airbrick on an extension

nalle59 · 24 Mar 2008

We are having a small extension built to our kitchen .It is built in concrete with 4 layers of brick at the base and thermal block inside with rockwool insulation between the walls.
Now the question is do we need airbricks? The bricklayer got us to buy three airbricks but he has not used them!! The floor will be concreted with damproof membrane and celotex insulation.
Also can someone tell us how the lintel is fixed to the blockwork over the window opening?
Also where does the wallplate go ?and how is it fixed on?
Thanks .

noseall · 24 Mar 2008

is the existing floor of the house a timber floor construction?

nalle59 · 24 Mar 2008

noseall said:
is the existing floor of the house a timber floor construction?

The existing floors are concrete and the new is to be concrete .

Shytalkz · 24 Mar 2008

If he's casting a slab on the ground, there is no void under the floor to ventilate.

Lintel sits on both leaves of the masonry, on either side of the opening.

Wallplate sits on a mortar bed and is strapped down the inside face of the blockwork. It goes under the ceiling/flat roof joists, which are nailed to it.

noseall · 24 Mar 2008

nalle59 said:
Also can someone tell us how the lintel is fixed to the blockwork over the window opening?
Also where does the wallplate go ?and how is it fixed on?
Thanks .

lintels are usually bedded in mortar. they require no mechanical fixings.

normally, the wall plate is bedded in mortar onto the top of the blockwork or the inner leaf of masonry.

noseall · 24 Mar 2008

bah, beaten by shytalkz again.

Shytalkz · 24 Mar 2008

noseall said:
bah, beaten by shytalkz again.

Dah dah, bow to the mastah....

noseall · 24 Mar 2008

Shytalkz said:
Lintel sits on both leaves of the masonry, on either side of the opening.

not necessarily.

window openings directly below a roof overhang, where there is no masonry showing above (i.e. the soffit is laid on top of the window) there isn't a need for lintelling of the external masonry.

nalle59 · 24 Mar 2008

Shytalkz said:
If he's casting a slab on the ground, there is no void under the floor to ventilate.

Lintel sits on both leaves of the masonry, on either side of the opening.

Wallplate sits on a mortar bed and is strapped down the inside face of the blockwork. It goes under the ceiling/flat roof joists, which are nailed to it.

You say the wallplate is strapped down ! with what?

Shytalkz · 24 Mar 2008

noseall";p="862461 said:
Shytalkz said:

not necessarily...window openings directly below a roof overhang, where there is no masonry showing above (i.e. the soffit is laid on top of the window) there isn't a need for lintelling of the external masonry.

Click to expand...

Ok, closed eaves detail, no outer section, give you that: 15 all

Shytalkz · 24 Mar 2008

nalle59 said:
You say the wallplate is strapped down ! with what?

Straps (funnily enough

), usually at 2m centres, L-shaped 900x100, 30mm or thereabouts wide. Short bit goes over the top of the plate and is nailed to it; long bit screwed or masonry nailed to the blockwork.

nalle59 · 24 Mar 2008

Shytalkz said:
nalle59 said:

You say the wallplate is strapped down ! with what?

Click to expand...

Straps (funnily enough ), usually at 2m centres, L-shaped 900x100, 30mm or thereabouts wide. Short bit goes over the top of the plate and is nailed to it; long bit screwed or masonry nailed to the blockwork.

You say the Straps are 900x100 , do you mean millimeters? It seem very long at 900mm , can one use shorter ones?
Thanks for all the reply's much appreciated.

Shytalkz · 24 Mar 2008

nalle59 said:
You say the Straps are 900x100 , do you mean millimeters? It seem very long at 900mm , can one use shorter ones?

well, I wasn't talking inches/feet/metres/miles

. If you're in the wilds of Scotland, or in an exposed position on the coast, then I wouldn't advise it, but there are shorter ones available.

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airbrick on an extension

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