Small Extension Self Build?

[fattony]

Been thinking more and more on this idea and have drawn up a floor plan here:

http://www.floorplanner.com/projects/20189135-new-floorplan

Couple of questions though:

1) How deep would the foundations need to be, it will be a single story less than 4m high.

2) I was planning on building the walls using 9 inch block double skin with a cavity in the middle and then having the external rendered, does that sound ok?

9 inch concrete blocks external and 9 inch celcon blocks internal?

3) The largest wall which is 6.5m could only be partially rendered as the neighbours lean to would obstruct access the render the entire wall, would that change what blocks I would need to use?

4) There will be a man hole cover under the wc I think (one of the 2 small rooms) which I would build a removable panel into the floor or is there another way?

5) Is there a way to calculate how many blocks I would need?

Thanks for the help in advance, currently the area is decked, under that is a small layer of tarmac and approx 75mm of concrete under that covering the whole area, I was intending to dig the foundations down approx 600mm or is that to shallow?

 

[studips]

it'll come under building regs dude, there are requirements and standards and visual inspections/photographic records to be met.

if you are a total novice, you might want to enlist a bit of help even at the planning stage (and a bit more credible than the guys down the pub). or get a copy of a book like the house builder bible by mark brinkley.

 

[fattony]

building regs yes but didnt think planning would be required as it doesnt extend beyond 3m past the original house and is less than 4m high.

Dont have a problem with submitting to building regs / planning as quite a few of the houses down my road have done something similar but want to get an idea of cost of materials before I decide to tackle it.

Preferred option is I dig the foundations and employ someone to build the wall, I'll do the flat roof but get someone to felt it, then internally I'll do electrics and plumbing as required but not sure how much someone would charge to do the block work, anyone care to give an estimate from the plan feel free

 

[Hugh Jaleak]

Founds depth will depend on soil type, my BCO wanted a metre depth as its in clay. Drain will need to be protected from any loading from above where it passes through the founds. Manhole, sealed access cover should be ok. Google blockwork calculator, there's a few available.

I'd give Building control a ring, mine were very helpful. They're task is to make sure work complies with regs, BCO should advise you on what he wants to see.

 

[fattony]

thanks Ill give them a call

 

[RedHerring2]

I recently had a couple of quotes for a brickie, between £11 and £13 per square meter.
Don't forget, that's per square meter for two skins, so double your square meterage of the walls.

I think there's 10 blocks to a square metre.

 

[fattony]

mmm as it'll get rendered Im tempted to have a go myself, just need to speak with BC

 

[RedHerring2]

Don't forget that, if you do employ a brickie, there'll be at least two of you on the job, therefore it'll get done in much less than half the time and winter is coming in. So fewer good days to work. When we have good days it's good to get so much more done. You'll probably find that you'll need so much more thinking time than an experienced fella.

Also, there's little tricks, like using trench blocks below ground level, that brickies are aware of.

Your BCO will probably require at least a partially filled cavity. That means building the inner skin, affixing the insulation, retained by the ties and restraints, then building the outer skin, without dropping snots down the cavity. And obviously, don't forget the ties.

These were some of the factors that I considered, anyway.