DPC and brick slippage ... stupid question

[rideforever]

Hi, I am not a builder just curious. I often saw that the foundations of a house have a DPC membrane that is put above the foundation courses and the above ground structure.
My questions is ... don't the bricks above slip off the DPC? Are the bricks above tied to the bricks below or is it safe to mortal the DPC to the lower course and mortar the upper course to the DPC?
Is there something I am missing.
Sorry stupid question I'm sure.

 

[jeds]

It's not unknown for brick courses to slip on the dpc, but when that happens there's something seriously wrong with the design or the build. Some lateral force; clay heave or expanding timber frames could do it. Plastic dpc has an embossed grid on the surface to help control any lateral movement.

 

[rideforever]

It's not unknown for brick courses to slip on the dpc, but when that happens there's something seriously wrong with the design or the build. Some lateral force; clay heave or expanding timber frames could do it. Plastic dpc has an embossed grid on the surface to help control any lateral movement.

Thanks ... but masonry to plastic is not a good bond, it's not like plastic to plastic or mortar to mortar.
Is there no technique to interlock the DPC through alternate bricks or courses so that there is a continuous concrete bond interwoven in it?
Couldn't you just heave on the brick structure above the DPC and slide it off?

 

[Charlie George]

The 100+ tonnes of weight on top will stop it slipping,and apart from mortar nothing connects the two,it won't move unless theres a serious problem.

 

[mikeey84]

Couldn't you just heave on the brick structure above the DPC and slide it off?

One or 2 courses of a short wall? Maybe.

A full house? Overcoming the friction and inertia generated by 100s of tonnes of bricks would be pretty tricky

 

[rideforever]

The 100+ tonnes of weight on top will stop it slipping,and apart from mortar nothing connects the two,it won't move unless theres a serious problem.

Yes 100 tonnes vertical, but horizontally the upper structure has little resistance, like with Earthquakes.
I am not a builder but I am surprised there isn't a different solution, like using special lapping bricks over the DPC at intervals (using the cavity in cavity walls) with the DPC wrapping over the lapping brick. This would provide horizontal stability without breaching the DPC.

Another simple way is for the DPC to run not horizontally but go up and down over the bricks creating "teeth" .. so it's using 2 courses rather than 1. If this is done on all the exterior walls then there is horizontal locking.
As an outsider it seems strange that this isn't done, but sure houses don't fall over frequently.

 

[jeds]

But millions of houses are built without special lapping bricks. Masonry isn't expected to 'bond' with the dpc to the extent of holding it together. In fact brick walling is hugely strong in compression but actually very weak in tension. There's a saying; mortar doesn't hold the bricks together - it holds them apart.

 

[^woody^]

Check out Newton's first law of planetary motion.

And friction

 

[stuart45]

Check out Newton's first law of planetary motion.

And friction

Can't find any mention of a DPC in it.

 

[^woody^]

Can't find any mention of a DPC in it.

The damn builders are always ripping that page out

Here you go ..

 

[mikeey84]

Newton's cradle demonstrates his 3rd law, not his first

 

[cdbe]

Happened to me, I only leant on the wall.

 

[charliegolf]

Planetary motion? Keppler, no?

 

[^woody^]

Newton's cradle demonstrates his 3rd law, not his first

It demonstrates all three laws.

 

[mikeey84]

It demonstrates all three laws.

Well, as with (almost) all physical objects, it obeys all 3 laws, it primarily depicts the conservation of momentum. Whilst it does demonstrate the other 2, it is a particularly poor demonstration of the 2nd