Roof/ ceiling shudder possible pressure wave

[Jamie3019]

I'm having a serious problem with double decker busses passing approx 3 meters from the front door. I'd expect a certain amount of vibration but but as these tail of what I'm also getting is a horrendous jolt/ shudder coming from bedroom ceiling. Sounds like a loud creaking/ cracking sound. It's only recently when I've been in during the afternoon I have got to witness this and narrow it down to the ceiling/ roof.


Bernardgreen answered this in the loft forum with 'a pressure wave is the likely cause. Especially if there are no soffits fitted. The pressure wave would get into the attic space and cause a pressure differential between attic and bedroom and thus a downward deflection of the ceiling. If the eves of the roof are open then there would be nothing to stop the pressure wave getting into the attic.


I have attached a picture of my roofline to see if anyone could possibly add to this and what steps I can take to prevent it. It's driving me to distraction to the point I'm now sleeping in the box room at the back of the house. The loft is uninsulated and not boarded. Would this make a huge difference?


Thanks in advance.

 

[Lower]

Insulating your loft will benefit you in lots of ways. Noise absorption will be a major one, as will reduction in heat loss.

 

[bernardgreen]

There appears to be a significant gap between the stone work and the facia. If it is a clear gap then a pressure wave ( or strong wind ) would get through it and into the loft space.

If there is no felt inder the tiles then that is another entry route for wind and/or pressure waves

 

[^woody^]

Unless your bus company is using Typhoons as a bus, I am not conviced with the pressure wave from a bus theory.

 

[garyo]

Try putting a few medium weight boxes in the loft on the plasterboard and joists to see if changing the ceiling mass has an effect on the resonance and the sounds. If that has an effect then you know what you're dealing with. Have you been up there to look for loose mortar, and enormous colony of scared bats, etc?

 

[Jamie3019]

Any thoughts on what you think it might be woody?

Good idea thanks Garyo. Yea I've been up and had a nosey but not entirely sure what I'm looking for. I'm shocked that a double decker can cause so much resonance on a structure but is everytime they go past like clockwork. I need to get to bottom of it asap.

 

[datarebal]

If you have underlay on your roof (below the tiles or slate) Have you tried waiting in the loft to see what happens when a bus goes by?
loose laps can make slapping ..buzzing even banging noises. I have seen this in areas subjected to harsh weather where laps have not been secured correctly.
Even at gutter level on the outside if no support tray is used.
Maybe the pressure wave from the buses are causing this to happen.

 

[^woody^]

Any thoughts on what you think it might be woody?

Get a bus timetable and sit in the roof to have a listen and a look. It's difficult to pin down structural noise problems, but essentially, the structure should not be influenced by a passing bus, and certainly not by a dramatically coined "pressure wave" from a bus. If it's movement of air from a bus, then why not from a gust of wind?

Narrow down the material cause of the sound first and then you can deal with that.

For the actual source, some things to consider - is it busses but not large lorries? Is it the resonance of the engine or the movement of air? Is it at speed, idling or pulling away?

 

[Ian H]

Might be easier with 2 people

 

[Mw Roofline]

Are there any drains or dips in the road right outside that the bus hits and sends a vibration through the house? Try opening the windows and then listen, if it goes away then yes could be pressure forcing up the wall. Or build a speed hump outside.

 

[Jamie3019]

Race back from work but Sod's law had it I missed the last bus. Typical. Got some pics though and it did seem very windy up there. No sign of any movement but as I say didn't manage to catch any busses. Does it look like there is enough support for the rafters etc?

Thanks

 

[datarebal]

ok not an underlay issue... Slate roof with most of the torching still in place .
Rafters appear skinny but the purlin looks substantial .
wait for next bus

 

[crank39]

Ask for a bus stop outside your house, that should cure it

 

[^woody^]

You've got no underfelt, so the loft should be pretty leaky in terms of air. This would imply very little resistance to air movement, so no choke points for any "pressure wave".

BTW, if you do get home before the last bus, when you are in the loft, you need to have the loft hatch closed, otherwise you are altering the internal pressures of the house and the loft - leading to different circumstances and potentially different results.

 

[garyo]

Have you ever seen that film 'shallow grave'? Maybe you have someone up there?