Air bricks & under floor ventilation


Postby 3&33&27 » Wed Aug 24, 2011 9:25 pm

I have bought bungalow which was built in 1954 -The air bricks are concreted over- the previous owner stated this was done when it was cavity wall insulated approx 20yrs ago -
the surveyors report said they needed opening up to provide sub floor ventilation - I have drilled the holes out but it appears there is no air brick or opening in the inside cavity wall ? was it normal in the 1954 not to have "through " under floor ventilation , I am considering just smashing through the internal cavity wall to provide an air flow - any views please ?
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Postby welsh brickie » Thu Aug 25, 2011 7:34 am

you will need to drill through both walls to allow air to flow into the floor cavity.Its best to install as many airbricks as you can.
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Postby xavi99 » Thu Aug 25, 2011 11:42 am

Are you sure it has a suspended timber floor which requires ventilation?

As far as I remember there was a period when cavity walls were provided with air bricks to vent the cavities although air bricks were also provided at higher level aswell.

Alternatively is the inner skin airbrick offset? Air bricks should generally be opposite to provide a through flow of air. If there are air bricks all around the bungalow could it be that some are just 'decorative' and that the adjacent elevation would have inner air bricks? (Hope that makes sense).

Air brick requirements are 1,500 mm2 per m run of wall or 500 mm2 per m2 of floor area, whichever is the greater.

Good luck, hth,

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Postby 3&33&27 » Sat Aug 27, 2011 3:58 pm

welsh brickie wrote:you will need to drill through both walls to allow air to flow into the floor cavity.Its best to install as many airbricks as you can.

Thanks - looks like thats the only way - unfort the cavity is full of insulation & i will have to take a few bricks out to clear cavity & try and get some kind of sleeve in .
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Postby 3&33&27 » Sat Aug 27, 2011 4:01 pm

xavi99 wrote:Are you sure it has a suspended timber floor which requires ventilation?

As far as I remember there was a period when cavity walls were provided with air bricks to vent the cavities although air bricks were also provided at higher level aswell.

Alternatively is the inner skin airbrick offset? Air bricks should generally be opposite to provide a through flow of air. If there are air bricks all around the bungalow could it be that some are just 'decorative' and that the adjacent elevation would have inner air bricks? (Hope that makes sense).

Air brick requirements are 1,500 mm2 per m run of wall or 500 mm2 per m2 of floor area, whichever is the greater.

Good luck, hth,
Thanks for that - yep def susp floor & internal airbrick not there ! Just gona have to smash through .

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Postby welsh brickie » Sat Aug 27, 2011 5:12 pm

[quote="3&33&27"][quote="welsh brickie"]you will need to drill through both walls to allow air to flow into the floor cavity.Its best to install as many airbricks as you can.[/quote]
Thanks - looks like thats the only way - unfort the cavity is full of insulation & i will have to take a few bricks out to clear cavity & try and get some kind of sleeve in .[/quote]


you can buy clay sleeves for the airbricks either 9x3 inch or 9x6 inch
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Postby 3&33&27 » Mon Aug 29, 2011 4:33 pm

Thanks -where can you buy the clay sleeves ? can only find plastic telescope type
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Postby welsh brickie » Tue Aug 30, 2011 7:26 am

usually the big named builders merchants stock them jewsons,travis perkins etc
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Postby 3&33&27 » Tue Aug 30, 2011 12:57 pm

Thanks will try them & let u kno how i get on !
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