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  1. #1
    Join Date
    Jan 2013
    Posts
    26

    Default Re-Supporting Kitchen Ceiling / Roof

    FACTS:

    House Built: 1915
    Room Span for supports: About 14-15 ft (wall to wall)

    Hi All,

    So I just had my flat (slightly pitched) first floor roof replaced which so happens to be over my kitchen (both were extensions onto the original house) Nothing above the roof.

    So with that I decided to replace my kitchen ceiling as well. I had the usual drop ceiling grid with the lath/plaster. So I got rid of all that and am now down to the wood supports.

    The joist structure is a two tier structure with one tier (top tier) of 2x8 supporting the roof which sit on the shoulder plates of the kitchen structure and the other tier (lower tier) is made of 2x6 joists which support the ceiling. They sit on (or rather are etched into) 1x2's which are nailed into the shoulder plates

    Now I have two problems:

    1). The tip tier joists sit about 24" apart on center. Not sure if this is a typical setup. The middle joist cracked straight in half (probably from the winter snow weight). In order to get the roof replaced the roofer simply resupported the cracked joist with 2x8 pieces so they could apply the plywood board, but now I need to either sister this middle joist or add 2 new 2x8 joists (one on either side of it) to properly support the middle load.

    Any ideas on the best course of action for this is appreciated?

    2). My lower tier joist support system for the ceiling is sitting on 1x2's. Quite flimsy for my taste and they wobble like crazy. Yes they have been like this since the kitchen was built some 50 years ago and yes my new ceiling will be lighter then the old one, but now that I have it open I want to resupport them and get rid of the side to side wobble and slight vertical wobble.

    Any idea how I should go about doing this?

    Thanks all for any ideas you may have for me.

    P.S. In case anyone is wondering about new ceiling weight I plan on putting some 6" recessed lighting around the room perimeter and a ceiling fan in the middle.

  2. #2
    Join Date
    Jan 2010
    Location
    Northern Virginia
    Posts
    1,301

    Default Re: Re-Supporting Kitchen Ceiling / Roof

    2x8's on 24" centers spanning 14-15ft is structurally inadequate and would not meet code. You need no more proof of that than the fact that one joist had failed; which means that there is now more stress on the adjacent joists, which can lead to a cascade-effect failure. Not good for people underneath.
    You need a structural engineer to spec out what size and spacing of new material can be put in to salvage the situation, and how to fasten them properly to make it safe.
    Casey
    Remove not the ancient landmark, which your fathers have set.

  3. #3
    Join Date
    Jul 2010
    Location
    SoCal
    Posts
    7,344

    Default Re: Re-Supporting Kitchen Ceiling / Roof

    Quote Originally Posted by Sombreuil_mongrel View Post
    2x8's on 24" centers spanning 14-15ft is structurally inadequate and would not meet code. You need no more proof of that than the fact that one joist had failed; which means that there is now more stress on the adjacent joists, which can lead to a cascade-effect failure. Not good for people underneath.
    You need a structural engineer to spec out what size and spacing of new material can be put in to salvage the situation, and how to fasten them properly to make it safe.
    Casey

    Casey,

    About 10 years ago I built an addition in a house (which was built in 1959). Plans called for 2x6 rafters 24" oc to match existing framing, with 14' span. All existing rafters were in perfect condition, and there are 3 layers on the roof (of course the addition has 1 layer). No problem.

    The OP stated that his house was built in 1915 and has 2x8 rafters 24" oc. We don't know the cause of the split in that one rafter and we can't really speculate. In my city there would be no need to upgrade.

    Sure you can call an engineer. I wouldn't. But I might go down to the bldg dept to verify.

  4. #4
    Join Date
    Jan 2010
    Location
    Northern Virginia
    Posts
    1,301

    Default Re: Re-Supporting Kitchen Ceiling / Roof

    She stated it is a flat roof, and she admits that the snow load caused one joist to fail already. 2x8 at that spacing and span is undersized accoridng to the joist span tables factoring in a 50lb snow load, and the failure makes my point better than arguing about it.
    Casey
    Remove not the ancient landmark, which your fathers have set.

  5. #5
    Join Date
    Jan 2008
    Posts
    2,478

    Default Re: Re-Supporting Kitchen Ceiling / Roof

    In the old days the carpenters were usually pickier about their lumber which was generally better in grade than todays, so while this may have been a weak rafter cracking, the spacing might have been adequate wityh the original roof design. Being that the roof is now complete my solution is moot, but I would have replaced than all with 10" or better at 16" centers before putting the new roof on. Too late to do that now which leaves us needing to give them all better support- not just the damaged one. If there is adequate space perhaps running a beam under the rafters near mid-run will be sufficient. Alternately a new 10" ceiling joist system could be installed with stiff-knees run up near mid-run to support the rafters better. Nothing is going to help the 24" rafter spacing so this is about all that can be done without losing a new roof. If you do go with the new wider ceiling joists they will need either a solidly designed ledger to sit on or a similar band to attach to using joist hangers to carry the load. And their spacing will have to be directly under the rafters so extras will be needed to maintain a 16" OC ceiling spacing too.

    Sorry to have to say this but the questions came too late for a proper and easy fix which could have been done while the rood was being worked on. So now you get to do a huge amount more than would have been needed. And you seem to have another roof like this based on your post- guess what? You're probably going to find the same issue there. Or you could take your losses as a learning experience, rip the new roof off and do them both properly this time. That's what you really should do but it's your house so you do whatever you please- I won't be there in the winter anyway so it won't come down on me!

    Phil

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