air vent pipe size

ashland_83

Hi All,
I'm having an extension done on the back of the house and my builder has put down two 50 pipes from the current air vents to go through the concrete wall and then to the new wall. Someone told me that 50 is too small and this should be at least 100. Does anyone have any idea? is there any regulations?

Thanks

MX5huggy

It will depend on the length of pipe, and the area to be ventilated. Maybe ask your building control officer.

brightontraveller

That depends on purposes of pipe/ ventilation etc what it vents and to an extent size, type of fan( if a fan is needed at all ) etc.
Reg for bathrooms kitchens, passive stack etc More about extraction rates l/s etc I,m suspicious when "builder" fits pipes its often an area the have little or no knowledge in and 50mm points more to that than them being so? Most are 100, 125 150 otherwise your faffing around adding parts reducers etc (if they exists) that are often inaccessible more to go wrong ideally one pipe no joins or as few as possible....

Ask him why 50mm then post reply i'd imagine it will be BS answer

Kiran

Are you talking about the air bricks or an extraction vent? If its something powered by a fan then reducing the pipe size from 100 to 50mm will restrict the air flow and make the fan work harder. I might be looking at this incorrectly as I can't quite work out what you are describing

MX5huggy

I took it to mean there is an existing suspended timber ground floor which has air bricks to ventilate under it. The extension will have a solid floor so the pipes are to maintain the ventilation to the existing floor.

brightontraveller

MX5huggy wrote: »

I took it to mean there is an existing suspended timber ground floor which has air bricks to ventilate under it. The extension will have a solid floor so the pipes are to maintain the ventilation to the existing floor.

I thought so too but do they do an adapter from air brick to 50mm? I’ve seen plenty of round 100, 125, 150mm and very occasionally 75mm (verplas type stuff) not ever seen 50mm didn't think flow etc would be sufficient through it?

MX5huggy

When I had mine done there was no adapter required as the wall with the air bricks was coming out with a RSJ above so the wall came down below floor level and two gaps made to run the pipes in to the floor void. What I don't remember is the size of the pipes.