The amazing transforming garage

[puntloos]

On 25/11/2019 at 08:46, Bitpipe said:

 

Agree - I have a full footprint basement including plant room. Plenty of junk (that i'm trying to get rid off) and two teenagers (they will go once the junk is sorted).

Do you have any idea how much this cost you? I would LOVE a basement (also to shield the noise of the plant room?) but not sure my love stretches to .. well full footprint? Like an entire underground floor? That seems a little overkill-y.. - but at least a garage-sized one still would be probably 50K or so?

 

Would it make the basement cheaper to be under the garage??

On 25/11/2019 at 12:23, scottishjohn said:

A friend of mine has a stand alone garage wall height 10ft 6"

he has a 4 poster ramp in there  which has all his workshop equip on it,since he got rid of second car 

put ramp up --car drives below it and you got 5ft+ of space for stuff on top of ramp --with that or another car 

s/h four poster ramp --£500- £1000

that is a cheap second garage

 

 

I toyed with the idea too.. but even with my planned 2m70 ceiling I can't really "store" the car and still have ample space below I think..

 

[Ferdinand]

5 minutes ago, puntloos said:

 

Fair point, and indeed, the 'resale value' is quite secondary for me.. of course I don't want to do something that absolutely ruins it but ..

 

 

Sale value will adjust for the value of whatever is there, but if you were *really* skimped on the "parking spaces" (say 1 instead of a required 3 rather than 2 instead of 3 because one was notionally your "garage" which has been rearranged), then that might lose some buyers.

 

On the width, I read the dimension as 2.990 but I see that was the lengthways for the Utility, and it is actually just over 3m - should be fine but check if counting parking spaces is important.

 

F

[scottishjohn]

46 minutes ago, puntloos said:

Cars getting bigger.. mm.. I see two trends

the reason cars have been getting largerover the years is encaqp testing --cars have to be bigger + heavier for all the safety measures 

internal crash bars ,air bags etc  all take space so if to get same intewrnal space car gets bigger

[Bitpipe]

1 hour ago, puntloos said:

Do you have any idea how much this cost you? I would LOVE a basement (also to shield the noise of the plant room?) but not sure my love stretches to .. well full footprint? Like an entire underground floor? That seems a little overkill-y.. - but at least a garage-sized one still would be probably 50K or so?

 

Would it make the basement cheaper to be under the garage??

 

To the penny

 

£120k (2015) for a 110 m2 basement including demolition of old house and services in ground.

Saves on foundation costs too.

 

Yes - it’s an entire underground floor, fully finished, just like any other room in house with big light wells so bright in daytime.

 

Per m2 cheapest rooms in house.
 

Smaller is usually more expensive per m2 due to mobilisation costs.

[JFDIY]

Insulate the whole space, have the step down at the doorway and consider if you could make the wall on rails so you can re-position it anywhere in the length of garage, depending on your or future owners needs.

 

 

[puntloos]

11 hours ago, Bitpipe said:

To the penny

 

£120k (2015) for a 110 m2 basement including demolition of old house and services in ground.

Saves on foundation costs too.

Can you elaborate on this one?

 

 

 

11 hours ago, Bitpipe said:

 

Yes - it’s an entire underground floor, fully finished, just like any other room in house with big light wells so bright in daytime.

 

Why so much? Space constrained? I might fire off a separate thread if this becomes interesting but I've been wondering about what the 'optimal' ratios for a plot is..  if you have 500sqm plot in a town, would you want 50% garden, 50% house footprint? How many floors? Is bigger always better for resale value, if you can get away with it with the planning teams?

 

In our house we have heavily prioritized the main spaces (hall, living, kitchen) and sacrificed the size/location of other rooms. Not terrible but eg the average bedroom is say 3.5x4m. 

 

11 hours ago, Bitpipe said:

 

Per m2 cheapest rooms in house.

