Building an extension need advice on Groundwork?

T

The Rock

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I have 3 weeks to go for planning to come through for an extension to the side of my house , this basically is going to be a living room, it is 7.2m x 5.1m. I am going direct labour on this, but i am having a problem getting someone to do the ground work ie. up to floor level, so it appears i might have to tackle this myself.

Is there any sites out there that can give advice on this, what i want to know is foundation widths and depths, footings, insulation, pouring floors everything basically involved with getting up to floor level.
 
Re: Building an extension need advice on Groundwork??

The Rock said:
I have 3 weeks to go for planning to come through for an extension to the side of my house , this basically is going to be a living room, it is 7.2m x 5.1m. I am going direct labour on this, but i am having a problem getting someone to do the ground work ie. up to floor level, so it appears i might have to tackle this myself.

Is there any sites out there that can give advice on this, what i want to know is foundation widths and depths, footings, insulation, pouring floors everything basically involved with getting up to floor level.
Click to expand...

ensure you get the homebond book proir to starting.
 
Re: Building an extension need advice on Groundwork??

Rock,

The dig you will need a mini digger and get a roll on off skip so you can get rid of it all straight away. You can get mini dumpers that fit down your side aswell so you can empty straight into the skip. The mini diggers are easy to use just take your time when you start and youll get the hang of it.

Best practice is to go down to the same level as the esisting house. When you espose the existing house foundation then this will be the top of your foundation. The widtg depends on your wall but your foundation should be three times the width of the wall.

You should get a blocklayer to put in the footings and DPC up to ground floor level. You will then need to fill the floor inside with fill up to 50mm below undersid of existing floor level. This stone must be compacted with a wacker plate.

Then you put down your insulation and cover with a DPM. you should also put insulation strips vertically up the side of the floor alongside the blockwork the same depth as the floor. The concrete goes next. Job Done.

everything is detailed in the Homebond book but I would advise having a look at a neighbour if they are doing one. There is always someone getting it done.
 
Re: Building an extension need advice on Groundwork??

The Rock said:
Is there any sites out there that can give advice on this.
Click to expand...

Buy this book.
Homebond House Building Manual
ISBN 0-9523614-3-4
Published by National House Building Guarantee.

I bought a copy from Eason many years ago. Well worth it.
 
Re: Building an extension need advice on Groundwork??

bacchus said:
Buy this book.
Homebond House Building Manual
ISBN 0-9523614-3-4
Published by National House Building Guarantee.

I bought a copy from Eason many years ago. Well worth it.
Click to expand...

Make sure you get the most current copy
 
Re: Building an extension need advice on Groundwork??

Thanks for the replies people, I have plenty of room around the house so digger access will not be a problem, as there is a lot of good 2 inch filling underneath the existing drive where the extension is going i think this can be used as back fill, also there is tarmac laid on this filling so i have a good base already to work off. I intend to cut the existing tarmac with a con saw and dig just what is required, as far as i can remember from when the house was built ( 9 yrs ago) there are 3 blocks in the footings. therfore 3 blocks deep plus the depth of foundation

Do i need to put steel into the foundations for the footings and also would i need steel mesh for the floor

Also excuse my ignorance but what is DPM.
 
Mesh is all you need in the foundation get A393 mesh if you can

DPM=Damp Proof Membrane.

Mesh A142 in the floor but it is not vital
 
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