Plinth brick cavity construction

[Peter M]

I am just about to start our exterior facing brick and blockwork upto DPC which will involve a skin of 105mm facing brick and backed up with a 50mm block to give a 155mm (ish) outer skin which will eventually be set in by 50mm once the plinth brick has been laid.

 

My question is, would I be better placed to use a 50mm dense concrete or a lightweight aircrete block, the building regs document does not specify which to use and as there will be an inner skin of 100mm thermalite block together with 100mm cavity insulation strength over cost may be the major consideration, there are probably pros and cons apart from the cost angle so I'd be happy and interested to hear what you guy's thoughts are.

 

Cheers

[PeterW]

You may struggle to find a 50mm block as there are very few suppliers who will do them these days - any reason you have to have a 155mm outer wall ..??

[bassanclan]

No idea what those 50mm blocks are there for?

I would ditch the 50mm blocks

Make the cavity a little wider and just use standard 100 (102/105mm??) bricks.

[Peter M]

13 hours ago, PeterW said:

You may struggle to find a 50mm block as there are very few suppliers who will do them these days - any reason you have to have a 155mm outer wall ..??

The outer wall thickness of 155mm is to provide suitable support for the plinth brick which when laid will then provide at least 105mm for the courses of brickwork that will form the outer skin of the standard cavity construction eg. 105/100/100

I hope that I have explained clearly

[Declan52]

You can use a brick cut in half if you can't get any of the 50mm blocks. If you can get the blocks just standard blocks will do.

[Peter M]

I have found a couple of suppliers that carry both concrete and lightweight 50mm blocks but I wasn't too sure if I should go for the strength of concrete over the slightly higher cost of lightweight block option really.

[PeterW]

Sorry so this is just to support the plinth .,? How high are you building it ..? I would sacrifice 15-20mm of the cavity and just go brick on edge if it's only a few courses from DPC. 

[Peter M]

43 minutes ago, PeterW said:

Sorry so this is just to support the plinth .,? How high are you building it ..? I would sacrifice 15-20mm of the cavity and just go brick on edge if it's only a few courses from DPC. 

No it's more like a metre from concrete strip foundation to underside of windowsills and then mostly cladding above the plinth

[Brickie]

I'd go for concrete myself,especially if cheaper!

Point to remember with plinths if there's any masonry carrying on above-the bond needs to be set out for the brickwork when it steps in,which may mean 3/4's at the corners. 

Edited August 9, 2017 by Brickie

[PeterW]

What's the cladding detail ..?? Is this onto an external frame stood on the plinth or cladding on blockwork..?

 

Have you got a section drawing ..?

[Peter M]

3 hours ago, Brickie said:

I'd go for concrete myself,especially if cheaper!

Point to remember with plinths if there's any masonry carrying on above-the bond needs to be set out for the brickwork when it steps in,which may mean 3/4's at the corners. 

As an ex bricklayer I'm aware of ensuring that the bonding is set out correctly and some thought has to go into the bonding it's the kind of detail that spoil the overall effect if not properly thought out. Appreciate your comments tho

[Peter M]

3 hours ago, PeterW said:

What's the cladding detail ..?? Is this onto an external frame stood on the plinth or cladding on blockwork..?

 

Have you got a section drawing ..?

Sadly our architect didn't give any clear details about the plinth and cladding as it was only shown as an option in the building regs document we can of course go back to him but as we will be applying for a minimal change on window and door positions we'll ensure that the plinth is also covered at the same time but for now up to DPC detail is not so important but suffice to say that there will be a traditional block and block cavity where cladding is involved