 

This is the surprising one.. normally the rule of thumb I'm aware of is (say) 2000/sqm for 'normal space' and like 3000 for basement.. Why is yours the reverse? In our situation we have a smallish plot where "all things being equal" I'd love to have some rooms in the ground rather than competing for garden space.. I'd even be willing to pay a premium but 50% more is steep... 

 

11 hours ago, Bitpipe said:

Smaller is usually more expensive per m2 due to mobilisation costs.

In my context, I would only be tempted to put garage+utility+plant underground, which currently is about 4.5x7m, so 30-odd sqm.. say 45sqm so I have one extra actual room..

 

How much would a 45m2 basement, mostly under the garage cost? If exactly in proportion with your prices it would be 45/110*120 = 48,000 GBP.. But how much 'mobilisation cost' would you add to that? And given that we've been working with 2250/sqm, because apparently we're being stiffed, maybe *2..

[Bitpipe]

48 minutes ago, puntloos said:

Can you elaborate on this one?

 

Yes - normal house needs a foundation - strip or slab. Basement is a big concrete box in the ground so where it meets the house, no further foundations required.

 

In our case, we'd budgeted £50k for foundations (maybe would have been less) but given we had 2-3m of clay on gravel on chalk, traditional strip would have needed to go down quite a bit.

 

With the full footprint basement we have a passive basement slab, externally insulated basement walls meeting the passive house on top.

 

We decided not to go for a concrete lid but opted for a suspended timber floor instead, that's where the house UFH is located (no heating needed in basement, always consistent temp).

 

48 minutes ago, puntloos said:

Why so much? Space constrained? I might fire off a separate thread if this becomes interesting but I've been wondering about what the 'optimal' ratios for a plot is..  if you have 500sqm plot in a town, would you want 50% garden, 50% house footprint? How many floors? Is bigger always better for resale value, if you can get away with it with the planning teams?

 

We live in SE so floor space is at a premium, site is big (1/2 acre) but planning would not let us expand the footprint of the proposed house (110m2 ish).

 

Planning did not blink at the basement which means we've extended our habitable floor space by 50%. They're currently used as two teenager dens / rooms (xbox, tvs guitars etc) and one is almost a gym (well, has a running & rowing machine, in it plus a punch bag, and lots of boxes). Last room is full of books and will be a craft  / reading room. Plus plant room in there too with all the power distribution, gas boiler, UVC tank, MVHR etc...

 

Means rest of house is relatively un-cluttered. 

 

We still have loads of garden - too much tbh. But we also have a 3.5 storey house with just under 400m2 of habitable space.

 

48 minutes ago, puntloos said:

This is the surprising one.. normally the rule of thumb I'm aware of is (say) 2000/sqm for 'normal space' and like 3000 for basement.. Why is yours the reverse? In our situation we have a smallish plot where "all things being equal" I'd love to have some rooms in the ground rather than competing for garden space.. I'd even be willing to pay a premium but 50% more is steep... 

 

Maybe if you're digging out under an existing building but, ground conditions and site access depending, it's not expensive to dig a big hole and put a waterproof concrete box in it. Biggest single expense was muck away. Once built, the additional fit out was not expensive - obv extra electrics, plasterboard, flooring, carpentry (framing, doors, stairs & skirting) plus decoration - but as it was a big house, they were probably an extra 20-30% on what we were spending on those items anyway.

 

It has no heating or wet services and we were able to use just waterproof concrete as low ground water.

 

Basements do get cheaper per m2 as they get bigger as there is a plant mobilisation cost.

48 minutes ago, puntloos said:

How much would a 45m2 basement, mostly under the garage cost? If exactly in proportion with your prices it would be 45/110*120 = 48,000 GBP.. But how much 'mobilisation cost' would you add to that? And given that we've been working with 2250/sqm, because apparently we're being stiffed, maybe *2..

 

No idea - very dependent on your site conditions (which you only know after committing to a ground investigation), access (do you need sheet pile to secure the excavation) waterproofing (are you under the water table) etc.

