I do not understand App Doc A and Wall length limitations

Eddman · 3 Mar 2024

Hi everyone. So it seems the building regs guys are tightening up on things and requests for further information are growing! I have started to go through all my specification notes and enhancing where required. I am currently looking into 'large masonry panels' and their restraint and such like.

I looked thorugh App. Doc. A and cannot find anything that states the length of a cavity wall (maximum) between butress/windpost/etc. I can see that they (and others NHBC) reference BS EN1996-1-1 for deisgn compliance - but have you read that??? I cannot get my head around what that document is trying to tell me! I cannot find a reference to panel length anywhere in that!

I have also been told by BC that my 'large masonry panels' are unrestrained....i thought that timber floors into the external wall counts as restraint? Am i wrong or do i need to specify more specifically 'restraint type' wall hangers?

I feel like i am back at day 1 of school
!!!

^woody^ · 3 Mar 2024

Walls can be as long as you like.

Floors can provide lateral restraint to walls as long as they are designed to do so. Joist hangers need to be the restraint type.

Read BS 5628, part 1 which may be a shorter read.

Eddman · 4 Mar 2024

Thanks Woody, i have been asked to provide structural "infirmation" for large masonry panels to ground floor extension and two-sroey side extension as these are unrestrained....

You are saying that masonry walls (brick outer 100mm, full fill cav insulation 100mm, blockwork inner 100mm,) can be as long as i like without buttress? I know i will need movement joints if they get too long.

When i spoke to BCO he said it might be that we need wind posts - but why would that be if there is no limitation on the length of a wall between vertical supports?

On the single storey rear extension the roof joists run parallel the the side walls (3m projection) - would this be what he is referring too? as the roof joists will not provide lateral restraint? But i have specified restraint straps from wall plate over three joists...

^woody^ · 4 Mar 2024

Wind posts are not for lateral restraint.

You need to clarify exactly what the issue is. And do this with whoever is checking the plans, not just any inspector.

George_engineer · 7 Mar 2024

Eddman said:
Hi everyone. So it seems the building regs guys are tightening up on things and requests for further information are growing! I have started to go through all my specification notes and enhancing where required. I am currently looking into 'large masonry panels' and their restraint and such like.

I looked thorugh App. Doc. A and cannot find anything that states the length of a cavity wall (maximum) between butress/windpost/etc. I can see that they (and others NHBC) reference BS EN1996-1-1 for deisgn compliance - but have you read that??? I cannot get my head around what that document is trying to tell me! I cannot find a reference to panel length anywhere in that!

I have also been told by BC that my 'large masonry panels' are unrestrained....i thought that timber floors into the external wall counts as restraint? Am i wrong or do i need to specify more specifically 'restraint type' wall hangers?

I feel like i am back at day 1 of school
!!!

Part A has a limitation where walls exceeding 12m would be outside the scope of the document, and internal floor area should not exceed 70sqm.

You may need a structural engineer to confirm that the arrangement meets Part A, else design suitable structural supports.

^woody^ said:
Wind posts are not for lateral restraint.

They are for the masonry panel.

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I do not understand App Doc A and Wall length limitations

Eddman

^woody^

Eddman

^woody^

George_engineer

DIYnot Local

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