Using tile vents for high level ventilation

[jell1234]

Hello,

I have been insulating my attic room at roof level (gabled roof, semi detached house), celotex between rafters + 50mm air gap above.

I have installed soffit vents at the eaves, I now just need to install the high level ventilation. Because there is a void above the ceiling in the attic room, the BCO has said I can use tile vents near the ridge instead of ridge vents. I need equivalent of 5mm continuous ventilation.

I am intending to use the following tile vents: http://www.roofingsuperstore.co.uk/product/harcon-in-line-redland-49-tile-vent-brown.html, positioned at 2m intervals to achieve the 5mm.

I understand I should install these in the second course of tiles from the ridge on only ONE side - so I intend to install them on the rear of the property so as not to be visible from the street.

I also understand I should ventilate around any obstructions, and as I have 2 velux windows and chimney breasts I intend to install one of these tiles either side of these obstructions between each obstructed rafter.

So my question is just - is my understanding correct on these points? Any further gotchas I need to look out for?

Thanks in advance.

 

[colind86]

Installing them 2 tiles down means disrupting the ridge. The ventilation on the velux's at the front will 10x a vent. Are vents really needed?

 

[jell1234]

Hi colind86,

BCO says yes they are, unfortunately. If they are installed three courses down this wouldn't disrupt the ridge, right? I can check whether that is acceptable, but I think it's too low, according to what I've read. How much of a pain is it to disrupt the ridge?

 

[colind86]

3 tiles down generally wont disturb the ridge due to the gauges unless the roofer decided to put a nail in every time he seen a plane (random nailing). If you go 2 down the ridge will no doubt be disturbed. Which will mean prob re bedding 8 ridge due to disturbance.