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Fash
 
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Default Jacking up wall/floor

I'm sure the answer's here somewhere but I can't find it. Lots of
information about Americans jacking up their houses but since these are
mostly stapled together it's not really relevant to my 1750 townhouse!
The problem is that at some point in the 50's the previous owners of my
house took out a wall in the basement and on the ground floor without
putting in proper support. The beam they used in the cellar went in
sideways (H beam instead of I beam which is about a quarter of the
stiffness.) As a result there is a significant deflection on the beam
in the cellar which translates into a bow in the floor at ground and
first floor level.
I'm having it dealt with by putting in new steels at first floor and
ground floor level. The question is what is the best way of raising the
floors back to approximately level before putting the new beams in? I
don't really want to just preserve the existing bow although some
unevenness will remain after jacking.
Is it is simple as tightening the acrows until they lift the structure
or would I (or at least my builder) be better off using a second set of
Acrows with hydraulic jacks to do the lift with the original acrows
then raised to take the load. This way I could raise it a little on the
hydraulics and then move up the screw jacks to maintain the lift.
Anyone done this before?
All advice (although especially good advice) welcomed.

Fash

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Peter Crosland
 
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Default

Sounds like the advice of a qualified structural engineer would be
advisable.

Regards from Peter Crosland


  #3   Report Post  
Lobster
 
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Default

Fash wrote:
I'm sure the answer's here somewhere but I can't find it. Lots of
information about Americans jacking up their houses but since these are
mostly stapled together it's not really relevant to my 1750 townhouse!
The problem is that at some point in the 50's the previous owners of my
house took out a wall in the basement and on the ground floor without
putting in proper support. The beam they used in the cellar went in
sideways (H beam instead of I beam which is about a quarter of the
stiffness.) As a result there is a significant deflection on the beam
in the cellar which translates into a bow in the floor at ground and
first floor level.
I'm having it dealt with by putting in new steels at first floor and
ground floor level. The question is what is the best way of raising the
floors back to approximately level before putting the new beams in? I
don't really want to just preserve the existing bow although some
unevenness will remain after jacking.
Is it is simple as tightening the acrows until they lift the structure
or would I (or at least my builder) be better off using a second set of
Acrows with hydraulic jacks to do the lift with the original acrows
then raised to take the load. This way I could raise it a little on the
hydraulics and then move up the screw jacks to maintain the lift.
Anyone done this before?
All advice (although especially good advice) welcomed.


You have absolutely *got* to take the advice of a structural engineer
over this. Have you really not already done so?

IANAE but surely there would be a real risk of totally buggering up the
house by cranking the structures up as far as their original positions.
Really not worth risking losing your house (life?) over a couple of
hundred quid's worth of fees.

David
  #4   Report Post  
Jonathan Pearson
 
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Default

Fash wrote:
SNIP
Anyone done this before?
All advice (although especially good advice) welcomed.

Fash


Steel doesn't creep, so assuming that the live load hasn't changed much (and
that the beams haven't deteriorated over time and been subject to a fire
etc), then the deflection occurred when the modification was undertaken,
hence the deflection won't get worse due to the deadload - however as the
beams were installed sideways (why???) as you rightly point out the strength
has been reduced somewhat, and may deflect due to the live load (do you get
cracking in walls etc), but nevertheless given the time its been there its
unlikely to be unsafe!

You could do nothing and live with the deflection (if the live loads are
okay), however as other have pointed out you need a structural engineer and
competent builder to undertake these works as there are lots of
considerations, such as beam design, pad stones, method of works, accrow
design and location etc.. + all the consequences of jacking and moving the
up the above walls - if you plan to change the steels, warn the wife before
the quote comes in that a family holiday might be out of the question for a
good few years!

Jon




  #5   Report Post  
fred
 
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Default

In article , Lobster
writes
Fash wrote:
I'm sure the answer's here somewhere but I can't find it. Lots of
information about Americans jacking up their houses but since these are
mostly stapled together it's not really relevant to my 1750 townhouse!
The problem is that at some point in the 50's the previous owners of my
house took out a wall in the basement and on the ground floor without
putting in proper support. The beam they used in the cellar went in
sideways (H beam instead of I beam which is about a quarter of the
stiffness.) As a result there is a significant deflection on the beam
in the cellar which translates into a bow in the floor at ground and
first floor level.
I'm having it dealt with by putting in new steels at first floor and
ground floor level. The question is what is the best way of raising the
floors back to approximately level before putting the new beams in? I
don't really want to just preserve the existing bow although some
unevenness will remain after jacking.
Is it is simple as tightening the acrows until they lift the structure
or would I (or at least my builder) be better off using a second set of
Acrows with hydraulic jacks to do the lift with the original acrows
then raised to take the load. This way I could raise it a little on the
hydraulics and then move up the screw jacks to maintain the lift.
Anyone done this before?
All advice (although especially good advice) welcomed.


You have absolutely *got* to take the advice of a structural engineer
over this. Have you really not already done so?

IANAE but surely there would be a real risk of totally buggering up the
house by cranking the structures up as far as their original positions.
Really not worth risking losing your house (life?) over a couple of
hundred quid's worth of fees.


