Beam & Block - Cross Ventilation

[Mulberry View]

I'm planning a 150mm void under my Beam & Block. Was going to achieve this with 440x215x140 7N dense blocks laid on their backs. This also provides me with a 215mm wide bearing to assist with the narrow beam spacing (so the beams can be laid without clashing).

 

If I lay the sleeper walls in one course as described, how do I provide cross ventilation? Or do the gaps between the beams suffice?

[Mr Punter]

With some beams, once the blocks are in you only get 50mm left, but that should still be plenty.

[Mulberry View]

8 minutes ago, Mr Punter said:

With some beams, once the blocks are in you only get 50mm left, but that should still be plenty.

 

Mine at 175mm beams, the base is 75mm deep. That said, I do have an awful lot of beams. 🤣

[nod]

4 hours ago, Mulberry View said:

I'm planning a 150mm void under my Beam & Block. Was going to achieve this with 440x215x140 7N dense blocks laid on their backs. This also provides me with a 215mm wide bearing to assist with the narrow beam spacing (so the beams can be laid without clashing).

 

If I lay the sleeper walls in one course as described, how do I provide cross ventilation? Or do the gaps between the beams suffice?

For this reason you should definitely be more than 150 

[Mulberry View]

37 minutes ago, nod said:

For this reason you should definitely be more than 150 

 

For what reason? Do you mean so that I can build the vents into the sleeper walls?

 

My drainage design is super simple in layout, but sadly it's all got to go in trenches inside the footprint, so there's nothing else to go in the void.

 

As I said in one of my other posts, the drop in void enables me to increase the insulation.

 

Genuine question, why keep the void at 225?

Edited November 9, 2022 by Mulberry View

[nod]

Our build and our previous build have been on clay So a 225 minimum would be a minimum I dug out to allow 400 to get some drainage under this time 

But yes 150 makes it difficult to add letter boxes 

 

pictured is our previous build 

[Canski]

You could leave a 610 mm gap between the b140 blocks and put one course of bricks down then a 600 x 100 x 65 mm lintel on that then you will have a letter box and a support for your beams. Although I think the 50 mm gap would suffice unless you are building on top of the sleeper walls in which case the void should be filled with brick slips anyhow.

[Russell griffiths]

Or you could do this. 

[Canski]

he only has 150 mm to play with

 

[Dave Jones]

there will be gaps under every beam all along the sleeper wall.

 

Any additional ventilation requirement, and location of the perimeter vents, will be on the block and beam drawing.

[Mulberry View]

3 hours ago, Dave Jones said:

there will be gaps under every beam all along the sleeper wall.

 

Any additional ventilation requirement, and location of the perimeter vents, will be on the block and beam drawing.

 

Thanks for you help everyone. I have decided to build using the 140mm 7N blocks to a total height of 150mm. Although BC were happy for the cross ventilation to occur via the gaps under the beams over the sleeper walls, this will not work as several are load bearing, so I learn will need to be fully infilled. I've put 110mm soil pipes in as cross-vents at an average of around 1 per metre. These will have around 40-50mm of concrete over the top of them and have been placed as best as possible to avoid a beam bearing positions. I will reinforce over the top of the soil pipes with rebar grooved into the blocks and bedded in the concrete as an additional security (I have a fairly big pile of 10mm rebar in 400mm lengths leftover from the Geocell driveway job, I have no other use for them).

 

Hopefully that's enough.