Main image upload

May 2015

Question

I live in a small terraced house in Dublin that is about 120 years old. My main concern is when vehicles outside go by, I can feel the house shake. My bedroom doorknob makes noise and sometimes in bed I can feel the house shaking, especially when larger vehicles go by. There is a speed bump near my house and the main times I can feel it is when lorries and vans go over it. There is an “RUS 015” three-tonne vehicle limit sign at the end of my road.

I am not sure if is it a structural problem with my house, if the vehicles going up the road are too big or if the road infrastructure needs to improve. We had a structural survey before we moved in a year ago and there was no concern regarding the house.

 

Answer

Vibration is a frequent problem in buildings and can be extremely annoying for occupants. The level of vibration felt from passing traffic depends on the building proximity to the main road, physical road conditions, soil structure, the size of the vehicle passing the building and building construction.

Vibration, like noise, travels via two means: impact and airborne. Traffic vibrations are mainly caused by impact from heavy vehicles such as buses and trucks which produce vibrations with frequencies. When a bus or truck strikes an irregularity in the road surface (speed bump, pothole or uneven manhole cover), it generates an impact load and an oscillating load.

These vibrations can be amplified if the natural frequencies of the soil coincide with any of the natural frequencies of the building structure or its components. This may help explain the strength of the vibrations you are feeling.

Furthermore, a 120-year-old house is unlikely to have separation between the external walls and internal floor construction (floor joists built into the walls); therefore any vibration occurring on the road will pass directly through the building walls and timber floors.

While the effect of building vibration for homeowners can be worrying, vibration levels are rarely high enough to be the direct cause of structural damage. They could, however, contribute to the process of deterioration manifesting as cracks in walls and ceilings.

The maximum gross weight sign, RUS 015, is used where the weight restriction is for traffic management reasons: for example, to prohibit heavy vehicles using residential roads. While the vibrations you experience are not a result of a structural problem, the intensity of the vibration is a result of structural construction. I believe the main contributing factor to the vibrations felt in your home is a result of the speed bumps and would recommend that you contact your local authority to request their removal.

Andrew Ramsey is a charteredproject management surveyor and is chairperson of the Building Surveying Professional Group of the MediKids