Potential single-storey self build in SE

[Thorfun]

15 minutes ago, Katie AG said:

isn’t ridge height measured from ground floor level?

nope. afaik, ridge height is from ground level. so the height of the ridge above ground level.

[PeterW]

2 hours ago, Katie AG said:

isn’t ridge height measured from ground floor level? So even if we dug down a bit the ridge height would still be set? I imagine there may be wiggle room with planners though if this was explained. 

nope it is measured from the surrounding existing ground level.

 

2 hours ago, Katie AG said:

I imagine though having a semi basement adds on quite a bit of cost??

not really - I’m not talking a fully tanked sort of thing, just dropping the rear down into the ground by 1m (which is 5 steps) and build a retaining wall either side then you’ve got very little issue unless you have very high water table or  have very shallow drain runs (but this can be designed out) and a short patio / terrace gives you enough for lots more headroom.

 

[Phil Sacre]

VAT. The builder claims VAT back quarterly.

I know a self builder who created a limited company, registered for VAT, claimed the VAT back quarterly. Shut the company.

[Phil Sacre]

I would think that excavating a metre, so that the ground floor was 1m lower with the ridge where it was always already going to be,

 

is going to add costs for excavator, operator, muckaway lorries, more concrete (most of it waterproof), reinforcing steel, timber for formwork a lot of which could end up in your house, labour and concrete pumps. You will save something on footings.

Are you in chalk?

Will you find chalk 1m down?

Chalk drains. Very advantageous for a basement structure.

 

I did exactly this to be able to build a studio at the end of the garden without building any higher than the neighbour's shed.

 

If 140 sq m like your neighbour:

13T excavator would dig this in a day but would need to hang around for 10 lorries to fill. Perhaps 3 days. About £900 with delivery and collection. (VAT zero rated if digger comes with its own operator) £450.

140 cubic metres of soil is about 10 trucks. About £3000.

      Or you could pay less for a smaller digger and pay more for grab lorries.

Up to 60 cu m of waterproof concrete £12,000.

Steel. Max 2 tonnes. Max £1000 with delivery.

Timber about £3000. Less if you will have to buy some but you re-use this instead.

Labour. I don't pay myself so I don't know. Perhaps £15,000?

2 pumps £1000.

That totals about £36,000

plus you will have more cost fitting out the extra rooms in the roof - but that is the gain. Extra rooms, added house value.

 

Less some of the cost of footings.

 

 

 

 

[PeterW]

1 hour ago, Phil Sacre said:

VAT. The builder claims VAT back quarterly.

I know a self builder who created a limited company, registered for VAT, claimed the VAT back quarterly. Shut the company.

And the VAT man cometh ..!! They have got wise to that and there are horrendous tax implications 

[Bournbrook]

2 hours ago, Phil Sacre said:

I would think that excavating a metre, so that the ground floor was 1m lower with the ridge where it was always already going to be,

 

is going to add costs for excavator, operator, muckaway lorries, more concrete (most of it waterproof), reinforcing steel, timber for formwork a lot of which could end up in your house, labour and concrete pumps. You will save something on footings.

Are you in chalk?

Will you find chalk 1m down?

Chalk drains. Very advantageous for a basement structure.

 

I did exactly this to be able to build a studio at the end of the garden without building any higher than the neighbour's shed.

 

If 140 sq m like your neighbour:

13T excavator would dig this in a day but would need to hang around for 10 lorries to fill. Perhaps 3 days. About £900 with delivery and collection. (VAT zero rated if digger comes with its own operator) £450.

140 cubic metres of soil is about 10 trucks. About £3000.

      Or you could pay less for a smaller digger and pay more for grab lorries.

Up to 60 cu m of waterproof concrete £12,000.

Steel. Max 2 tonnes. Max £1000 with delivery.

Timber about £3000. Less if you will have to buy some but you re-use this instead.

Labour. I don't pay myself so I don't know. Perhaps £15,000?

2 pumps £1000.

That totals about £36,000

plus you will have more cost fitting out the extra rooms in the roof - but that is the gain. Extra rooms, added house value.

 

Less some of the cost of footings.

 

 

 

 

This level of detail is incredibly helpful - thanks so much. 
 

actually we would need a fair bit of excavation anyway as our garden seems a bit higher than the next door neighbours, so good to have an idea of costs. 
 

As is probably the case with a lot of people, whether we could afford to do something like this all depend on how much cash we can release from our current house! Definitely makes sense to maximise value, but all a balancing act. 
 

really appreciate you taking the time to write this all out!

[Jilly]

19 hours ago, Katie AG said:

Yes definitely. Very worried about this so have posted on the finance thread to see if anyone has any advice on better finance methods!

Live on site in a mobile home is the answer most people come up with!

[SteamyTea]

On 15/04/2023 at 10:46, Katie AG said:

what’s the best single piece of advice you have

Welcome.

 

Design the roof to give you the best PV production in winter.

Then lots of insulation and airtightness tapes.