A builder's opinion please

atprice

Hi all. I've got a 1930s house in Manchester that's built with the really solid red stock bricks, the kind that break hefty masonry bits.

So I've noticed that the bottom row of bricks have started to deteriorate to the point where some of them will need replacing. At first I thought the damp course had been bridged and they were acting as a soakaway. However, it looks like the previous owner has actually dug down once course of bricks so the ground level in relation to the damp course is lower than originally intended. Although logic dictates that this is a good thing, could this actually be causing the problem? Any feedback is very gratefully received!

Doozergirl

No, digging away won't cause a problem, but the problem could have already started before they dug down and that was the remedy? Where is the damp course in relation to the blown bricks?

Do you have pictures?

atprice

I don't have pics but I'll try and put some on later. It's hard to see where the original damp proofing was, but I had the damp course redone when I moved in a few months ago so I'm hoping that if I replace the bricks it won't happen again.

Could it be that the bricks are deteriorating because they've been exposed? A stupid question because a brick's a brick, but the others seem fine.

Doozergirl

No. Bricks are supposed to be exposed. Engineering bricks should be used below the damp course as they don't soak up water which is present below DPC and are resistant to frosts.

If you had water get into fractures in the wrong bricks, then in a cold winter the water will expands as it freezes and blow the bricks.

I'm making wild assumptions here without pics.

atprice

Would they have used engineering bricks back in the 30s? Should I be making sure that any replacements are engineering bricks?

Sorry for asking so many questions but I'm finding this really useful

tony6403

You'd think that engineering bricks, which have high strength and low water absorption , would resist frost better than bricks with lower specifications.
But they don't.
There is no real relationship between strength or water absorption and frost resistance.
Here is an extract from the Brick Development Associaton's take on the matter
"More importantly there are many bricks of only modest strength (7-20N/mmî) and high water absorption (20%-30%), which have excellent resistance to damage by frost action. "