We have permission to extend a stone-built bungalow - essentially one large room with a small brick lean-to. The extension will essentially be one new room housing kitchen, dining room/living space, plus two small bedrooms above the existing stone room, with dormers, plus a small porch. We're planning on wood cladding for the extension, exposed stone/lime pointing for the existing part. Heat would come from a woodburner.

We're in a deep valley on Dartmoor and that being the case our site is subject to a lot of atmospheric damp - for instance, from September on, even when the sun is shining (it does happen once in a while), the dew doesn't evaporate from our stone path. I'm wondering if this ought to influence our choice of building material. Quotes for pre-made timber frames are attractive, SIPs slightly less so but there's the convenience. Local builders would want to use blocks or stone. A SIPs person said he wasn't all that keen on using SIPs for walls in damp locations. Unfortunately, times being what they are, the build is extremely budget-sensitive, ie cheap as chips is what we're after, but we don't want to sacrifice quality or eco considerations. We're tempted to go with a SIPs roof, but it's the walls that are the dilemma. Any input would be gratefully received!

SIPs and timber frame might be difficult to integrate onto the stone building. If it is two storey, you would need to consider differential movement between the timber frame or SIP and the existing stone structure.

you could go for concrete blocks with EWI, battens and then the timber cladding.

What do the planners want on the outside? Are they ok with the wood cladding?

Have a gd read of http://www.greenbuildingforum.co.uk/forum114/comments.php?DiscussionID=6890&page=6#Item_16 for cheap-as-chips all-timber (on site) super insulated airtight construction. I'd have thought that finally knocks

Posted By: tonystone cladding wide insulated cavity block inner must be cheapest

on the head, esp when you consider the massive extra excavation extent and found walls (if not trenchfill) to support a heavy outer skin.

Try http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=6890&page=6#Item_16%20for%20cheap-as-chips%20all-timber