Air brick installation

[ajbaker]

Having finally been granted Listed Consent for the installation of an airbrick, I'm not at the stage of considering whether to do it immediately and how to go about getting it done.

Although the house does not appear to be suffering without the air brick, since I am replacing the flooring in the room affected, now seems the most appropriate time to have one/two installed.

The house is a late 1700s terrace with a suspended floor in the lounge to the front of the property. Other houses along the street have airbricks so my suspicion is mine were covered when the lower 40cm of the house was rendered in a thick cementious material. Alternatively it is also possible the pavement has been raised to a level above old air bricks. Either way , my intention is to install one, or preferably two, to ventilate the void and also increase available air for the open fire.

I guess my question is, what is involved with the installation? Is it just a matter of choosing appropriate bricks, cutting a ventilation shaft through the solid wall to the void and installing the brick? Would there be a grill/filter at either end of the shaft (obviously the brick satisfies that on the exterior)? What size should the shaft be relative to the brick?

It is unlikely I will do this job myself - I'm guessing getting hold of an appropriate drill bit for the job would cost more than employing someone to do it? Therefore is a builder the best trade to request for the job?

Any other tips, suggestions, questions very welcome. Thanks.

 

[alice]

I have found when I weigh the cost of special tools for a one-off job and add in the cost of my time and the cost of my inexperience that I am often happier with the result and end up paying less when I hire out.

Of course, then the problem is finding a good person to do the work.

alice

 

[ajbaker]

Sooo true. Sometimes the value of learning outweighs the cost of inexperience, but in this particular case I'm not sure I have the motivation to learn. (No doubt that will change when I receive the quotes!)

 

[NT]

I guess my question is, what is involved with the installation? Is it just a matter of choosing appropriate bricks, cutting a ventilation shaft through the solid wall to the void and installing the brick?

If its a brick wall, the usual method is to remove a brick, plus another one behind, so there is no cutting or drilling of bricks required.

What size should the shaft be relative to the brick?

same size

It is unlikely I will do this job myself - I'm guessing getting hold of an appropriate drill bit for the job would cost more than employing someone to do it?

I very much doubt that, but without details of the vent shape and wall construction...


Any other tips, suggestions, questions very welcome. Thanks.[/quote]

You dont tell us what the wall construction is, which makes a fair difference. Brick wall and stone are 2 different fishes of kettle.

Hopefully you'll find something in character with the house rather than a standard new one.

FWIW another method is to remove the vertical mortar joins every 4th joint, then no separate vent is needed.


NT

 

[ajbaker]

Ah yes, as always I miss the pertinent details.

The wall is of solid brick construction, approx 30-35cm in width.

The pavement is now equal height to the internal floor so removing vertical mortar joints is not possible - this would simply ventilate the room. Speaking of which, how would this help ventilation if you removed mortar from the front row of bricks?

Another problem is the cement render which is approx 40cm above the pavement. Having an air brick above this level would look odd and require a sharply angled shaft to void below. Therefore air brick has to go in render.

Yes I will be purchasing a cast iron air brick that looks similar to the others around here. Having said that, they are all different so that doesn't matter. At least it will not be plastic! After waiting 8 weeks for the council to issue consent for this, they now tell me they want a sample before work proceeds - why the hell they couldn't have told me that 8 weeks ago I do not know.

Thanks so far.

 

[chuckey]

Is there any evidence of an air brick under the floor (in the void)? Standard brick walls are 9", 11" (two brick skins with a 2" cavity), 13 1/2"- three brick skins. Or metric, 225mm, 275mm, 337mm. Now if you are measuring from the inner plaster, add on 1"/25mm for the plaster. if the wall has not got a cavity, the amount of damage you will do, trying to drop a shaft 400mm in a wall of 300mm will be more then I would contemplate.
I would use a metal detector/ nail finder/ magnetic compass and try to locate the original air brick in the outside wall under the render and resuscitate it.
In any case the the shaft must be sleaved to stop your inner wall being at the temperature of the outside.
Just thought if your wall has a cavity, it can be seen in the loft. If it is there, stuff the top of it with glass fibre, to slow the air down through it to reduce your heat loss.
Frank

 

[Nemesis]

1700's houses tended not to have cavity walls.

 

[Matt Green]

Just a quick comment:

Why are you doing this? What problem are you attempting to solve that has you going to this much effort and damage to your building?



Matt

 

[Lime]

Just a quick comment:

Why are you doing this? What problem are you attempting to solve that has you going to this much effort and damage to your building?
Matt

Well, yes, quite.
Having the floor up will reveal any buried air vents.

One or two vents under a damp floor with no cross ventilation isn't going to make much difference either.

 

[NT]

The wall is of solid brick construction, approx 30-35cm in width.

The pavement is now equal height to the internal floor so removing vertical mortar joints is not possible - this would simply ventilate the room. Speaking of which, how would this help ventilation if you removed mortar from the front row of bricks?

Another problem is the cement render which is approx 40cm above the pavement. Having an air brick above this level would look odd and require a sharply angled shaft to void below. Therefore air brick has to go in render.

I see this is more complex than initially said. Looks like more discussion needed.

After waiting 8 weeks for the council to issue consent for this, they now tell me they want a sample before work proceeds - why the hell they couldn't have told me that 8 weeks ago I do not know.

Well, it doesnt take long to put a spatulaful in the little plastic bottle. Dont know what theyll do with it though.


NT