foundations fill or trench blocks?

[goodekebab]

hi i have just got planning permission to build a single story extension on my house,i plan to do most off the work myself.
first stage of my planing is the foundations i have been told they need to be 200 deep 600 wide to be laid at a depth of 1 metre then built up to 200mm of ground level with 300 trench block or take 600mm slab up to this level.
what are the benefits of both??
the extension will be 6x4 metres on the back of the house,with a 14 foot bifold door,pitched roof with 4 veluxs
much help will be needed so please be gentle thanks

Untitled

• goodekebab
• 5 Jul 2009
• 2

 

[stuart45]

The benefit of trench fill concrete is that you don't need to pay a bricklayer to build the footings in the trench. You will need to work out your drainage in advance though.

 

[Deluks]

don't need to pay a bricklayer to build the footings in the trench

aha, but he's planning on doing it himself.
I'd lay the blocks meself rather than mix up the crete, unless you take the easier route and order in some readymix.

 

[goodekebab]

Are trench blocks easy to lay as it looks like it will cost a lot to fill the whole hole with Crete.also at what level under ground wouuld I start using the bath stone faced bricks witch are 150 high. current level of dpc is about 200 mm from floor
I plan to use a brick layer for the rest of the building
cheers

 

[noseall]

There is no comparison in my book. Fill with concrete as high as you dare. It is a lot simpler than struggling around in trenches that cave in, a nightmare to work in when wet, then all that back filling etc, etc.

As stated, just remember to allow for any drainage installations or ducting/shuttering where necessary.

Our preferred concrete height setting (where terrain allows) is 525mm below dpc. This equates to 1 course of block plus 4 courses of brick when viewed from the outer leaf or two courses of block plus one brick on the inner leaf, when building two conventional leaves of masonry.

 

[goodekebab]

Sounds the way forward cheers
does the dpc on the new build have to be at the same height as the house one ??

 

[noseall]

Sounds the way forward cheers
does the dpc on the new build have to be at the same height as the house one ??

In most cases yes. If the internal finished floor levels are to be the same.

In some instances the bco may ask you to step up the dpc a course or two higher if the external paving is rising* and is irretrievably higher than 150mm below dpc.

*In some situations where say a driveway running along the side of the house rises up to meet a garage at the rear of the dwelling.