Do I need piers in my block wall?

[bulb763]

I'm having a detached garage built. Sized and constructed so that building control aren't interested. The slab that it is to be built on measures ~9m x ~3.4m. ~2m high walls. Sheltered by 6ft garden fencing. I want to get the max internal width possible so I had bargained on single skin 100mm blockwork, with the possible inclusion of 1 or 2 piers along the 9m length.

I've had a couple of brickies look at the job and the first (aged 50s ish) agreed that a single pier would be adequate. He also suggested an alternative: that using masonry mesh every other course of blocks would provide sufficient strength that a pier wouldn't be required.

The second guy (late 20s ish) said he would include 2 piers along each 9m wall and didn't mention any mesh alternatives.

A third guy is coming to look tomorrow. In the meantime though, what would the PH advice be regarding piers / masonry mesh? I like the sound of the mesh since it gives me the max internal width with no (albeit only ~100mm) pier intrusions. However I dont want the whole lot to fall over at the first sign of a stiff wind. Google suggests piers should be every 3m max. What if I used 140mm blockwork? Would a 9m long wall built with 140mm blocks without piers be strong enough with / without mesh? Any other sugestions to maximising the internal width while maintaining sufficient strength?

Cheers for any advice

[mk1fan]

Including the mesh would negate the need for piers. Although, I'd suggest building the corners as piers. The roof structure (if done properly) should add to the overall integrety too.

[ShredderXLE]

I thought the mesh was there to remove the need for movement joints and control cracking - not provide stability which is what the piers are doing. Although exempt from the regs due to the small size, approved document A does have a guide to postion and sizing of piers to resist wind loads in small single storey buildings such as garages.

[Busa mav]

If it were mine I would have 2 piers along a 9m length.

Could you not build the piers on the external face and just increase the slab locally to carry them ?

Mesh will just ensure that the wall stays in a larger piece when it does get blown over

[bulb763]

Busa mav said:

If it were mine I would have 2 piers along a 9m length.

Could you not build the piers on the external face and just increase the slab locally to carry them ?

Mesh will just ensure that the wall stays in a larger piece when it does get blown over

Eloquently put, and just what I was getting at!

Slab is already in place. If I had thought ahead a bit more then I would have included pier bases or just added an extra 200mm width.

I've found the part A structural regs document, looks very useful thanks.

[Use Psychology]

surely the door at the front will be further than 100mm away from the (internal) edge of the walls... therefore the piers aren't going to meaningfully affect the usable internal space? unless you are thinking of workbenches, shelves, etc.

[bulb763]

Use Psychology said:

surely the door at the front will be further than 100mm away from the (internal) edge of the walls... therefore the piers aren't going to meaningfully affect the usable internal space? unless you are thinking of workbenches, shelves, etc.

Exactly. Maybe a pier is the difference between being able to open a car door to the 2nd notch instead of the 1st. Walking past the car without worrying about scratching it. I just figure that every little will help

[Use Psychology]

i now have a mental of image of your car under a pile of rubble because you were trying to avoid a scratch on the door

[bulb763]

[mrmaggit]

Carpet the walls.

[Fatman2]

I don't mean to be funny but why are you taking structural advice from brickies?

If you want a successful build then get the rationale for either approach from someone that knows what they're talking about. No doubt a brickie will have built many variations but that will be about it.

[roofer]

ShredderXLE said:

I thought the mesh was there to remove the need for movement joints and control cracking - not provide stability which is what the piers are doing. Although exempt from the regs due to the small size, approved document A does have a guide to postion and sizing of piers to resist wind loads in small single storey buildings such as garages.

What he said.

[uk66fastback]

Interested in what you're paying for the brickwork and roof etc (rough guide would suffice) a mate is looking at having one built ...

[worsy]

Just picking up on the carpet the walls suggestion. I bought a few packs of polystyrene insulation from B and Q and then no nails them to the wall. Provides a cost effective protection and carpet can be a little heavier.