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[chrisgixer]

I'd imagine the depth of the floor strengthening, the thickness of the wall/existing foundations, and as said floor and pump need to be factored in to those drawings.


Ime you need to be EXCEPTIONALLY careful in choosing a contractor. As you suggest, conversely, this has serious repercussions if the cowboys get the job. You need someone who knows what they are doing.

My Mum had a listed building with a natural spring running thought the sellar, which was water logged up to a meter permanently for years prior to her ownership. The guy they took advice from for tanking the sellar had done numerous jobs prior to, but utterly failed on this one.

The following case went to the courts and bankrupted his company, allegedly, and took 5 years  total to complete the job with a new contractor.

Yours probably won't have a spring, but shows what can go wrong, potentially. Not to mention possible subsidence.

Shame the roof is so shallow, a nice loft extension would be safer.

That sounds awful, That is my main concern, getting the right builder but not end up spending more than the house is worth! The loft would have been great but as you say, too shallow to make good use of it

The completed job though, looks first class. Afaict anyway 

[Shackeng]

I think this is a great idea, and am amazed that in a country where building land is at a premium, we do not utilise this unused space when building new houses, as is common North America. I would think that the information required to do the job properly is now readily available, given the plethora of basement extensions underway in the capital. Good luck with the project.

[scimmy_man]

The major cost of this after digging the hole, will be underpinning the house,
a local guy built a new house with a cellar/entertainment room, it added £40k on the build costs.

[Marks DTM Calib]

Yes, it wont be cheap.

In many parts of north america they add a cellar as the footings have to be very deep anyway so as to get below the frost level seen in the winter.

[05omegav6]

Yes, it wont be cheap.

In many parts of north america they add a cellar as the footings have to be very deep anyway so as to get below the frost level seen in the winter.

Compulsory in the MidWest for tornado shelter purposes as well

[Shackeng]

I was annoyed when my house was built 37 years ago. It was on made-up ground so had to have deep footings anyway, I'm sure it would have been fairly simple to convert that area to a basement.

[pscocoa]

I have more experience of basements that I need. My daughter has a Victorian house with a cellar which has demanded a lot of attention in recent years.

What is your land height position taking into account the topography of your immediate area, underground water sources, streams etc, bottom of a hill etc etc. If you are on raised land with good drainage then move on to investigate further but still sound out your insurance company. You have to think of how much water volume/pressure you might be putting on the structure behind the retaiaing sub structure.

I have put in the Rolls Royce of basement systems which consists of:

Newton membrane tanking
Perimieter cellar floor level channel which takes water from behind membrane to a sump/float chamber
Two pumps (1 as back up note also - annual maintenenace costs) to pump water from sump up to outside drainage
Battery back up in case of mains failure

However, despite all that - and it being an old house - you have to pay very careful attnetion to the point where the membrane ceases at the top of the cellar wall and the possibility for water to trickle over.

Another issue is moisture control - strange things can happen if there is imbalance in the heat distribution - you may find cellar as the coldest/least used place manages to attract some condensation.

As with all things there will be many basement installations which are absolutely fine - but if you cut any corners and do not take advice from professionals then you may not get the desired result.

Oh yes - we also had problems with Thames Water mains burst issues and building work in area which changed the water table

[05omegav6]

The beauty of new build though, is that you can waterproof the structure from the outside rather than trying to stop water entering the room from the walls

[scimmy_man]

you would think so, but builders still manage to cock these things up.

[F1 9LFG]

I have more experience of basements that I need. My daughter has a Victorian house with a cellar which has demanded a lot of attention in recent years.

What is your land height position taking into account the topography of your immediate area, underground water sources, streams etc, bottom of a hill etc etc. If you are on raised land with good drainage then move on to investigate further but still sound out your insurance company. You have to think of how much water volume/pressure you might be putting on the structure behind the retaiaing sub structure.

I have put in the Rolls Royce of basement systems which consists of:

Newton membrane tanking
Perimieter cellar floor level channel which takes water from behind membrane to a sump/float chamber
Two pumps (1 as back up note also - annual maintenenace costs) to pump water from sump up to outside drainage
Battery back up in case of mains failure

However, despite all that - and it being an old house - you have to pay very careful attnetion to the point where the membrane ceases at the top of the cellar wall and the possibility for water to trickle over.

Another issue is moisture control - strange things can happen if there is imbalance in the heat distribution - you may find cellar as the coldest/least used place manages to attract some condensation.

As with all things there will be many basement installations which are absolutely fine - but if you cut any corners and do not take advice from professionals then you may not get the desired result.

Oh yes - we also had problems with Thames Water mains burst issues and building work in area which changed the water table

We're ''high up'' well, the surrounding areas all fall away from us. at no point does land fall towards the house, every direction from our place falls away, the ends of our street is 3-4m lower than our house.   

[F1 9LFG]

The beauty of new build though, is that you can waterproof the structure from the outside rather than trying to stop water entering the room from the walls

that would be the plan 

[F1 9LFG]

you would think so, but builders still manage to cock these things up.

Yes, I keep coming across horror stories online regarding 'new basements' and cowboys! 

[05omegav6]

you would think so, but builders still manage to cock these things up.

Yes, I keep coming across horror stories online regarding 'new basements' and cowboys! 

So lifting the sitting room floor and getting busy with a spade isn't going to work then  

[Marks DTM Calib]

you would think so, but builders still manage to cock these things up.

Yes, I keep coming across horror stories online regarding 'new basements' and cowboys! 

The key with anything is getting an understanding of what needs to be done so you have some knowledge, (thankfuly its building, its far from complex). That way you act as the quality check.

Al;so worth considering is your approach to building control as you have two options.

Full plans - where building control visit at the start of the project and the end, builders like this as they can do what they pelase as long as its not visible at the end.

Building notice - here the building inspector visits at stages of the build and signs off work as its done.

The latter is useful as it effectively is an independent quality check for you but, as you are employing a builder, its worth having the full plans drawn up (as there not required for building notice) so you can use tham as part of your contract with the builder to avoid confusion/scope creep.

[scimmy_man]

you should have the same number of inspections if B Notice as Full Plans.

private inspectors often only do 2 or 3 visits, then people ask why they are cheaper.