From the sound of it, it's only the floors, doesn't sound like the mother of
all disasters in the making to me.
--
fred


  #6   Report Post  
 
Posts: n/a
Default

Fash wrote:
I'm sure the answer's here somewhere but I can't find it. Lots of
information about Americans jacking up their houses but since these are
mostly stapled together it's not really relevant to my 1750 townhouse!
The problem is that at some point in the 50's the previous owners of my
house took out a wall in the basement and on the ground floor without
putting in proper support. The beam they used in the cellar went in
sideways (H beam instead of I beam which is about a quarter of the
stiffness.) As a result there is a significant deflection on the beam
in the cellar which translates into a bow in the floor at ground and
first floor level.
I'm having it dealt with by putting in new steels at first floor and
ground floor level. The question is what is the best way of raising the
floors back to approximately level before putting the new beams in? I
don't really want to just preserve the existing bow although some
unevenness will remain after jacking.
Is it is simple as tightening the acrows until they lift the structure
or would I (or at least my builder) be better off using a second set of
Acrows with hydraulic jacks to do the lift with the original acrows
then raised to take the load. This way I could raise it a little on the
hydraulics and then move up the screw jacks to maintain the lift.
Anyone done this before?
All advice (although especially good advice) welcomed.

Fash



If the only thinkg you need to move is a suspended wood floor, it can
be jacked up on car jacks, removing loads off the floor first. It can
then all be propped while the steelwork is removed.

If OTOH you wish to move a structure that supports a wall, as others
have said I wouldnt consider it at all, not without expert advice at
the minimum.


NT

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Fash
 
Posts: n/a
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I'm not completely stupid, so YES I do have a structural engineer,
=A31600 so far and still counting. Quote for replacing/renewing steels
is ~=A313k including some other stuff I haven't described. I generally
find it helps to be informed before speaking to my structural engineer
since I last did any beam calculations at Uni ~12 years ago. That's why
I asked for anyone with experience of doing it/seeing it done to
comment.
I am also aware that any deflection took place when the inadequate
steel was put in before. The point still remains that the house dropped
when the steel was put in due to its inadequacy (the deflection on the
steel doesn't need to be measured it can be seen with the naked eye)
and I'd like some of it back.
Anyway back to the first point, of course I will speak to the
Structural engineer I just want to go in armed with suggestions, so far
it's definitely helped me to get what I want in terms of design.

Further practical advice welcomed.

Fash

wrote:
Fash wrote:
I'm sure the answer's here somewhere but I can't find it. Lots of
information about Americans jacking up their houses but since these are
mostly stapled together it's not really relevant to my 1750 townhouse!
The problem is that at some point in the 50's the previous owners of my
house took out a wall in the basement and on the ground floor without
putting in proper support. The beam they used in the cellar went in
sideways (H beam instead of I beam which is about a quarter of the
stiffness.) As a result there is a significant deflection on the beam
in the cellar which translates into a bow in the floor at ground and
first floor level.
I'm having it dealt with by putting in new steels at first floor and
ground floor level. The question is what is the best way of raising the
floors back to approximately level before putting the new beams in? I
don't really want to just preserve the existing bow although some
unevenness will remain after jacking.
Is it is simple as tightening the acrows until they lift the structure
or would I (or at least my builder) be better off using a second set of
Acrows with hydraulic jacks to do the lift with the original acrows
then raised to take the load. This way I could raise it a little on the
hydraulics and then move up the screw jacks to maintain the lift.
Anyone done this before?
All advice (although especially good advice) welcomed.

Fash



If the only thinkg you need to move is a suspended wood floor, it can
be jacked up on car jacks, removing loads off the floor first. It can
then all be propped while the steelwork is removed.

If OTOH you wish to move a structure that supports a wall, as others
have said I wouldnt consider it at all, not without expert advice at
the minimum.
=20
=20
NT


  #8   Report Post  
Owain
 
Posts: n/a
Default

Fash wrote:
Anyway back to the first point, of course I will speak to the
Structural engineer I just want to go in armed with suggestions, so far
it's definitely helped me to get what I want in terms of design.
Further practical advice welcomed.


T i m 's gotta mate selling a 4 post car lift ....

Owain

  #9   Report Post  
Mike B
 
Posts: n/a
Default


"Fash" wrote in message
ups.com...
back to the first point, of course I will speak to the
Structural engineer I just want to go in armed with suggestions, so far
it's definitely helped me to get what I want in terms of design.


Further practical advice welcomed.


One key point when jacking the middle of any beam is how far does it extend
into the walls. If the walls have been built onto (or settled onto) the
beam entering them at a certain angle then you will need to support the beam
at the ends and remake the wall supports as well.



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tony sayer
 
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Default

In article , Mike B
writes

"Fash" wrote in message
oups.com...
back to the first point, of course I will speak to the
Structural engineer I just want to go in armed with suggestions, so far
it's definitely helped me to get what I want in terms of design.


Further practical advice welcomed.


One key point when jacking the middle of any beam is how far does it extend
into the walls. If the walls have been built onto (or settled onto) the
beam entering them at a certain angle then you will need to support the beam
at the ends and remake the wall supports as well.




FWIW I remember many years ago knocking out the middle wall to make one
big room downstairs, and after winding the acrows up and new beam in and
well hammered shims into place on the new engineering brick support some
of the doors upstairs opened a whole lot easier)
--
Tony Sayer



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Andy Luckman (AJL Electronics)
 
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In article . com, Fash
wrote:

I'm not completely stupid,


Strange, by posting upside down and not trimming a single syllable, you
certainly appear so.


--
AJL Electronics (G6FGO) Ltd : Satellite and TV aerial systems
http://www.classicmicrocars.co.uk : http://www.ajlelectronics.co.uk

** Would you like to learn to post effectively? **
** http://www.allmyfaqs.com/faq.pl?How_to_post **

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The Natural Philosopher
 
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Andy Luckman (AJL Electronics) wrote:

In article . com, Fash
wrote:


I'm not completely stupid,



Strange, by posting upside down and not trimming a single syllable, you
certainly appear so.


No, thats merely usenet inexperience and a welcome lack of pedantry and
the sort of patronising attitude that comes from those who learn to use
Usenet 10 years after everyone else, but 2 years before the current newbies.
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