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Temperature and Humidity Related Expansion and Contraction
Posted by homebild  on December 5th, 2008 05:06 PM
In reply to Knocking coming from attic by geenahme on December 3rd, 2008 09:11 AM [Go to top of thread]
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Moderator Post (s) for this thread:
> Normal by homebild on 12/12/2008 |
The source of the knocking is likely from temperature or humidity related expansion and contraction of roof trusses, plastic vent pipes, or similar in the attic.
Especially if your roof system has been framed using trusses, what you could be hearing is 'truss lift', that is, the lifting of the ends or middles of trusses where they are fastened to the partitions below.
Truss lift occurs when the internal humidity changes within the lumber, causing it to swell and elongate or contract with changes in temperature and humidity.
The phenomenon is harmless.
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You could also be hearing popping or cracking sounds occuring where plastic vent pipes are fastened to and are rubbing against framing members.
As the pipes contract and expand with temperature changes, they move and rub against the wood and can make such sounds.
Given the temperature and humidity changes that go with the colder season and a new house...expansion and contraction of the building materials is the likley cause. Was this post helpful? Yes: or No:
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