Replies

1. 
   Nick_Pitz | Aug 23, 1999 04:59pm | #1

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   Colm - I'm sure that as a carpenter you already realize what the problem is - I don't want to insult your intelligence. Sounds to me like you have created what is basically a timber frame on your first floor. The way timber frames deal with rack bracing is with knee braces (45 degree braces) from posts to beams. Plywood will certainly help also but maybe not as much as you might think. For plywood to be really effective as rack bracing it must be nailed along all edges and in the middle to keep it from deflecting, hence the specific nailing schedules. In what sounds like basically a timber frame, there isn't enough to nail the plywood to in order to make it really work. I have made field knee braces for some unusual framing problems and used steel tension straps or nailing plates to make sure they were doing their job. There are some good books on timber framing easily available that may give you some ideas. Knee braces can be decorative as well as functional. Hope this helps.

2. 
   Guest_ | Aug 23, 1999 06:38pm | #2

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   Colm,

   The plywood should help quite a bit if it is supported on all edges and nailed well, as Nick points out. It can ideed deflect, but only under compression forces. You might want to pull enough siding off the sides to get some plywood going both directions on every corner. If all the corners are gussetted with the plywood, then there will always be some of the plywood in tension under the load rather than compression, and you would be hard pressed to rip a well-nailed sheet of plywood.

   Might not hurt to have an engineer look at it. They are not too expensive for a quick consult.

   Steve

1. 
   Guest_ | Aug 26, 1999 03:26pm | #3

   *Steve and Nick have it right. But remember now youhave brought the entire weight of your house down on the outside walls. If the walls you removed were bering were there intermediate piers underneath. if so can your foundation take the point loads?

3. 
   aColm_Toland | Sep 02, 1999 04:11pm | #4

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   Yes Rick we put in microlams down the middle of the house and across the back wall to replace the bearing wall in the center of the house and across the back of the house where we removed the exterior wall on the first floor.
   And yes we redug the piers in the basement and put them in deeperand transferred the weight at those points directly in line so the transfer of weight is a continous member down through the house.
   I am in the process of plywooding ssome of the upper wallson the 2nd floor and some gussets in the attic.

4. 
   Guest_ | Sep 02, 1999 07:59pm | #5

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   As I picture this, it would seem that you have removed all possible shear walls from one end of the house. No amount of guess work will solve this problem. No amount of plywood applied to the upper floor or walls in the other direction will help. From the age of the house I would guess that the subfloor is solid and not plywood, so there is no diaphram action happening there. It is quite possible that this design will not work. "But now in heavy winds I have a slight wobble." A "slight wobble" in heavy winds is a precursor to catastrophic failure. Were these plans okayed by an architect or engineer? If so, ask them what to do. If not, you better get an engineer now. Didn't the building department question these changes?

1. 
   Guest_ | Sep 03, 1999 12:51am | #6

   *Re: Mike's concern,I read your description to mean that the two places lacking shear resistance now are the gable ends of the house on the first floor only (is it both ends or just one end?). Are you going to run corner-to-corner glass on these walls, or is there room at the corners for knee braces? Again, I can't recommend enough the services of an engineer.Steve

5. 
   PE_fred_matthews | Sep 03, 1999 07:14am | #7

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   ditto from an engineer. I doubt the local building officials ever saw a plan. BTW, what seismic zone are you in? What exposure level do you have for wind? What basic design speed are you using? You need to (for the safety of the inhabitants of your home), go through some basic shear wall/diaphragm lateral loadings and calculate what the required structural retrofit is required. In other words, hire an engineer.

6. 
   Guest_ | Sep 06, 1999 08:25am | #8

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   This may be a good time to move into the garage! Sounds like you openned one big fat huge can of worms here. If I had to guess on whta to do I would say.....You may want to add some walls within to help restabilize things. Even if they are just short walls such as breaks between rooms. glue and screw all your plywood where you add it and do the same to any interior walls you add. I do think the best advice I've seen here is calling an engineer though. Afterall, it is so hard to see your house from way over here.

   Pete Draganic

1. 
   Guest_ | Sep 06, 1999 08:40am | #9

   *Welcome back, Pete. How was the gelato?Mongo

1. 
   Guest_ | Sep 09, 1999 08:42am | #10

   *Thanks Mongo,Had to push that vacation back a few. been too busy to leave..or at least it seems that I have. I guess it's tougher to just break away from things than I thought it would be.Pete Draganic

7. 
   Colm_Toland | Sep 09, 1999 08:43am | #11

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   I am remodelling my house and in the process knocked out the supporting wall on the gable of the house headered it off with four 11 7/8" microlams bolted and nailed together supported by three 6X6 doug fir posts.
   I also removed all the interior walls of the first floor and treated the same with microlams and 6x6's but now in heavy winds I have a slight wobble .
   I do intend to ply the front and back of the house and re-side with cedar siding but am looking for as much advice as I can get.The house is a 1913 2 story frame .