air bricks and cavity wall

[sm_jamieson]

Since I don't want crappy trickle vents in the windows of my extension, letting in noise, I have to build in some air bricks. I'll put an adjustable vent on the inside. I wanted to use nice looking 9x6 clay air bricks, but they are 40 holes by 8x8mm, so air flow is 2560mm^2 per 9x6 air brick. Since the regs require 4000mm2 for kitchen or 8000mm2 for habitable room (what for a kitchen diner ?), I would need possibly about 3 of these air bricks. Would look rather over the top. So I may have to use a 9x6 plastic version, with more like slots on the front. I guess it would just look like a fan outlet. But the only 9x6 liner I can get is clay. Surely this would bridge the cavity. Where can I get a suitable 9x6 plastic duct ? Thanks, Simon.

[John Rumm]

How about a pair of:

[sm_jamieson]

I think timloc make these, or very similar. They clip together vertically. Timloc have a 9x6 sleeve designed to be used with two of the plastic airbricks stacked. I'd have to check you can fit 2 of these sleeves when the airbricks or stacked. I think the sleeve fits outside the airbricks, so probably not. Or, I guess, forget about them clipping in properly and just tape them together with gaffer tape and be done with it. The mortar will seal it up ! Or perhaps a very small and annoying online order direct to timloc if they allow. Some of these places have no direct outlet, and their stockists never seem to get in the full range. Have you very tried to order something not normally stocked at a builders merchants ? They act like you are causing them physical pain. Cheers, Simon.

[sm_jamieson]

Well, I got 2 marley airbricks and sleeves, and they fit together fine into a 6x3 block. Simon.