Cutting Bricks out internal central wall & Air bricks?

[lovelyjob]

Hi all. Had some good advice recently about replacing my suspended timber floors. I'm now at the stage of looking to get max ventilation to the 2 ground floor rooms.

First question relates to the staircase walls that separate the front and back room (typical victorian terrace)see plan.Originally there was no flow through these walls, so the air bricks front and back would only get air into the respective room without a flow front to back of the house. Hopefully you can see on the pic (which shows the staircase wall & walk through doors on the left and right to the front room, from this backroom) that there are some removed bricks where the heating and electric come through the wall under the door on the right. This was originally done for the services and nothing to do with ventilation. I was thinking of repeating this under the left doorway also (Both walls of the stairs front and back obviously). Firstly, do you think this is safe structurally as these walls are 2 storeys high, double brick...and secondly, can I remove a brick...maybe 2...in the central area of the wall (both sides of stairs again) to really help air move through. I am slightly worried about compromising the stability of the wall above here. I did think that I could add one of those clay cavity spanners into the brick work to give me some stability back...or is it not a problem? The walls are just double brick thick with no cavity.


Other question regards the air bricks to the external walls. The front walls have 2 non original grills, which are so high that the air passes over the Floor level as well as below...and the rear has only 1 original clay air brick, which I am thinking to change to the plastic type. I have read that the new plastic type give more flow than the original clay type. I just wondered again about the stabilty of the walls...on plastic vents? I assume this is not a problem or they wouldn't sell them...any thoughts to put my mind at rest please.

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• lovelyjob
• 5 Aug 2014
• 2

VIEW D

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• lovelyjob
• 5 Aug 2014
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FLOOR PLAN

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• lovelyjob
• 5 Aug 2014
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VIEW B AIR VENTS

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• lovelyjob
• 5 Aug 2014
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VIEW A DETAIL

 

[LanceCorpralJones]

You do need ventilation from one side to the other, (or front to back) so ventilation in the dividing wall is required. The amount of air bicks should be the same number (and size) as the external air bricks.
They should be positioned to encourage ventilation to all corners of the sub floor.

The amount of bricks removed to accomodate air bricks is of no concern.

Plastic vents are fine. The vents should be those designed for double skin walls, if that is what you have.

It's of no concern if the vents are designed for cavity walls but yours are no-cavity walls. The vent is below floor level so won't be visible.

Often internal dividing walls are constructed in a honey-comb fashion.

 

[lovelyjob]

Thanks Corp'ral...When you mention honeycomb to central walls..I suppose thats what I am thinking of doing now. I wasn't thinking of putting air bricks there...just leaving the brick width gap...aka, honeycomb. Is this ok re structure above?

Unfortunately I'm kinda stuck with the existing air brick external positions...if you see photos....Not much room to put elsewhere! (I suppose you're suggesting that balancing the air brick size and mirroring positions to effect the most draft). The rear wall is a real problem..only one air brick. So I want to change to the plastic...to at least get as much air in as possible. The front 2 air grids are way too high...allowing air flow on top of the floor...No wonder my feet were like ice last 2 winters. I did change the front joist ends about 8 yrs ago, as they were rotten, and looking at them today, the air grids do work, as the timber is still dry with not a hint of damp or rot. I had little knowledge then and just used treated timber for joists, sitting on a new treated wall plate...no dpm...and all still looks well. Proves the effectiveness of ventilation. I will try to slip a dpm under the wall plate. (The joist ends are an inch away from the walls...so I did at least know about them not touching)

I've cleared out loads of earth, rubble and general **** from under floor, so though the flow will never be perfect...but it's going to be much improved. Celotex inserted between joists also, which should focus draught in the void below... 8" available below joists in the front room and about a foot in the back room. Getting air flowing to the corner zones is nigh on impossible, particularly the alcoves either side of chimney breasts..notorious for the damp there!

Thanks for the reply. Very helpful.