thing to suggest is get a lot of quotes in and see how they tally I suppose, then you'll have more of a comparison.

My boss did a similar thing in his london house - extended and deepened the existing cellar etc, total bill was around the £180k mark..... :eek: In your case, I'd have to ask if spending £60k on another room will ultimately be worth it.

Edit: And don't forget you'll need to get party wall consent for your neighbours which can be pricey, extending the lightwell means planning permission is probably required - plus building regs will be required for the actual creation of the basement space, ie ventilation, fire escape routes etc. Like I say, big job that needs a lot of thought.

Double Edit! Does the price include for any kind of structural engineer? You'll need calcs from them to give to building control for a job like this.

Ultra Edit! Interesting link here. London biased, so not all of it may not be applicable, but theres some interesting bits about what you need to consider beyond just the basic building work. As I keep harping on - Big job! http://property.timesonline.co.uk/tol/life_and_style/property/interiors/article2875418.ece

jc808

bosseyed wrote: »

Bloody hell! Thats does seem expensive just for the 'basic' building work, but don't forget it is a big, big job.

What about everything under the floor when they dig down to deepen the cellar? How far down are they going? depending on the amount of material to be removed, theres disposal costs to take into account. You've also probably got water mains, drainage pipes, gas mains etc under there, so you'd need all the LA survey info, possible drainage surveys etc to confirm the run and invert levels. Moving a gas meter/intake is flippin expensive I believe - presumably that price excludes all the preliminary investigative work?

Only thing to suggest is get a lot of quotes in and see how they tally I suppose, then you'll have more of a comparison.

My boss did a similar thing in his london house - extended and deepened the existing cellar etc, total bill was around the £180k mark..... :eek: In your case, I'd have to ask if spending £60k on another room will ultimately be worth it.

Edit: And don't forget you'll need to get party wall consent for your neighbours which can be pricey, extending the lightwell means planning permission is probably required - plus building regs will be required for the actual creation of the basement space, ie ventilation, fire escape routes etc. Like I say, big job that needs a lot of thought.

Double Edit! Does the price include for any kind of structural engineer? You'll need calcs from them to give to building control for a job like this.

Ultra Edit! Interesting link here. London biased, so not all of it may not be applicable, but theres some interesting bits about what you need to consider beyond just the basic building work. As I keep harping on - Big job! http://property.timesonline.co.uk/tol/life_and_style/property/interiors/article2875418.ece

No drainage or services under the floors - already checked

Digging down between 0.5 to 3 feet depending (bear in mind the floor is uneven atm)

Structural engineer has already done plans, and is being carried out under building control

Will probably need party wall

---

edit

---

The Times article there is more pertaining to retrofit basements - my house already has a basement, I just want to add some exrta headroom plus the extra dig associated with the hardcore/ insulateion/ screed floor

bosseyed

Good stuff

Pretty sure you'll need party wall.

And to actually try and give an opinion on the questions in your original post - yeah, to me the last couple of items seem a bit expensive. Like you say, nearly £20k for some tanking and a bog standard block wall.....not sure thats reasonable.

And £25k to dig down that far, then pour a new slab also seems quite high too. A lot of that is just unskilled labour, cutting digging, humping rubble I'd imagine, so not sure how it can add up to that much money.

More quotes I suppose, see how prices run. Or get a detailed breakdown from whoever gave you the original quote and see if it sounds reasonable.

Good luck

littlesnuggy

When you say 'tanking' what do you actually mean? Tanking refers to a specific type of waterproofing where a cementitious coating is applied to the internal walls - it's no longer the best option, and often works out more expensive than the now preferred method of using cavity drain membranes. You do say 'tanking membrane', so perhaps this is actually what you've been quoted for. Also, I hope you've gone to a specialist waterproofing firm for this and not just the builder.

jc808

littlesnuggy wrote: »

When you say 'tanking' what do you actually mean? Tanking refers to a specific type of waterproofing where a cementitious coating is applied to the internal walls - it's no longer the best option, and often works out more expensive than the now preferred method of using cavity drain membranes. You do say 'tanking membrane', so perhaps this is actually what you've been quoted for. Also, I hope you've gone to a specialist waterproofing firm for this and not just the builder.

should have clarified - tanking here is used generically

specific method by the struct. engineer is:

hydroform cf20 applied to walls then bloc k wall built up against it with wall ties tying it into existing solid wall

jc808

bump.........

jc808

bump?????????

phill99

The reason works to basements s so expensive is because it is so labour intensive. Every shovel full of debris has to come up the stairs and through the house to be disposed of. Then every single brick has to come through the house and down the stairs.

I suggest you get some more quotes.