 

Remember our £120k included demolition & disposal of existing plus all groundworks related to services, drainage etc so was probably closer to £100k for the basic basement itself and then we would have spent somewhere between a third to half of that on a raft or traditional foundations  - plus it adds significant value to the house and the surrounding area supports that value.

 

Go ask a local groundworker for a quote. That's what I did - if you approach anyone with 'basement' in their company name then expect to pay double - we got a quote from Glatthar (German company, make pre-fabbed watertight insulated basements) and they wanted £60k for a 35m2 basement (2013 price), £70k for 62m2 and £90k for 123m2.

 

However. this did not include any excavation or muck away etc - they needed a fully prepped hole to start work. Local friends used them, very satisfied but they were in much more challenging ground conditions (very close to Thames, very high water table.) 

Edited November 27, 2019 by Bitpipe

[puntloos]

30 minutes ago, Bitpipe said:

 

Yes - normal house needs a foundation - strip or slab. Basement is a big concrete box in the ground so where it meets the house, no further foundations required.

 

In our case, we'd budgeted £50k for foundations (maybe would have been less) but given we had 2-3m of clay on gravel on chalk, traditional strip would have needed to go down quite a bit.

 

With the full footprint basement we have a passive basement slab, externally insulated basement walls meeting the passive house on top.

 

We decided not to go for a concrete lid but opted for a suspended timber floor instead, that's where the house UFH is located (no heating needed in basement, always consistent temp).

 

So in this case, you'd either want to go "All In" with the basement as the slab, or 'not at all' perhaps, since just doing a small (35m2) basement would still need a slab anyway for passivehaus reasons?

 

What do traditional foundations cost? E.g. the bare minimum on normal clay? The info I have (but should do an inspection) is that we have chalk deep down, but "reddish brown flinty clay" of up to 40feet, covered by 1ft of silt. 

 

30 minutes ago, Bitpipe said:

 

We live in SE so floor space is at a premium, site is big (1/2 acre) but planning would not let us expand the footprint of the proposed house (110m2 ish).

 

Ah that's what I have to work with as well. ("ish" - a bit more perhaps if I leave a tiny bit of access, try for internal scaffolding etc etc.

 

30 minutes ago, Bitpipe said:

Planning did not blink at the basement which means we've extended our habitable floor space by 50%. They're currently used as two teenager dens / rooms (xbox, tvs guitars etc) and one is almost a gym (well, has a running & rowing machine, in it plus a punch bag, and lots of boxes). Last room is full of books and will be a craft  / reading room. Plus plant room in there too with all the power distribution, gas boiler, UVC tank, MVHR etc...

 

Means rest of house is relatively un-cluttered. 

 

We still have loads of garden - too much tbh. But we also have a 3.5 storey house with just under 400m2 of habitable space.

 

It's strange, you live in SE - I'm just outside the M25 on the North side myself, which is clearly a 'premium' area, but if I could count on similar (even up to 1500) I would be tempted to consider the basement..  but I'm expecting 2250/sqm optimistically total build cost (but that's including all services, e.g. QS perhaps, arch, surveyors, heating guys etc etc)

 

Did you manage to come in under 2000 total build cost in your neck of the SE-woods?

 

30 minutes ago, Bitpipe said:

 

Maybe if you're digging out under an existing building but, ground conditions and site access depending, it's not expensive to dig a big hole and put a waterproof concrete box in it.

That's what I thought! We intend to remove the existing entirely.

30 minutes ago, Bitpipe said:

Biggest single expense was muck away. Once built, the additional fit out was not expensive - obv extra electrics, plasterboard, flooring, carpentry (framing, doors, stairs & skirting) plus decoration - but as it was a big house, they were probably an extra 20-30% on what we were spending on those items anyway.

 

It has no heating or wet services and we were able to use just waterproof concrete as low ground water.

 

I'd need to find out the water sitation,  my dad ran into big trouble after a few years with this, it wasn't necessarily a high water level I think, but during heavy rains...

