Stone plinth timber cladding arrangment

[fergoose]

Hi 

We are begining our extension to a grade 2 listed building and on the front eleveation the conservation officer has request a stone (to match existing) plinth approx 300mm high with vertical board on board cladding above. We want the cladding to be roughley in line with the plinth and finish dowen on to it I was thinking the membrane. Does anyone see any issues with the attached section?  on all other sides the plinth is not rquired so we will render the xps plinth insulaton. Do we need the void behind the stone? or can the stone be up against the plinth insulation? like an insulated cavity? (this would be my prefered way)      

 

We are keen not to have the stone forward of cladding as it will have 180 degree outward opening door shutters that we dont want to snag on the stone. 

 

although not drawn, there will be periscope ventilltion through to the stone plinth for block and beam and rodent/insect  mesh installed behind cladding.

 

Thanks for any comments.

 

wall sections.pdf

 

[Mr Punter]

I am a bit uncomfortable in having flammable ventilated rainscreen cladding with plastic insulation and membrane.  Hold a flame to each of these and see if they burn.  I once had a house catch fire when a plumber was joining some copper pipe for the gas and the flame from the blowtorch set the membrane alight.  Luckily we managed to get access to the top and got a hosepipe in there before the fire took hold of the building.

[fergoose]

Thanks I may use the SOLITEX FRONTA QUATTRO FB membrane if we are concerned about fire. The main insulation is woodfibre. Given you have to vent timber cladding  what are the other options, My OP  was realky about the detail at the plinth with the stone. 

 

 

[Mr Punter]

Sorry, I missed the woodfibre insulation detail but you mentioned XPS insulation.  Is it OK for use woodfibre below ground as per your detail?  Best have the manufacturer and BBA certify this as you won't be taking it out later!  As for the cavity below ground, again look at the BBA certificate and the manufacturer's instructions and warranty.

 

Apparently Siberian Larch is in short supply and the local stuff is nothing like as durable.

 

The breather membrane over the top stone will need to be supported.  Are you having a flashing from the insulation to the stone plinth to prevent rainwater running into the cavity?

 

It is worth making sure the door threshold and reveal details are nailed down.