Coursing maths for airbrick positions.

[epsilonGreedy]

I am about to lay the inner wall telescopic portions for my suspended floor ventilation. Should I think ahead and ensure that when these vents are mated with airbricks the positioning of airbricks occurs at whole brick boundaries in the outer wall?

[Mr Punter]

Can you leave a wider gap on the inner leaf so you have a bit of room for adjustment?

[epsilonGreedy]

1 minute ago, Mr Punter said:

Can you leave a wider gap on the inner leaf so you have a bit of room for adjustment?

 

 

Not sure I am following this advice. The problem as I see it is that the block & beam floor will be down before the outer wall reaches dpc height and it is time to fit the airbricks.

[nod]

It’s much easier to build your outer skin up before the B&B goes in 

I set mine every eight bricks But moveved around a bit to keep them looking uniform near corners etc

[epsilonGreedy]

3 minutes ago, nod said:

It’s much easier to build your outer skin up before the B&B goes in 

 

 

Ok. My thinking was a higher outer wall would be at risk from collision as beams are maneuvered plus if this is done manually the beams need to be lifted higher.

I am not committed either way yet.

 

Are there other benefits for doing the outer skin first up to dpc which in my case is 300mm aove ground rather than a standard 150mm.

[PeterW]

3 minutes ago, epsilonGreedy said:

 

Ok. My thinking was a higher outer wall would be at risk from collision as beams are maneuvered plus if this is done manually the beams need to be lifted higher.

I am not committed either way yet.

 

Beams are very heavy and not easy to shift about even with a Telehandler.

 

All but the small ones will breach manual handling limits and you will probably need machines to offload as some deliveries don’t use hiab equipped vehicles as beams can exceed the hiab limits. 

[epsilonGreedy]

1 minute ago, PeterW said:

All but the small ones will breach manual handling limits and you will probably need machines to offload as some deliveries don’t use hiab equipped vehicles as beams can exceed the hiab limits.

 

 

Useful info, thanks.

 

Most of my beams will be sub 3m due to a timely conversation with my self build neighbour the evening before the digger arrived to excavate the foundation trenches, as a result I decided to incorporate an extra trench mid way down the sitting room. My longest beams will be 4.2m.

 

I am planning on the basis of 33kg per meter which means once a telehandler has lowered a beam onto the inner wall bearing, one end can be shuffled by lifting the weight of 2 heavy holiday suitcases.

[nod]

20 minutes ago, epsilonGreedy said:

 

Ok. My thinking was a higher outer wall would be at risk from collision as beams are maneuvered plus if this is done manually the beams need to be lifted higher.

I am not committed either way yet.

 

Are there other benefits for doing the outer skin first up to dpc which in my case is 300mm aove ground rather than a standard 150mm.

We did the in and outer to dpc level 

and simply lifted the beams in and lowered them onto the inner skin

None of the face work was disturbed Two hours and they were all in 

[epsilonGreedy]

2 minutes ago, nod said:

None of the face work was disturbed Two hours and they were all in 

 

 

Good to know, I suppose outer-first will be kinder to the brickie's back if the outer engineering face bricks can be laid while standing on the lower ground oversite.

[Mr Punter]

1 hour ago, epsilonGreedy said:

 

Not sure I am following this advice. The problem as I see it is that the block & beam floor will be down before the outer wall reaches dpc height and it is time to fit the airbricks.

 

You can leave a space of 325mm for the vents on the inner leaf rather than building them in tight, so they can be moved side to side to fit the brickwork.

[epsilonGreedy]

22 minutes ago, Mr Punter said:

You can leave a space of 325mm for the vents on the inner leaf rather than building them in tight, so they can be moved side to side to fit the brickwork.

 

 

In view of the point loading from a beam end can this technique only be applied on opposing walls not bearing the beams directly?

Edited August 29, 2018 by epsilonGreedy

[nod]

20 minutes ago, epsilonGreedy said:

 

In view of the point loading from a beam end can this technique only be applied on opposing walls not bearing the beams directly?

We used a crane Most most of the beams were over six mtrs 

[epsilonGreedy]

2 minutes ago, nod said:

We used a crane Most most of the beams were over six mtrs 

 

 

My concern with leaving 325 gaps for duct inlets in the inner blockwork is that a beam end could end up sitting directly over the 325 gap just 2 courses above.

[nod]

1 hour ago, epsilonGreedy said:

 

My concern with leaving 325 gaps for duct inlets in the inner blockwork is that a beam end could end up sitting directly over the 325 gap just 2 courses above.

Agreed making a lot of work not putting the ducting and air bricks in first 

[Mr Punter]

We only put the air bricks first on a project with Beamshield special insulation blocks that wrapped underneath the floor beams and I understood that external brickwork would get in the way.  We put lintels over the vent gaps on the inner leaf.

[epsilonGreedy]

54 minutes ago, Mr Punter said:

We put lintels over the vent gaps on the inner leaf.

 

 

Ok I can picture this now, something to consider. Is it common practice to take special measures when beam ends are sited near air brick vents?

 

Underfloor void ventilation building standards must cope with terraced houses, I wonder if the whole issue can be sidestepped by fitting air vents on opposing walls at 90 degrees to the beam orientation.

 

Taking into account all responses here I reckon I will put in the first two courses of below dpc facing bricks. This will then provide a gauge for positioning the inner ducts and in addition I will ensure the ducts are positioned within the 500mm pitch of the beam spacing. I might even take the facing bricks up to 6 courses high before swinging the beams into position because having laid 80 trench blocks for the garage I am full of empathy for the brickie's back.