# Truss uplift or foundation movement



## NailBender2 (Dec 15, 2010)

I did a complete house remodel 3 yrs ago on a house that i would call a half berm house, dirt up about 6 ft on 2 sides and cement block walls up 8 ft and a cement floor. the house was built in the 70's with truss rafters. There was an addition, 16 ft long and 28 ft wide added in the 90's that was stick framed including the rafters. there was a beam placed in the attic to support the new ceiling joist over the new opening into the addition and also one below sitting loosely on the cement blocks at both ends. The homeowner wanted a smooth ceiling between the old house and the addition so we removed the beam sitting on the blocks and made sure everything above was secured and fastened together. the ceiling turned out excellent until 1 yr later when a crack developed in the ceiling drywall between the original house and the addition. The crack in the ceiling drywall comes in the fall of the yr and gets worse as the temps outside go down and then in the spring with warmer temps it disappears . We have since put a faux beam across the opening to hide the crack. I had experience with truss uplift and learned that if you try to fix one spot it will show up at another, not sure that is going on with this project since the addition is not truss rafters, leaning more towards foundation movement wondering if anyone else has had a situation like this


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## TimNJ (Sep 7, 2005)

You married stick frame rafters to trusses? That opening and closing with the temperature sounds like truss uplift. In the winter the upper part of the truss is exposed to the cold where the bottom stays warm so they expand and contract at different rates.


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## katoman (Apr 26, 2009)

Yep, what Tim said.


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## one man show (Dec 20, 2010)

two fold problem
expanding and contracting at different rates but nore importantly dont start removing structural members and not have any negative consequences


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## greg24k (May 19, 2007)

What everyone else said...:thumbsup:


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## Theophilus20 (May 19, 2010)

Having had to try to repair a recurring crack like this (Never did know the cause) between old and new biuldings, The best thing that i have ever found for this is to remove 2ft into the old building and remove 2ft into the new building and put a new sheet of sheetrock over the seam.
if the movement is really bad, youll need to do more screws or lags to keep everything moving together as much as possible before you put up the new sheet of rock.
Its just best to try to eliminate that mud seam right where two buildings meet


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## NailBender2 (Dec 15, 2010)

*Truss Uplift or foundation movement*

Got busy during the holidays and didn't get back to anyone,Thanks for your replies> I forgot to put a few things in the first article. When we did the remodel all the insulation was removed and foam was used to insulated,both on the sidewalls and the underside of the roof,not on the top side of the ceiling. This makes the attic almost the same temp as the living area. The cracks seem to be developing more on the side that is not truss rafters and no cracks are developing along the walls in any of the rooms in either part,the old with the truss or the new that doesn't have them. Homeowner wants to try angle iron on each ceiling joist that is over the opening to try and hold it there. I'm afraid if we do that it will crack somewhere else and become a bigger problem than what we have. This is a hard to cure problem but want to do my best to make customer happy but not sure what to do now.


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