Beware Flemish bond vs brick size

[MortarThePoint]

Well this is more of a therapy session post or cautionary tale for anyone else.

 

I spent a long time bonding the house out at the design stage, including the periscope vent positions etc and it was all based on 215 mm stretcher and 102.5 mm header. The packs have 215 and 102 marked on them so fine there, checked. Reality is the bricks are all 210mm and many less, very few more and don't think I have come across a 215 mm one yet. Headers more like 98mm. They are stated as size tolerance T1, and that allows a range of 209 - 221 mm. Some are a tad under the 209 mm, but certainly the average isn't 215 mm. I'd say the average is likely 210 mm. To keep as bonded out in theory would make for 15 mm perps which would look bad. The brickies are bonding out now and there are lots of double header and double stretchers being deployed to fix this discrepancy.

 

This has caught out the Architect as well as he set loads of dimensions based on theoretically working for bond. Thank goodness I haven't ordered the windows yet.

 

Learning: check your bricks for real size distribution before finalising dimensions.

[Mr Punter]

This can also be a real pain with timber frame where the openings are already there.  Bricks and blocks can vary considerably in size.

[the_r_sole]

what bricks have you got? that's some tolerence!

[MortarThePoint]

43 minutes ago, the_r_sole said:

what bricks have you got? that's some tolerence!

 

Wienerberger (Terca) Pastorale Multi. It must be deliberate to save some pennies on materials. I was nervous that too many decisions get made on the basis of a pack or two so we sampled across a number of packs.

[PeterW]

That is the shrinkage from firing and is water content dependent. Used to be a useful document about it on the Ibstock website. 
 

2-3mm variance is very good - last job we used reclaim imperials on, they varied from 207-230mm, 70-80mm deep and 95-115mm width ..! And they weighed over 2kg each !!