Cavity closer

[Moggaman]

Hi. Please see detail provided to me regarding area around eaves. My design does not have a cavity closer. The insulation will run up to meet the rafter insulation. Just wondering if the cavity closer has any structural properties or is it just there to ensure nothing gets down into cavity. If so, would a few more wall ties on the last course be warranted?. My question is not around whether is complies but around the reasoning for having one…

 

thanks .

[ADLIan]

Cavity needs closing at top for fire safety - see appr doc B

[Dave Jones]

it doesnt, but it is good practice i guess.

[ADLIan]

See appro doc B. Not sure what an alternative approach would be especially post Grenfell

[Oz07]

Never closed one on a single detached house in my life. Perhaps i've been doing it wrong

[Oz07]

Maybe there's a difference when using full fill batts/wool or bead versus ventilated PIR insulation cavity

[Dave Jones]

19 minutes ago, Oz07 said:

Never closed one on a single detached house in my life. Perhaps i've been doing it wrong

 

 

you havent.

 

 

[ADLIan]

Sorry to be repetitive. See appr doc B ( relevant section has not changed for many, many years)

[Dave Jones]

38 minutes ago, ADLIan said:

Sorry to be repetitive. See appr doc B ( relevant section has not changed for many, many years)

 

could you quote the relevant section to enlighten us wrongdoers.

[ADLIan]

5.16

[Moggaman]

Is fire safety the only reasoning?. For those of you that didn’t close the cavity at wallplate level, do u increase wall ties at wallplate level 

[tonyshouse]

No, carry insulation up the cavity to seamlessly join with loft/roof insulation 

 

closing the cavity in masonry construction is likely to introduce a thermal bridge 

[joe90]

3 minutes ago, tonyshouse said:

No, carry insulation up the cavity to seamlessly join with loft/roof insulation 

 

closing the cavity in masonry construction is likely to introduce a thermal bridge 

Exactly, and wot I dun (with knowledge of my building inspector). Note, I used rockwall full fill batts. Perhaps the regs are intended for vented cavity.

[joe90]

1 hour ago, Moggaman said:

Is fire safety the only reasoning?. For those of you that didn’t close the cavity at wallplate level, do u increase wall ties at wallplate level 

No

[Gordo]

On 13/08/2021 at 22:19, tonyshouse said:

No, carry insulation up the cavity to seamlessly join with loft/roof insulation 

 

closing the cavity in masonry construction is likely to introduce a thermal bridge 

Best close cavities with polythene enclosed rockwool strips (cavity barriers) Compression fit between tops of two leafs

Edited October 30, 2021 by Gordo

[Dave Jones]

On 13/08/2021 at 17:12, ADLIan said:

5.16

 

only relevant to multi property storied buildings. Not single occupancy houses.

[ADLIan]

Thanks Dave. Can you reference that statement please?

[Dave Jones]

Just now, ADLIan said:

Thanks Dave. Can you reference that statement please?

 

just read the regs 5.16

[ADLIan]

I still cannot find any reference to differentiate single dwelling or multi storey/multi dwelling