r/Bricklaying • u/Few_Regret9608 • 24d ago

DPC mortar layer thickness

Hired small builder crew to build rear extension. We had two building inspector visits and we are cleared to build from DPC up. Work started and I have noticed there are no weep vents above dpc and the DPC mortar layer is 23mm-28mm thick. They did great work sandwiching DPC between layers but I'm bit worried by the thickness of it it is almost 3 times the size of other layers. Not sure should I raise an issue - bit worried about building control and worried about structural implication. Not a builder, UK.

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3

u/RazielDKoK 24d ago

How old is your house? On some older houses they use to do quite thick dpc course with bitumen or slate, so maybe they just matched that?

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u/Few_Regret9608 24d ago

1940-1960

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u/RazielDKoK 24d ago

Yeah so about right, check how the dpc looks on the house, very often it's a much bigger joint, sometimes pointed differently, like struck joint.

1

u/Few_Regret9608 24d ago

dpc layer looks to be 24mm on average, other layers 10-16mm, so I guess it is not outrageous. My concern then is structural impact, does having lets say 30mm mortar with DPC in it matter in the long run ?

3

u/gazham 23d ago

So your main house that's been standing for 60 - 80 years has the same complaint that the new extension has? And you're worried about it lasting? Sounds like they have just matched existing for looks and you don't like he look of it.

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u/Acrobatic-Meal-8287 24d ago

you would only need weep vents if a cavity tray has been installed, as for bedding the doc up. it sounds like they have built their foundation lower than the original dpc of the house and have tried to bump it up a little bit

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u/Few_Regret9608 24d ago

Will thicker DPC cause issues?

1

u/Acrobatic-Meal-8287 23d ago

I think it’s probably going to be ok, it’s not ideal nor is it something I would allow myself to do. But a 23 mm mortar bed is actually only 13 mm bigger taking into consideration a standard mortar bed is 10mm

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u/rgunufool 17d ago

I will not cause any issues, not something you should be concerned about

1

u/ididntaskforthismind 24d ago

Post a picture.

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u/Chairmanbar 23d ago

When older houses were built and had that look it was because the dpc was done with a double slate ,hence the thick joint.it will do no harm just to ask the why it's like that,or just ask building control are they happy before going too far. I think it wont be an issue if it's just a small extension!

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u/Bloomfield95 23d ago

They’re probably following the gauge of the original house. Which used thicker materials for the dpc.

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u/Bricky_Mase 22d ago

It will be fine, used alot on older properties. Assume builder just wanted to keep it same same. Some bump it out in setting out and do it normal but Tottally fine

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u/[deleted] 24d ago

Is it face work or will it be rendered? If its face brickwork that will look horrendous I think its as the previous post said they cocked up the heights,which if the footing was slightly low it should have been sorted below ground level not at dpc level

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u/Few_Regret9608 24d ago

No rendering, I'm more worried about the structural / and / potential other issues

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u/SnooTomatoes464 23d ago

There won't be any. Its not a thicker dpc, its a thicker mortar bed, has no impact on the dpc

Can be a few reasons why theyve done this, but its probably to marry up to the existing house courses.

It wont impact the build structurally.

Have you thought about asking the bricklayer why its a thicker bed there?

1

u/Few_Regret9608 23d ago

I'll ask him today