DPC width

[sm_jamieson]

Need to purchase DPC for cavity wall with 102mm leaves (ie brick/ block). Notice screwfix sell widths of 100mm and 112.5mm. Which should I use ? And why ? Thanks, Simon.

[Unbeliever]

Simon,

Forgive me for being blunt, but the mind boggles at this sort of question.

Ask yourself the question - do you want the DPC to be seen sticking out past the brickwork/blockwork after you have installed it - or not?

If you don't, then fit the 100mm one. If you do, then fit the112mm one, especially if you then want the trouble of cutting the overhang off after.

As for the 112mm DPC, think imperial and the old 41/2" wide brick rather than the narrower metric (4" wide) brick and then make your choice.

Unbeliever.

(Or should that be Disbeliever)?

[sm_jamieson]

Stating the obvious is the mark of a genius, so I've heard. I should think the same applies to asking ;-)

Upon thinking about this myself, I remember that its recommended that DPC should extend 5mm beyond the wall (can't find it in Part C though). Do you think its a coincidence that two standard dims are

90mm blocks and 102.5mm bricks, and the DPC sizes are 100mm and 112.5mm, i.e. exactly 10mm more, allowing a 5mm overlay on both sides ? If the DPC was slightly smaller (using 100mm on 102.5mm bricks) then the leaf then it could be bridged. Would the BCO fuss about this ? Simon.

[Cerberus .]

I would have thought that using 100mm DPC on a 102mm thick wall would defeat the object & leave it wide open to rising damp.

Don