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I need to understand groundworks

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So having had our offer accepted on a building plot with full PP, I have been researching like mad the whole groundworks stage and my head is spinning with questions.

1)  Installation of septic tank and drainage field

2) Trench or Strip footings.  How do you run  the soil pipes through the concrete if you go trench fill.  I understand that for strip you just use concrete lintels.

3) Installation of soak away

4) Beam and block OR just install the concrete slab with UHF straight away and be done with the the concrete / insulation / uhf / concrete layer approach  

5) How will the soil pipes run to the septic tank and does the approach differ depending upon whether you go beam and block or solid slab floor.  I have seen that with beam and block, the pipes simply run in the void under the beam and block floor.

5) What order are these things done.


Does anyone know of a good resource for this stuff.  I have the Housebuilder's Bible, but this does not really cover this stuff in much detail. 

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Sounds like you have the basics approved i.e. house will look like this and X number of bedrooms etc.


You now need the detailed drawings, in Scotland that would be move to the building warrant stage, think it's the building regs stage in England. In Scotland you would also have a full structural design package. That would detail much of what you are asking.


Soak aways need to be designed and are based around a percolation test of the soil.


Never seen why people build a house with a cold air stream blowing below the house, but many think block and beam is great.


36 minutes ago, flanagaj said:

What order are these things done.

1. Engage an architect or architectural designer to get the details sorted and approved.


Then you start at the bottom and build up. Foundation design will depend on the site and conditions it could also vary depending on house construction type.

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90% of the answers for all the questions will change depending on your ground conditions, your finished floor level,FFL,

and your design choice for the floor and house. 

you need to understand the differences between different floor construction and which one you prefer before you ask the questions on how to install a certain one. 

you mentioned block n beam, this would have been my last choice, but I was pushed in this direction by the ground conditions. 

have you been to the self build centre in Swindon, this place has every different build method on show and is a wealth of knowledge, 


I think I would slow down a little and get your plot purchase sorted and go and sit there and get a feel for what you would like to build and the quality you want to achieve, then get some ground investigation done, come back and ask about that, then do some research on different methods. 

it’s pointless getting your head around strip footings if your ground investigation says you need piled foundation. 
and it’s pointless designing an insulated slab if your flood risk says the house has to be raised up 1.2m 

so I think your a little bit early with worries about foundation type without knowing some of the site constraints. 

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55 minutes ago, flanagaj said:

good resource for this

It's all in BH already.

If it seems boggling, it is.

Research a thing at a time.

Beam and block is a problem solver,  and I'm not against it.


What you're asking is all ultrasensible. 

1,2, 3,5 leave til later. 

In simplistic terms:

4 is what to look into first. Slab if it's good ground, and level

B and b  perhaps, if it's poor ground or has to be elevated, or on a big slope OR if you can't get lorries near.


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One other point I forgot to mention surrounds the finished floor level.  The PP obviously has proposed elevations, but when it comes to the finished floor level, is this something that is open to you to decide, or will the architect provide that information once a topographic survey has been carried out?

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