Building near retaining wall

[qwertybob]

Hi all,

I'm looking at the feasibility of building a single-storey side extension (marked in red on the sketch) on a property I don't yet own. It would be built well within 3m from neighbours garage and a retaining wall.

I believe the depth of foundations is likely to be an issue, and the presence of the retaining wall is leaving me a little confused.

Which of the following approaches would be correct?

Consider base of retaining wall foundations as foundation depth as side foundation of garage on upper side of wall would be supported by the wall and in turn its foundations.

Consider base of garage foundations as foundations depth.

thanks for reading.

Untitled

• qwertybob
• 28 Dec 2014
• 1

 

[Alastairreid]

What does the engineers drawings say ?

 

[noseall]

You may have to dig the adjacent wall foundation in stages rather in one hit.

Engineers, building control, architects etc, love to put the onus onto the builder regards these little gems. I like to respond with the 'duty of care' statement.

 

[theprinceofdarkness]

I once built a garage in the situation of your neighbours garage. Using a 9" fence borer, I dug holes at 4' centres down to a stable level of soil, about 5' on the step side and 2' on the side adjacent to the house. each hole then had 4 vertical rebars in which were bent over to join the rebars that sat in the ring beam (about 18" wide and 6" thick) and innto the over site 4" concrete which also had mesh laid in it. It seemed OK after 25 years.
So in your case I would put in the hole every 3' and 3' deep with a beam across the top of them with the rebars in, on the retaining wall side. Leaving the soil in between the holes should keep everything in place during the construction time.
Frank