 

30 minutes ago, Bitpipe said:

Basements do get cheaper per m2 as they get bigger as there is a plant mobilisation cost.

 

No idea - very dependent on your site conditions (which you only know after committing to a ground investigation), access (do you need sheet pile to secure the excavation) waterproofing (are you under the water table) etc.

 

I found one document in my rough area saying that the highest this inspection found the water table was 2.0m bgl ('below ground level' I'm guessing)

 

30 minutes ago, Bitpipe said:

 

Remember our £120k included demolition & disposal of existing plus all groundworks related to services, drainage etc so was probably closer to £100k for the basic basement itself and then we would have spent somewhere between a third to half of that on a raft or traditional foundations  - plus it adds significant value to the house and the surrounding area supports that value.

 

Go ask a local groundworker for a quote. That's what I did - if you approach anyone with 'basement' in their company name then expect to pay double - we got a quote from Glatthar (German company, make pre-fabbed watertight insulated basements) and they wanted £60k for a 35m2 basement (2013 price), £70k for 62m2 and £90k for 123m2.

 

60K is pretty hefty indeed.

 

30 minutes ago, Bitpipe said:

However. this did not include any excavation or muck away etc - they needed a fully prepped hole to start work. Local friends used them, very satisfied but they were in much more challenging ground conditions (very close to Thames, very high water table.) 

Right, so in your case the local guy did it for less?

[Bitpipe]

4 hours ago, puntloos said:

 

So in this case, you'd either want to go "All In" with the basement as the slab, or 'not at all' perhaps, since just doing a small (35m2) basement would still need a slab anyway for passivehaus reasons?

 

Depends, you could still extend normal foundations / slab where there was no basement - would need to think through the insulation detail.

 

4 hours ago, puntloos said:

What do traditional foundations cost? E.g. the bare minimum on normal clay? The info I have (but should do an inspection) is that we have chalk deep down, but "reddish brown flinty clay" of up to 40feet, covered by 1ft of silt. 

 

No idea - ask a groundworker / SE.

 

4 hours ago, puntloos said:

 

Ah that's what I have to work with as well. ("ish" - a bit more perhaps if I leave a tiny bit of access, try for internal scaffolding etc etc.

 

 

It's strange, you live in SE - I'm just outside the M25 on the North side myself, which is clearly a 'premium' area, but if I could count on similar (even up to 1500) I would be tempted to consider the basement..  but I'm expecting 2250/sqm optimistically total build cost (but that's including all services, e.g. QS perhaps, arch, surveyors, heating guys etc etc)

 

Did you manage to come in under 2000 total build cost in your neck of the SE-woods?

 

Yes, total spend was about 600k so about £1500 /m2 - however this was pre Brexit when £ was 1.45 to euro and we bought a lot of the house from European suppliers  - MBC frame (priced in Euros then), Gaulhofer windows, Megabad bathrooms, Hacker kitchen, FSN doors, Sika concrete & resin etc...

 

4 hours ago, puntloos said:

That's what I thought! We intend to remove the existing entirely.

 

I'd need to find out the water sitation,  my dad ran into big trouble after a few years with this, it wasn't necessarily a high water level I think, but during heavy rains...

 

 

I found one document in my rough area saying that the highest this inspection found the water table was 2.0m bgl ('below ground level' I'm guessing)

 

 

Only way for sure is a GI with bore holes and measuring water levels over time. If you're prepared to commit a few £k then you will get a good idea whether it's cost effective or not.

 

4 hours ago, puntloos said:

60K is pretty hefty indeed.

 

Right, so in your case the local guy did it for less?

 

Yep - Glatthar would have been £90k+50k, I got it for about £100k. Ground workers are always local due to the plant mobilisation and muck away (we had 73 20t lorries). They may sub out the RC concrete formwork but that's mostly  joinery & steel work and a concrete pour every 3-4 days. Alternatively the ICF route is possible for basements but you wont see the pour quality (as it's covered in insulation c/f striking traditional formwork) so have to really trust that mix & placement is faultless.