Side and Rear Extension on Poor Ground
Side and Rear Extension on Poor Ground
(OP)
Hi,
I have a project which involves the side and rear extension of an existing dwelling house, 2 storey extension to the side and single storey to the rear.
See attached sketch of same. I have the following queries:
Query 1:
The existing foundations are 2m down due to poor ground. Probes carried out on the ground to the side and rear of the existing dwelling indicate that the ground is also poor likely due to backfill. Due to this and the fact that the extension is very close to the adjoining property boundary I have decided to pile and suspend the entire extension (side and rear). I have gone with a single line of 200mm CFA piles socketed into rock (circa 2-3m centres) with a series of RC cross beams and suspended RC slab. Does this seem like a reasonable solution? Any comments welcome.
Query 2:
At the rear of the existing house the Architect has taken out 3/4 of the rear wall at ground floor level to create a link between the old and the new. So I am proposing to install a steel portal to stiffen up the back of the house. My query is that I am proposing to install a single 254x254x73UC to support the 2 existing wall leafs (100 outer, 100 cavity & 100 inner leaf). This beam is heavy but the connection detail to the adjoining column will be easier than going with 2 beams (1 for each leaf). Anyone see an issue with this? Also the pile caps that support the columns of this portal have 2 piles so I am proposing to run a beam thickening in the slab perpendicular to these pile caps to stabilise the pile caps. Is this overkill?
regards,
J
I have a project which involves the side and rear extension of an existing dwelling house, 2 storey extension to the side and single storey to the rear.
See attached sketch of same. I have the following queries:
Query 1:
The existing foundations are 2m down due to poor ground. Probes carried out on the ground to the side and rear of the existing dwelling indicate that the ground is also poor likely due to backfill. Due to this and the fact that the extension is very close to the adjoining property boundary I have decided to pile and suspend the entire extension (side and rear). I have gone with a single line of 200mm CFA piles socketed into rock (circa 2-3m centres) with a series of RC cross beams and suspended RC slab. Does this seem like a reasonable solution? Any comments welcome.
Query 2:
At the rear of the existing house the Architect has taken out 3/4 of the rear wall at ground floor level to create a link between the old and the new. So I am proposing to install a steel portal to stiffen up the back of the house. My query is that I am proposing to install a single 254x254x73UC to support the 2 existing wall leafs (100 outer, 100 cavity & 100 inner leaf). This beam is heavy but the connection detail to the adjoining column will be easier than going with 2 beams (1 for each leaf). Anyone see an issue with this? Also the pile caps that support the columns of this portal have 2 piles so I am proposing to run a beam thickening in the slab perpendicular to these pile caps to stabilise the pile caps. Is this overkill?
regards,
J





