Truss uplift is a phenomenon that occurs in a home with a truss roof system (see above picture). In cold weather the bottom chord of the truss stays warmer and drier than the other the members, because it is closer to the heated area below. The other members expand at a different rate than the bottom chord, so it bows upwards, pulling the ceiling up with it.
It looks like this from inside:
Yikes – someone seeing that for the first time might assume that it is a serious structural problem! Don’t worry, though; there are ways to correct it without major expense.
There are a few solutions for this problem:
1. Adequate Attic Ventilation: By preventing a build-up of moisture in the attic, you effectively control expansion of the wood framing members, and lessen their movement during cold/hot weather.
2. Install Sliding Clips: These brackets allow the truss to move up and down without pulling anything along with it.
3: During Construction: Some builders are securing the ceiling drywall to the top of the walls, and not attaching to trusses for a distance of 18 inches from any wall.
4. Install crown moldings, but fasten them to the ceiling only, not the wall. Then when the ceiling moves the molding travels up and down with it, hiding the movement! This is also a good excuse to impress visitors with your interior design skills.
Does your home inspector know what to look for when he sees a crack in the ceiling?
About the Author: David Fairbairn is a licensed, insured, Certified Home Inspector in the province of BC. and holds a certificate in home inspection from Ashton College in Vancouver.
He is also a licensed Power Engineer in BC, and holds a certificate in power engineering from the McPhail school of Energy at SAIT in Alberta. He has been involved in the construction, maintenance and repair of luxury and high-end commercial buildings in downtown Vancouver for many years.
He has a common-sense approach to building science and an innate ability to explain complicated concepts in clear terms.
Call now to book your home inspection! 604 395-2795
Author David Fairbairn is a certified, licensed home inspector serving Vancouver and the Lower Mainland. He has been featured in the media and has contributed to "24" Newspaper, and Global TV. He has spent years working with residential and commercial building projects, and holds a Power Engineering License in BC. Why not give him a call for your next Home Inspection? Call 604 395-2795 or email firstname.lastname@example.org today!