Air bricks

25 Jan 2019
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United Kingdom

I have an end terrace house circa late 1920s

I wish to install two air bricks along the side elevation of the house. The house has one air brick installed along the side now

· Engineering bricks used

· Existing normal Bricks 235 mm wide x 75 mm high

· Existing Air Bricks 225 mm wide x 160 mm high

· Black Ash Mortar used on original bricks

· Original DPC is 2 bricks above paving (in fact about 2 1/4 bricks above paving). Original DPC is a hard bitumen like sheet

· Original air brick starts at paving and finishes at two brick up with original DPC directly above it

· Chemical DPC injected into 4th brick above paving

· Floor level begins at just after 3 brick up

Where can I get Air Bricks 225 mm wide x 160 mm high

I can get air bricks 215 mm x 140 mm, will it matter, presumably mortar will be used to cover the gap

The top of the air brick will be at the level of the original DPC (like the existing air brick) and therefore I assume DPC will be damaged when removing the brick below. Will the DPC have to be reinserted above the removed brick and how is this done

What mortar should be used. I read that mortar should not be harder than the brick or brick will be damaged.

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Thanks Ken

I am looking for the larger size air bricks.

I had seen the Wicks air brick

However this air brick will add another 10mm of mortar to the top and bottom of the brick, this is in addition to the existing mortar, so I will finish with 20mm mortar top and bottom. However, it does look like I will have to go down this route

Has anyone any thoughts and dealing with the disturbed DPC?
Best to use the 215 x 65 which will only need 1 brick removing in the outer and inner skins thus you won't be disturbing the DPC. (I've assumed solid full brick walls here). Might be worth sleeving through the inner skin- there won't be much of a cavity and the DPC should be blocking it but for what it'll cost in materials and time (about £3 and 5 minutes) it'll avoid adding any random draught problems through and up the wall. Mortar to fill the gaps in the outer wall, exp foam to seal the sleeve into the 'cavity'/inner skin and to the airbrick itself
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Thanks oldbutnotdead.

Yes its a solid wall

I had thought to use 215 x 65 air bricks. However, looking at the British Standard I calculate I need in the order of 5 "double air bricks" 215 x 140 installing to obtain the ventilation required. I settled on 3 "double air bricks" in the end, with two going on the side of the house. If I went down the "single air bricks" route I would need to install 6 to do the same job, so I am a bit reluctant to do this.
Fair dos. You'll find it is much easier to neatly remove a single brick 6 times instead of 3 whole bricks and 6 half bricks. Also check the airflow on the plastic ones woody linked to, you may find you only need 3 of them :)
Yes the air flow rate of the plastic airbrick (as compared with the square hole clay airbrick) is almost three times more
It appear that even if I install a single air bricks 215 x 65 I will need to install air bricks directly below the DPC. Can or should the DPC be restored when the air brick is inserted. If I need to restore the DPC how do I go about doing it.
How very irksome. Best bet- when you chop the existing brick out, stitch drill the bottom bed and the 2 perps and leave the top alone- with luck the bitumen will stay in one piece. If it doesn't then clear it out and either use a piece of slate (if you have any kicking around) or plastic DPC (you can get wide rolls of this which will fully cover imperial brick) or don't worry too much if you're using plastic airbricks- they are non permeable.
Thanks oldbutnotdead

Yes the paving rises along the side of the house and the brickwork below the DPC narrows to 1 1/2 bricks tall. So not option but to have the single airbrick directly below the DPC here

Thanks, thats good advise

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