Mortar Bed thickness - too thick?

[James Davis]

Hi all,

Extension is progressing. I've noticed at the tip of the concrete blocks where the engineering bricks being that there is an area where the mortar bed is really thick. Looks about an inch thick, presumably to make up for some unevenness in the blocks below. How thick is too thick in terms of structural soundness?

 

[jj4091]

It's fine they were probably levelling up from the foundations

 

[23vc]

As said, nowt wrong with the bottom bed really but second one ups about half the thickness of the top one so possibly keep an eye on things.
Looks like you’re getting weather struck type pointing, assume you’re expecting that…

 

[James Davis]

As said, nowt wrong with the bottom bed really but second one ups about half the thickness of the top one so possibly keep an eye on things.
Looks like you’re getting weather struck type pointing, assume you’re expecting that…

Yes, like the existing house. Is there a problem with that type?

 

[23vc]

Yes, like the existing house. Is there a problem with that type?

No, not at all. All good

 

[Ivor Windybottom]

Looks great, send him my way when it's done.

 

[^woody^]

Is this the DPC?

 

[James Davis]

Is this the DPC?

No, between bottom of engineering brick and concrete block.

 

[^woody^]

Ok. Yes, either for leveling, or if out of leveling you'll get another one further up.

 

[James Davis]

So how thick can a mortar bed be before it is too thick for structural purposes? I mean, what's he point of bricks if you can just have a giant slabs of mortar?

 

[George_engineer]

So how thick can a mortar bed be before it is too thick for structural purposes? I mean, what's he point of bricks if you can just have a giant slabs of mortar?

Up to around 25mm would be alright although it'd benefit from some sharp sand in the mix to give it more strength. The larger the bed joint the less confinement is provided to the mortar to keep it whole. Brick laying mortar is a brittle material and is quite liable to crack.

A masonry wall gets its strength from the bricks, which is the ability to transfer vertical load and the mass of the bricks themselves to resist lateral loads. Although a masonry wall is a combination of two brittle materials (bricks and mortar), the mortar gives a masonry wall flexibility to carry more load by allowing small cracks and micro-deformations, transferring stresses progressively through the wall, rather than just cracking and falling to pieces. Mortar also weatherproofs the wall, allows the bricks to be lined up and transfers the vertical load from brick to the next brick. But it isn't really an adhesive - in normal masonry design you pretty much ignore the 'stickiness' of mortar, theoretically if you could keep sand in place then a masonry wall would essentially be just as stable.

 

[Ivor Windybottom]

So how thick can a mortar bed be before it is too thick for structural purposes? I mean, what's he point of bricks if you can just have a giant slabs of mortar?

Concrete strctures essentially are exactly that. They don't usually fall down.

 

[^woody^]

It's the old question ...

"Is mortar intended to keep the bricks together or apart?"

 

[Nige F]

An old brickie told me to keep them apart. He called big joints Christmas joints cuz you always have a big joint at Christmas.

 

[Deluks]

It's the old question ...

"Is mortar intended to keep the bricks together or apart?"

Both.

Apart together, it's like a situationship.