Wall Vents New Houses

Just wondering does anyone know why a builder would put a 9inch by 9 inch wall vent into every room of a new house eventhough the windows have vents too.

Thanks

The problem with trickle vents is that they aren't big enough. Regs state they have to be min. 6500mm2 which would equate to about an area of 75mm x 75mm. (3 inch x 3 inch).

The larger wall vents are recommended but not necessary. Wouldn't be as much bother with condensation though at that size (9" x 9")

Thanks for that nutty.

Its actually my friends house and the house is absolutely freezing because of these vents. I know you can get closeable vents but i dont think the building regs allow them

Does anybody know what the story with these vents is when heat recovery ventilation is being used. I'm looking into using this in my new build and it would obviously be a waste of time if you have big holes in the wall.

I know the arguments that HRV works more efficiently in colder climates but I was looking at it more as an air and draught management device rather than specifically to cut heating bills. I currently live in a 5 yr old well insulated bungalow and I hate the draughts that come in the vents and all the lovely heat that gets wasted up my chimney and was hoping not to have to put up with either of them in my new house. I hope that building regs can take account of newer technologies.

there's nothing stopping you blocking the vents with some plastic bags/old towel, this may have other issues but sitting around in the cold is the greater of two evils

Building Regs do not preclude the use of heat recovery systems and this will allow you to dispense with vents altogether. In the case of Lisam, the vents can be replaced with an openable vent (with hit and miss cover). The TGD Part J states that: "background ventilation (may be provided by a) wall or window ventilator with a controllable ventilation grille". As a simple fix the existing vent covers can be simply replaced with the contollable vents. I wouldn't recommend that anyone blocks up their vents with towels or the like- the vents are there for a purpose. If you block vents up permanently condensation may form within the dwelling and cause damage to the structure or contents, unless alternative arrangements are made to ensure that proper ventilation is available.

i was wondering if it possible to put the filters you get in extractor hoods (this is the loose stuff you buy in a bag) into the hole as to prevent draughts but still allow the room to breath

Wouldn't think so johnnyg, this will cut down on draughts alright but it will also reduce the "free area" of the vent, if the filter gets damp the "free area" drops further.

Thanks for that carpenter, I have a copy of TGD J. looks like the builder put in vents that are way too big for each room

lisam said:

Thanks for that carpenter, I have a copy of TGD J. looks like the builder put in vents that are way too big for each room

Click to expand...

Remember that the vent cover size doesn't dictate the size of the vent behind;the vent pipe (sleeve) behind the vent cover may be only a 4" or 6" pipe- this is the important dimension when calculating free area etc.