Extension width/length not divisible by exact brick size

[JimExtension]

Hi,
Our extension width and length is not divisible by an exact number of bricks (taking into account a standard mortar width of 10mm). This is for an extension with planning permission - not permitted development.

What might be the best approach?
- create the walls slightly under the planned size (I think it would be -7cm from plan on the width for example).
- go a bit over - might be 4cm over for this wall.
- adjust the mortar width a little bit bigger/smaller across the wall to get to the correct width/length.

What margin of errors are acceptable to local councils for width/length in these cases?

Thank you

 

[pcaouolte]

4cm? As in 1 and a half inches? Who is going to measure it?

In my experience most builders don't work within margins that tight. If you are lucky they might have a glance at the plans before they slap down some bricks somewhere close to where they were meant to be.

 

[Notch7]

Just make the extension to the drawing.

put in a broken bond to suit to suit the overall dimension. In general most elevations are broken up by openings so it’s only the 2 courses below DPC that are full runs

I wouldn’t try stretching or shrinking the perps

obviously if you have a door opening near a corner or a narrow panel between openings if they can be made to a brick multiples like 450, 675 etc it helps.

 

[noseall]

What might be the best approach?

Hire a brickie that knows how to pinch a few mill of gain a few mill.

 

[23vc]

Hire a brickie that knows how to pinch a few mill of gain a few mill.

This. You just lay the first course out and adjust as needed to still fit, and the perp joints still look about 10mm. (Unless it’s an absolutely tiny wall)

 

[JBR]

Adding one mm (or taking away one mm) to or from each width of mortar will result in a far greater (or lesser) difference in the whole length. In fact, you could get it exactly right by measuring the distance to the eventual end as you move along and making the required minor changes!

 

[^woody^]

Build to the dimensions. Many a brickie has thought he knew best or wanted the easy life and had jigged buildings and openings around, and come unstuck later

All face brickwork should be set out dry at DPC level in the bricks that will be used for the facework, and that includes setting out all the openings too.

You often find that the bricks below DPC are different size to the ones above, joints are not 10mm, bricks are not 215mm and openings are not the same as frame sizes. So you work to overall sizes and make things fit.

I remember the times when the clerk of works wanted 4 bricks exactly every 900mm and the Architects wanted every joint exactly 10mm. And we just wanted to go home.

 

[George_engineer]

Plan dimensions generally have a 25mm tolerance, especially if there isn't a professional survey. Existing buildings might have been built at a an angle and so on. I'd generally not worry too much about the plan dimensions but pay attention to where it is supposed to line up with the existing building.

If you do need to fit to a non-brick dimension then a closer might be a better bet than altering perp widths.

 

[^woody^]

a closer might be a better

Noooooooooo.

There are rules you know.

 

[stuart45]

You don't use closers in stretcher bond. Normally better to tighten up joints rather than open them up. You can often reverse the bond, and use a 3/4 in the best spot as well.

 

[George_engineer]

You don't use closers in stretcher bond. Normally better to tighten up joints rather than open them up. You can often reverse the bond, and use a 3/4 in the best spot as well.

I meant a bat.

To me a closer just meant a cut brick, not specifically longitudinal cut. It's only when you go into Queen/King etc does it get precise.

 

[Notch7]

Hire a brickie that knows how to pinch a few mill of gain a few mill.

surely they can all do that?

 

[noseall]

surely they can all do that?

Some like to gain or lose quickly, resulting in a kind of accordion type of bricklaying whereby the brickie loses too quickly then has to gain again (or vice versa).
The trick is to set out - fiddle with that first course - then try and keep your perp's in line (vertically). Nowt better than looking down from the top lift and seeing in line perps.

 

[stuart45]

On some higher class jobs you had to use pencil marks every 4th brick to keep the cross joints perpendicular.

 

[stuart45]

I meant a bat.

To me a closer just meant a cut brick, not specifically longitudinal cut. It's only when you go into Queen/King etc does it get precise.

A half bat is generally the smallest you can use in Stretcher bond. There are some exceptions such as when corbelling.