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epsilonGreedy

Any problem at an external door if the outer wall DPC is 75mm below the inner?

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The planning office is making noises of discontent about too many blue engineering bricks possibly showing above ground level. The average would be 5 courses because the site slopes and a minor flash flood risk necessitates DPC should be 150mm higher i.e. 4 bricks rather than 2 above ground level.

 

I could reduce the number of exterior blue courses above ground by lowering the DPC by one brick which would be one brick below FFL.

 

Is a door step threshold complicated to finish when the external cavity wall DPC is one brick lower than FFL and the floor membrane that laps up to the DPC running across the top of the first inner block?

 

More Info:

  • I have a standard block and beam suspended floor with 100mm thick blocks.
  • Above the floor blocks I will have 150mm of insulation plus 65mm of screed with a few mm spare for a tiled floor finish.

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If the volume of blues is an issue can you not just start with the superstructure facing bricks a couple of courses lower.?
I’d leave the DPC where it should be. 

Edited by Brickie
Nesquik
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49 minutes ago, Brickie said:

If the volume of blues is an issue can you not just start with the superstructure facing bricks a couple of courses lower.?
I’d leave the DPC where it should be. 

 

 

Yes I am trying to reduce the total m2 of blues showing above ground.

 

The above DPC bricks are F2 rated so good for below DPC though I suspect their hand moulded origins means they are at the lower end of an F2 rating.

 

A few months back I suggested one course of regular facing bricks below DPC and someone more experienced did not approve.

 

I might till consider this however it causes an additional mortar colouring challenge. I have settled on a 50-white/50-grey mortar mix at 1 to 3 sand for the blues because I do not like a pure white mortar showing between the blues. The above DPC 5 to 1 sand/cement mix colour is now settled at 5 parts white cement to 1 part grey.

 

A course of buff bricks below DPC will require a mortar that still looks sandy at a stronger 3 to 1 mix. I suppose we are only talking about the perps mortar colour in this below DPC course.

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Our inspiration is this property in the Yorkhandmade brochure though in our case there is no parapet formed in the blues, our FFL is about 250mm higher and at most the top blue course will be level with the door step.

 

This post discusses the option for the top blue course sitting under the doorstep plinth instead.

 

https://www.yorkhandmade.co.uk/kilburn-handmade-bricks

 

Kilburn_redwood1.jpg

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On 29/01/2020 at 11:46, Brickie said:

If the volume of blues is an issue can you not just start with the superstructure facing bricks a couple of courses lower.?
I’d leave the DPC where it should be. 

 

 

My Building Control Inspector has confirmed your advice. He recommend leaving DPC where it is i.e. 150mm higher than standard NHBC standards and having two courses of regular facing bricks (F2s) below DPC, this will leave 2 rather 4 blues exposed and hence of less interest to the conversation officer.

 

I mixed up a test mortar batch last night at a 3 to1 sand/mortar ratio but with the mortar component the same 5 to 1 white/grey cement ratio and it produced the same nice sandy/caramel colour once dry.

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