Hi there everyone,
I have been looking around the site and have been unable to find something directly related to this, although it is covered in parts on various threads.
My house has a basement, with a separate entrance from the rear garden. It equates to about four rooms in total. I wish to make use of this space and convert it into habitable rooms. I have been researching it as best as i can and brought various conversion specialists to give me opinions and quotes.
the following is agreed by all the experts who have visited the address.
1. I would need building regulation approval.
2. The cellar would need to be dug in further in places in order for the appropraite headroom to be achieved.
3. Some walls may need to be underpinned as the digging will expose foundations in certain areas.
4. a concrete base will then be laid to achieve the intial base with alleys on the side to allow any rising water to drain away and a pumped will be used to move out the water of the cellar.
5.on top of this base a membrance will be laid which will allow the water to drain out .. on top of this will be the floor.
6. the walls will also need to be lined with membrane to deal with damp etc. then battened and plasterboarded
7.after that the cosmetic finishes, plasterboards , ceilings will need to be done.
Problems.
Cost ..as the quotes i have recieved range from £20k to £40k ..
Different opinions on underpinning some said not reqired others have said in parts and one said all over !!
So far.....I was thinking to tackle the project myself and bringing in expert advice where and when needed.
1.I have arranged for a plans to be drawn and submitted for approval.
2. i will be able to sort out the excavation in order to get adequate height for the floors etc
Question...
Has anyone done anything like this .. what is the best way to go about this ...can this be done step by step ...the main problem i see is the issue of foundation underpinning ... water drainage ..DPC on floor and walls (although the cellar is fairly dry).. no doubt there will be other issues to consider all views and advice welcome.
This really isn't my area of expertise, although my civil engineering company did get involved with a number of underpinning projects before I was disabled, and it's not something I would ever recommend for DIY. There is so much that can go wrong, it's much better to leave it to the professionals.
You would need to check with your mortgage provider as the insurances and professional indemnity required of underpinning contractors is considerable and they might not be too happy at you having a go yerself!
many thx for the reply ...granted that's one area that i'll leave to the proffessionals..
re the other issue's ..is there much difference to the base that will need to laid in the cellar to the one's for garages etc ... bearing in mind this will eventuallly be used as a living area.. one of the experts said it will need to be hard mix of gravel and concrete as it allows water to drain away easily .. advice in this area welcome thx
I'd suggest consulting a structural engineer because, if there's any problem with water table levels, tyou will probably have to use a completely watertight floor with a impermeable damp proof membrane, which may need to be sprcified to suit BCO requirements.
One major diff between a garage floor and that for a living area is the need for insulation to minimise heat loss (Document L), and the planned finished surface needs some consideration. It's often easier to rely on asphalt or a self-levelling compound if you're having a carpeted floor, but if you're planning on wooden flooring, then a standard fine tamp finish to the concrete should be adequate.
As for the sub-base, this will be dictated by ground conditions and water table levels, but I'd expect a minimum of 100mm of approved granular material, blinded with grit sand, covered with the DPM. There may be a requirement for "selected free draining material" and for a network of perforated pipes if there is concern regarding groundwater.
All this reinforces the earlier point I made about bringing in the professionals for a job such as this. They deal with these issues every week and what might seem daunting to me and thee, will be a piece of <s>pi...</s> cake to them!
