Limestone block wall too expensive?

[theprinceofdarkness]

I need to build a lean to workshop and summerhouse on the side of my house. The design is 3m wide, 5m long (workshop) plus an extra 3m for the summer house. There will be 4m along the side of the house with 4m sticking into the back garden, so the workshop entrance will be on the extra 1m of the workshop giving a 3m frontage for the summer house, which will have a set back front wall with a veranda, but covered by the same roof.
I would build it from wood but I live in a National Park. These people are very snoty about planning consent, they want every thing built from limestone blocks. My main question is can you build a single skin limestone wall with a timber frame inner skin with wall ties between the two? The standard construction for a house round here would be limestone outer leaf with celcon blocks for the inner skin, with a 2" cavity and 4" of insulation. Ideally I would build the lot out of wood for cheapness but insulate it properly. I could shave the price by using medium density concrete blocks. As a workshop for model engineering , I do not want a dense inner skin construction, else when I go into to it in the winter and turn the electrical heater on, the place would take 4 hours to get warm, just in time for me to go back to the house for my tea!
Frank

 

[noseall]

My main question is can you build a single skin limestone wall with a timber frame inner skin with wall ties between the two? Frank

Yes.

You would need to design it properly though as the inner (timber skin will be taking the weight of the roof.

As with any timber frame building, you will need to build the timber frame first along with all the plywood sheathing, VCL, breather membrane etc. I often wonder whether this is any cheaper than a internal skin of aerated blocks...?