Adding the foundation for a porch (Ed)

[Nathan110]

Hello all

Dug foundation for porch

Bit confused

The water pipe is obvious as is the electric

Is the top large conduit the new gas and the other (below it) old gas? Can anyone confirm who is familiar with this

Am I correct that only the gas needs sleeving? Is it sufficient with some gutter downpipe. Please advise

Thanks

 

[Diver Fred]

Is that the recommended / approved depth? looks rather shallow to me.

Is the metal pipe going the full width (galvanised) steel? If it is then it ought to be cleaned up with a wire brush and at least 2 heavy coats of bitumen paint applying.I
The flexible cable I'd be looking at wrapping with some 50mm loft insulation and a some gutter downpipes put around that and if you can get it into the undisturbed ground at the sides of the hole.
Everything (pipes & cables) needs wrapping with 50mm loft insulation and that wrapped with polythene sheeting to allow for movement.

Of course your local Building Control may have differing ideas.

 

[Nathan110]

Yes 55cm need to finish a bit more digging to get it to 60. Anyway,it's a small 3sqm porch.


Sorry not sure on your answer but are you saying electric and water need to be sleeved/protected too ? I appreciate the gas has to be

 

[Diver Fred]

Sorry not sure on your answer but are you saying electric and water need to be sleeved/protected too ? I appreciate the gas has to be

Yes, every pipe, duct needs to be protected from movement of new foundations during settlement.

 

[noseall]

Yes 55cm need to finish a bit more digging to get it to 60.

How did you arrive at 60 (cm) ?
A standard dig would locate the existing foundation bottom and then either match or go deeper.

 

[Nathan110]

For a little 3sqm upvc porch ? You ok ?

 

[noseall]

For a little 3sqm upvc porch ? You ok ?

I'm fine thanks.

 

[Notch7]

For a little 3sqm upvc porch ? You ok ?

A professional builder would most likely match house foundation depth.

In reality it’s impossible to state a depth as a set figure, it is entirely dependent on the ground you have. The only purpose of foundation depth is to reach stable, load bearing soil.

The bottom of your trench needs to be hard sub soil with no shrinkable clay or top soil.

A porch with a low dwarf wall and the rest of the structure in timber or upvc will be quite tolerant to a bit movement, if it’s walls upto plate height, not so much

 

[ajohn]

A porch with a low dwarf wall and the rest of the structure in timber or upvc will be quite tolerant to a bit movement, if it’s walls upto plate height, not so much

Wouldn't a porch be more like a conservatory? More of a concrete slab than true foundations.

 

[mitch66]

Wouldn't a porch be more like a conservatory? More of a concrete slab than true foundations.

Fair question but It'll depend on the obvious. Weight of the structure and the ground. Get someone that knows to have a look. Don't wanna do it twice.

 

[noseall]

Wouldn't a porch be more like a conservatory? More of a concrete slab than true foundations.

Not especially no. If you mean are they both exempt from B' Regulations, then largely they are yes.

 

[^woody^]

Weight of the structure and the ground

That's a common misconception " I don't need deep foundations because the building is only small/light"

The idea of foundations is to transfer the load, however small, down to a stable layer in the ground, so that ground movement particularly seasonal movement does not cause the building above to move.