structural help-rafters, joists


  #1  
Old 03-11-03, 01:14 PM
amateurhandyman
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Question structural help-rafters, joists

I recently purchased a home built in the early to mid 1920's. It is a 2 story with a gabled "barn style" roof. I had an engineer do an inspection prior to purchase and he discovered that the joists in the second floor ceiling (effectively the "floor" of the attic) run perpendicular to the rafters. He said the joists should be parallel to the rafters to prevent the roof from wanting to move outward under load (ie-snow). He recommended connecting a 2x6 near the bottom of each rafter pair, effectively making a triangle which would stiffen the roof and prevent movement. It doesn't appear that there have been any problems to date. Is this a major concern? Will his fix work? I don't want to have to worry about the roof, or my re-sale value.
 
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Old 03-11-03, 03:08 PM
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Your inspector was correct. If you have a barn style roof, it is a gambrel roof and what you have is very common for the style that was done when your home was built. You cannot build that style anymore. I guess it is up to you if you want to do as he says. Good Luck
 
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Old 03-15-03, 06:17 PM
desic
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structural help rafters

Handyman, It sounds like you have a Gambrel roof framed Perpendicular to the floor framing. There must be a wall framed
across the width of the structure at first floor which is a bearing wall for the second floor joists. A gambrel roof with its typically steep pitch is not so much a concern with regard to snow load as it is to Wind load.Important considerations are the connection of the second floor sheathing to the perimeter and the location of
interior partitions and their capacity to resist wind shear. The
collar ties utilized at the junction of the two roof slopes cannot be
messed with unless the consideration of knuckle braces is addressed. I believe you posted another question with regards to
a doubled joist in the first floor framing along with a beam and
column line running in opposite directions. correct? It is a good
practice of conscientious builders and designers to double up or
more under a parallel partition to support the additional dead
load of that wall in addition to the required live load.This member
could be picking up a concentrated load from a point above. The
way you are picking apart the BONES of this structure sounds like
you would like to remove some walls.you are to be commended
for your investigative efforts.However it is strongly recommended
to consult with a design professional (at the site) to establish the
perameters for your proposed renovations.Remember ... Plan your
work and work your plan.
 
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Old 03-15-03, 08:27 PM
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desic,

I'll second that! I had to do modifications to one last year. There were walls on main supporting the ceiling joists (attic) and nothing holding the side walls in properly. Flexing was the issue. Took some work but we got it done. On site review is necessary to establish how to restore the structural integrity.

Good Luck!
 
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Old 03-15-03, 09:40 PM
amateurhandyman
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I thought I posted a reply but now I don't see it so my apologies if this turns up twice. I definitely plan to get professional help (for a variety of things, including this wall ). My intention is to remove the wall between the kitchen and what is now the dining room. I'm trying to get an idea of how big the job will be. Obviously it will be easier if the wall is just a partition as opposed to "load bearing". If I understood your post correctly, the doubled joist under this wall could just be to support the weight of the wall and doesn't mean that the wall is necessarily integrakl to the structure?
 
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Old 03-15-03, 09:45 PM
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PS- (I included this in that previous poet that I now can't find but...) there are two parallel walls on the main (first) floor that run the width of the house and appear to carry the load from the ceiling joist above. These two walls basically enclose the stairwell and adjacent hallway.
 
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Old 03-16-03, 08:16 AM
desic
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scope of work removing brg.ptn.

Amatyman, Yes you understood my post correctly. A quick description of the "job size". It is important to confirm if it is a load
bearing wall. Locate your basement beam line and try to follow it
up to the closest wall. (they may occasionally be offset) Follow this wall up to second floor to determine if it is supporting those joists. Follow me? Let's supose the wall is bearing. You will need to frame atleast two walls. One on each side of the wall you want
to remove. These will run the full length and be close enough to the bearing while still allowing room to work. Critical is checking the 1st. Fl. joists. Their condition ie...are they notched,cracked,is
there any signs of wood borer damage. What is their connection
to the beam? over framed,flush framed,notched,It is by this review you will determine if walls need to be introduced in the basement. If you opt not to frame temporary walls in the basmt.
When you remove the subject wall above you will want to get the
new beam that will be required in place and restrained sooner so
the temp. walls do not create a shear problem on the connection
below. Prior to removing subject wall address all possible inclusions such as electrical,plumbing and what not. I recommend
removal of the wall in layers rather than turning a reciprocating saw loose on it (exploratory surgery) A very important aspect of
the new beam installation is to post down solid through the 1st.
floor cavity to the beam below and the introduction of a new column and adequate footing for this column.Sometimes I have
utilized an existing column to determine how big the opening above would be, It's a by chance thing but something to look for.
Worst case scenario is the new column would end up through a
hot water heater or the furnace or other undesireable place. It can still be accomplished by flitching the existing beam to take the
concentrated load from the beam above. This is for a structural
engineer to determine. When everything has been properly fastened and restrained (the connection of the 2nd Fl. joists to the new beam is important to prevent rotation of the beam) Again
we don't know spans or depth of members but this is your hypothetical project. Once everything is "buttoned" up you can
remove your temporary partitions,stand back and take in the view. Ya right ... now you have finish work and clean up and.. and.
Depending on the conditions it is sometimes desireable to jack up
the floors slightly and carefully prior to erecting the temp. walls.
This approach would require walls up and down. Knowing the
architectural style of the home is a consideration given to your
project also. Maybe you create a large opening leaving half walls
on the ends and introduce decorative columns,you follow me?
Listen to the building it will talk to you! Well handyman I hope this
has helped you in sizing up this portion of the work and given you
food for thought as to the approach. Work smart and hard.
 
 

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