Hi John,
Thanks for your input. Jazz
Any difference would have been between 30-35 year old 1/4" -3/8"(?) very dense Weatherboard (made from highly compressed Fibreglass and other materials)and what is relatively thin Plastic Cladding.I doubt very much that this problem is caused by the difference in the density of the timber and the plastic cladding.
This would tend to bear out what I am discovering in relation to Sound Insulation but please bear in mind Woody's comment.I have seen contractors add layers of high density soundcheck plasterboard to walls to try and attenuate sound and the difference was barely measurable - so a few kgs per metre difference in density between these materials will just not show up.
From the research I have done,and I am no expert, it appears that there are a number of keys to successful Noise Insulation. Acoustic Mats(Or indeed the tarpaulin type material-see previous post) combined with Good Sealing and the use of Airgaps appears to deliver the best results.PVCu weatherboards can come in solid or hollow profile. Solid is better for sound insulation.
I knew I had to eliminate the windows but they are fairly new and to a good spec which I researched and determined before they were fitted. The company that fitted them sent out their specialist and I examined the windows with him and we jointly eliminated the windows.You are probably getting more sound through your windows than anything else. Are your window seals in good condition? If not fit new ones. The rule of thumb is that 90% of sound travels through 10% of gaps. So it's gaps you're looking for. Find em and fill em.
No I am able to confidently eliminate this as being a factor.It's also quite common to get road noise transferring through roof eaves vents and down through thin ceiling boards. Could the contractors have disturbed the mineral wool insulation within and near the eaves area?
Thanks for your input. Jazz